Oral-History:Yukikazu Iwasa

About Yukikazu Iwasa

Yukikazu Iwasa was born in Kyoto, Japan on February 15, 1938. After completing primary and secondary education in Japan, he attended Westminster College in Utah for a year before transferring to the Massachusetts Institute of Technology. In 1962 he earned a B.S. and M.S. in Mechanical Engineering, and a M.S. in Electrical Engineering, followed by a Ph.D. in Electrical Engineering in 1967. Starting In 1964, Iwasa joined the the staff of MIT’s Francis Bitter National Magnet Laboratory (FBNML), later the Francis Bitter Magnet Laboratory.He has been there ever since. In 1964-1966 and 1967-1982 he was on the research staff, 1982-1996 he was Associate Head of the Magnet Technology Division, and in 1996 he became head of the Magnet Technology Division. In addition to this, he was a graduate research assistant in the MIT Electrical Engineering department from 1966-1967 and became a research professor at MIT in the 1980s, teaching courses in mechanical engineering and superconductivity. His research interests focus on low- and high-temperature superconducting magnet technology, and cryogenic engineering, culminating in the publication of several journal articles and a first edition textbook, Case Studies in Superconducting Magnets (1994); a second edition followed years later.

In this interview, Iwasa outlines his accomplishments in the field of superconducting magnets during his time at the FBNML, especially his work on adiabatic magnets, MgB2 applications for MRIs, and fusion magnets. He discusses the social and professional difficulties and challenges faced during and after the Second World War as a Japanese citizen. Additionally, he reflects on his contributions to the development of superconducting magnets, and on the evolution of the field over the course of his career.

About the Interview

YUKIKAZU IWASA: An Interview Conducted by Sheldon Hochheiser, IEEE History Center, 14 August 2014.

Interview #658 for the IEEE History Center, The Institute of Electrical and Electronics Engineers Inc.

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Yukikazu Iwasa, an oral history conducted in 2014 by Sheldon Hochheiser, IEEE History Center, Piscataway, NJ, USA.

Interview

INTERVIEWEE: Yukikazu Iwasa
INTERVIEWER: Sheldon Hochheiser
DATE: 14 August 2014
PLACE: Charlotte, North Carolina

Youth, Family, and Education in Japan

Hochheiser:

This is Sheldon Hochheiser of The IEEE History Center. It is the 14th of August, 2014. I'm here at the ASE Conference in Charlotte, North Carolina with Professor Yukikazu Iwasa of MIT.

Iwasa:

Yukikazu is my full first name, but you can call me Yuki.

Hochheiser:

If we can start with a little background.

Iwasa:

Yes.

Hochheiser:

Where were you born and raised?

Iwasa:

I was born in Kyoto, Japan. February 15, 1938.

Hochheiser:

What did your parents do?

Iwasa:

Before the war in Japan, the first-born son inherited the entire business. And he [my father] was a third son so in Kyoto in those days, he was given a few rental houses to supplement his salary income. After he graduated from a university with a law degree, he went to work for a private railway company, headquartered in Osaka. Then as the war was approaching, I don't know about in the U.S., but, I think I can say now, because he's passed away and the war was a long time ago, many draft-eligible young Japanese men, including my father, didn't want to serve.

Hochheiser:

Yes.

Iwasa:

He always wanted to go abroad. And he did travelling in his school years. Mostly China, Korea, and within Japan. And he applied for a management position at the Miyako Hotel. I think it's a five star hotel now and it was the best hotel in Kyoto. And he was accepted because he wanted to go abroad before the army got him. So he went to Indonesia, I think, in 1943. I know he was away about two years as the General Manager at a beautiful hotel in Bandung mostly for Japanese, high-ranking military and VIPs visiting Indonesia. And he sent us photos of a really nice house that we were all going to move in after Japan won the war. And we really thought Japan was going to win the war. I still remember my mother asking him to make sure he buys a Steinway grand piano. That's when I first heard the name Steinway, and when I first bought a house that we still live outside Boston in 1969, I bought a Steinway, even though by then I hardly played piano. Somehow the name Steinway had stuck in my head. But of course Japan lost the war in the summer of 1945, officially ended tomorrow, August 15th.

Hochheiser:

Right.

Iwasa:

I think he came back either that fall or the following spring. He was one of the earliest expatriates to return. And then he went back to the railway company where he had once worked. But he was kind of an entrepreneu,r so he established a small company. Investing, what do you call that? You put money into various companies hoping it will grow, a venture capitalist. As an investor he made a major mistake not choosing a company in Tokyo that was trying to develop electric sockets for vacuum tubes. That company was NEC, Nippon Electric Corporation. He wanted to but he had a very good friend in Tokyo who also wanted his investment for the same product development. So he chose him over NEC. So that was a big mistake too. But then he eventually invested into this catering company in Kyoto, which also had a chain of restaurants and this investment turned out to be quite successful. So in a way he was a businessman. He didn't know about the catering or restaurant business but he somehow chose right people to run it.

Hochheiser:

Were you interested in science and technical things as a youth?

Iwasa:

Not really. Not at all. In fact, the war ended, when I was seven. Another interesting thing is that Iwasa family was from Kyoto. But my parents as early as in 1938 thought war would be coming. And they were absolutely sure Kyoto would be bombed. So he moved us into a small very upscale town, midway between Osaka and Kyoto, which his railroad company had just finished developing. In Japan for most people the favorite location is near a railway station because at that time there were no private cars. So we moved to this upscale residential place that his railroad company had developed. And therefore, we didn't have any bombing experience. And I spent most of the time in the river looking for fish and things like that and collecting insects. That kind of thing actually lasted through my senior high school. So I never had any interest in science. The schools I attended were Doshisha Junior High School and Senior High School. I don't know if there's any in the US but in Japan, many private universities have their senior high schools, junior high schools, elementary schools, and even kindergartens. And if you get into the kindergarten, then you go to its elementary school without any exams. Then its junior high school, then the senior high school, and then, the university. So you escape a series of the entrance exam “hells” common in Japan, except at the very beginning. I went to a public elementary school within a walking distance because I began the elementary school during the war.

Hochheiser:

Right.

Iwasa:

And when I got into Doshisha Junior High School in 1950 I had to commute every day by train to Kyoto. And then by bus. So it took almost one hour from home to the school. So my parents decided to return to Kyoto and in the summer of 1950 they bought a really nice Japanese house near my school, about fifteen minute walk. In those days, Japan--I usually tell my Japanese students especially young Japanese that Japan at that time was like North Korea now. You know, it was very poor. Roads were not paved. But my father always liked new stuff. So he bought a car and all that kind of things. But he didn't want to drive. So we had a chauffeur, the very first one living in our house. And so we used to visit many places with our car driven by our chauffeur. Our house was essentially a Japanese style house. But my mother liked cooking. So they renovated its original Japanese style kitchen, which was very inconvenient but my father liked for its looks, probably he never had to cook and I don’t remember seeing him cook, into the western style and converted one Japanese style room into a dining room, with a dining table set and all. But the rest, except the three Japanese style toilets, which were converted to the Western style, was kept in the Japanese style. The house had two outhouses, liquid only and solid, for our maids, chauffeur, and a day-time handy man. We had a really nice Japanese garden, a teahouse and so forth. And my parents knew the mayor of Kyoto quite well. Am I changing the subject or shall I continue?

Hochheiser:

No that's fine.

Iwasa:

I was going to tell you how I got to MIT.

Hochheiser:

And you are. Keep going.

Iwasa:

Well number one, they had decided I shouldn’t go to Doshisha University like rest of my classmates because if I did, I wouldn’t study. You know, in most Japanese colleges, unless you are really dedicated, you don't study. In a way it was a period of rest and relaxation after the exam hells. So they decided that I had choices, either I would go to University of Kyoto, which was, and still is very difficult to get in and where my parents thought I would study or go abroad. Eventually, they decided I should go to the US. Actually, my mother majored in English in college and she always wanted to come here to study. But she was the first-born daughter and her parents didn't want her to leave Kyoto.

I still remember during the war, when we all thought Tokyo, Osaka, and Kyoto were major targets. I heard after the war that for the B29 the milestone was Mount Fuji. And if they wanted to bomb Yokohama and Tokyo, they just turned right. And if they wanted to bomb Osaka or Kobe or Nagoya they turned left. So we used to see quite often many B29s high above our small town flying towards Osaka. And of course, if the B29s were flying above, everybody had to assume you might be bombed. My father was still in Indonesia, and my mother, my brother and I, three of us, were just hoping nothing would happen. In one of these frightening moments, I clearly remember my mother telling us, "Well after the war, you’ll go to America to study." Even at a small age (I was six), by late 1944 and till the war ended in August 15, 1945 I suspected that she began to realize Japan was going to lose. And she was a very interesting woman in a way. She never wore this special Japanese style cloth (“mompe”) that every woman wore during the war. She always wore a skirt and high heels or a kimono. And her younger sister's husband was a prominent businessman sent to China from his company and she accompanied him to China. They stayed in Shanghai before and during the war. They moved to Dalian during the late phase of the war because her husband was drafted into the Japanese imperial army. My mother liked everything made in USA. She used to say that the only things good that are made in Japan were rice and women. So all of the clothes I was wearing, even during the war, were made in USA. And we were the only family in this town who had a ten vacuum-tube big RCA radio, with which we could listen to shortwave broadcasts. So a few times a Japanese “Kenpei” (MP) came to our house to make sure we're not spies or anything like that. Another remarkable thing was that I was the only boy in that generation who refused a buzz-cut hairstyle. Every Japanese male, including the Emperor, the Crown prince, my brother, my father, had a buzz-cut hairstyle. In the kindergarten I went to, the mistress was a very progressive woman. And she allowed me to have my hair long. Amazingly, my male classmates never hazed me because of my long hair. This was true in my grade school too—the kindergarten and grade school were both co-ed. As for barbers, at the beginning they tolerated me but then as the war continued they refused to cut my hair. So I had to take a train to the next town, which I did, where my kindergarten was located and Chinese barbers were still allowed to do business. At the later stage, probably in mid-1944, all foreigners were treated very badly. But still they cut my hair. But then I think the last year of the war, they were all expelled. I didn't have a place to go for my hair cut. But then my mother found a friend of hers in our town who opened a barber school in her home, which was within a walking distance from our home. So she was happy to have me as a customer. Even then, a Japanese MP came to our house asking my mother why your son wasn't like everybody else. And she replied something like, "Well that's how he wants it and he's just a small boy," and he laughed and left. When the war ended in August and my school resumed in September after summer recess, I noticed our principal and my teacher no longer had buzz-cut hairstyles. But I was just remembering because tomorrow [is the anniversary of when] the war ended.

Hochheiser:

Yes.

Iwasa:

I was re-telling my wife this morning that when the war ended, it was the first time the emperor spoke on the radio, and amazingly, no one had a radio around our house. So our neighbors came to our house to listen to the emperor for the first time talking through this RCA radio. Another thing is our family was the only family in the town who had a refrigerator and a washing machine, both by Toshiba, but later Toshiba people told me they were just copies of GE machines. I think Toshiba bought a lot of technologies from GE in those days. Even our family doctor didn't have a refrigerator. So we had to keep some of his medicines in our refrigerator. But I don’t think I ever saw the washing machine used. That was Japan before and during and right after the war. Another thing there was a real food shortage. That's why my parents' choice to move to this location was fortunate because our town was surrounded by farmers. My mother also came from a fairly wealthy family. So she had lots of good silk kimonos and obi and these farmers, of course, they didn't have, let alone seen, any of these. So she traded all of these for food. And so we didn't have any food shortage and we were lucky. And another remarkable thing she told me after the war is that just after the war had started, she visited her former college teacher in Hirakata, a small city outside Osaka, and on her way home she found in a grocery store in the city two or three cases of Mazola Oil, which she bought and had them delivered to the home.

Hochheiser:

Yes.

Iwasa:

So we had tempura with the enemy oil during the war. This may be the reason why tempura is still my favorite Japanese food, especially when each piece is served one at a time as we finished the piece. Of course, in good tempera you use the oil once or twice and recycle it for other cooking. But during the war of course, she used the same oil for tempera about six times, until it because unusable for tempura. During the war you couldn’t keep an in-house maid, but we had one. Towards the end, the rule became very strict. So we had a maid come every day in the morning and go back in the evening. And my mother used to give the maid the over-used oil but she was so happy, saying it tasted much, much better than the government rationed cooking oil. Anyway, my mother wanted me to go to America even before the war ended.

Hochheiser:

Right.

Iwasa:

At that time Japan had zero hard currency. The only way to come here was through a fellowship. So most scholars and students all came here on Fulbright scholarships or other fellowships. And some of my classmates came here under Grew Fellowships, I think named after the U.S. Ambassador to Japan, Grew. I didn't want to apply to any of those fellowships. My parents didn't even encourage me to try to get a fellowship. They decided to finance my education privately. Of course, it was very difficult to get dollars. The only way was through the black market and one dollar then was like 400 yen. The official rate was 360 yen. But because we had a very nice house—it was surrounded three sides with a tall (about 8 feet) and thick dirt fence, capped with black titles like those of temples, not uncommon for old houses outside of Kyoto city district. In fact, many samurai movies were shot outside our house. Even John Wayne after I came [to America]. And my mother always treated guests well and she told me John Wayne had tea in the dining room. And so I said, "Where is the proof?" “No, I don't take any pictures or seek autographs.” I may be carrying her DNA on this, because I now never take a camera with me, though starting in my senior high school, I became a picture-taking fanatic after my father gave me a Leica, which, I later found was made in 1938, the year I was born. In those days, American visitors to Kyoto were all wealthy, looking for antiques. And the mayor then of Kyoto whom my parents knew well suggested that my parents meet these people because he knew we needed dollars. And my mother took them to really good antique shops--there were a lot of antique shops in Kyoto but most of them sell junk-- but the one she knew well sold only genuine stuff. He sold to national museums, and much later to the most important museums abroad. So she took some very wealthy people to him. In those days no checks or credit cards were used in Japan. Besides he took only cash. So when they were ready to buy in dollars, my mother said, "Well I'll pay in yen and you give me the dollars.” That’s how my parents accumulated lots of dollars.

And then the mayor said, well there are some visitors who like to stay for a period of time, like two months or six months or even a year in a nice Japanese style house. You have a very nice teahouse and you have maids. So maybe you can let a foreigner (in those days nearly all Americans) stay in your house for a fee—in a way a part of our house became a bed-and-breakfast inn, except every dinner was served and most visitors stayed for a period up to one year. And most evenings the visitor had to have dinner with us, for us to learn English. So that's what my parents started doing while I was still, I think, in junior high and this continued through my senior high school years. Initially we had a lot of missionary women because Doshisha's a Christian school, although I didn't become Christian. And then later on there were some scholars. I even remember there was one from B U. And then there was a woman, Miss Gertrude Glauser from Salt Lake City. Early on most one-afternoon American visitors, except those from the West Coast, Midwest like Chicago or the East Coast, used to ask my parents many ridiculous questions. So they said they didn't want anyone except those from the West Coast, Chicago area, or the East Coast. But then there was this woman from Salt Lake City. See, when Miss Glauser began staying our house, my brother already was here, studying at Westminster College, Salt Lake City, a small non-Mormon school, before moving to another school—he eventually returned home. When my parents heard the woman was from Salt Lake City, they of course welcomed her to stay in our house. So Miss Glauser was in our house when I was in senior high school. Then my parents started telling her that they wanted me to go to Harvard, Yale, Princeton, or Columbia. These four universities were the only American universities they’ve heard of. And they thought I could get in without any problem. And then after staying in our house for a few months, Miss Glauser told my parents, “No, Yuki should go to MIT.” My parents, they weren’t science oriented at all, never heard of MIT. But she assured them, you know, MIT was the place Yuki should go. So my father said, "Well you go to MIT.” And then she suggested, you know, going straight from Doshesha High School to MIT might be very difficult for me and suggested I should first go to the Westminster College. My brother was already there. So I spent one year there. Then I applied to MIT and was admitted. Miss Glauser is still alive and amazingly doing well till this day, and since about ten years ago, every October my wife and I visit her in Salt Lake City. She’ll be 100 next February.

Studying at MIT

Hochheiser:

And how did you end up taking your undergraduate degree in mechanical engineering there?

Iwasa:

When I was in high school student, my parents had a lot of business friends. And I used to say I wanted to become a banker. And one of my mother’s friends’ husbands was a prominent banker. So he assured my parents I could get into his place. But then Miss Glauser told my parents I should attend MIT. My brother is very, very mechanically good. He said well then if you're going to MIT, you have to study mechanical engineering. That's all he told me, because I never built radios, not even changed a light bulb. Nothing, mechanical, electrical, or scientific. And I went to MIT. I still remember in my sophomore year when I took a thermodynamics course. And the first quiz had a problem about a capacity storing energy and discharging it through a resister. And the question was “is this a reversible or an irreversible process?” It's of course irreversible. But I didn't know what capacitor was. So I raised my hand during the quiz. I asked, "Professor Fay what is this capacitor?” And he said, "Don't you know what capacitor is?" “No.” “It’s a device that can store energy.” Okay. I had zero background in engineering although I studied physics and math and chemistry and biology in my senior high school. And in Westminster College, chemistry and physics. So my interest in engineering was absolutely zero. I just went to MIT because my parents told me so. And my brother told me to study mechanical engineering,

Hochheiser:

You must at some point decide that you liked it.

Iwasa:

Yes, I guess I wasn't still sure if I wanted to be a professional engineer because I always knew that when I returned, I could become a banker. I think what changed me was that the summer after my sophomore year when I worked in the Cryogenic Engineering Lab at the time headed by Professor Sam Collins. The first job he gave me was to paint his lab with another student from Nigeria, his first name was Sylvester but I cannot recall his last name. So two of us did the painting. I think it took us one week, maybe two weeks. And after that Professor Collins said, "Why don't you become my assistant?” Professor Collins was a kind of guy who did everything himself. He was a very distinguished professor, who played a key role in making liquid helium available in large quantity. And he's the one who taught me superconductivity, showed me liquid helium, all that kind of thing. Everybody gets interested in superconductivity when told you need no power to sustain current, so I got interested in superconductivity too. But of course that was only during the summer time.

Hochheiser:

Right.

Iwasa:

But then when I was looking for my thesis advisor in the beginning of my senior year, I went to the ME department headquarters and there was a woman, Miss Muffet and I asked her about a professor I should do my thesis—see even then I really didn't know what I wanted to do.

Hochheiser:

Yes.

Iwasa:

And then she said, "Well Yuki, for you, you should work for a professor who has a lot of money.” I don't know why she said that. And I asked her who that might be in the ME department. And she went something like this. “Oh, that's Professor Collins because he gets all this free helium from the Navy. And he sells all this liquid helium within the campus and to Lincoln Lab. So he has a lot of money. So you ought to go and ask if you can become his thesis advisee.” And I went to see him and he remembered me well and said, "Oh no problem. Yes, you can be my student." that's how it started.

Hochheiser:

So what was your thesis on?

Iwasa:

Well then of course he said I had to do something in superconductivity.

Hochheiser:

Right.

Iwasa:

But he didn't actually know too much about superconductivity. Because my grades were quite good at that time the department put me in the honors program, which required the honors program students (five of us at that time) to write in two years a thesis for both bachelor’s and master’s degrees.

Hochheiser:

So after five years, you get both a bachelor’s and a master’s at the same time?

Iwasa:

That's right. MIT offers the same subjects for seniors and for graduate students. And during our senior year we had to take equivalent grad courses. At the same time, most of my friends were electrical engineering majors because at that time electrical engineering was a hot subject. Although to me mechanical engineering is most basic in engineering, yet at that time I didn’t think it was really hot. So I took essentially all of the electrical engineering requirements at the same time, except one lab course.

Hochheiser:

Right.

Iwasa:

You know, nowadays some students complain having too many exams. But, I had seven finals one time. In those days they let you take as many courses as you wanted. Now I think they restrict it. Anyway Professor Collins said I ought to have another advisor because I was going to do my Bachelor’s and Master’s thesis in superconductivity. The only electrical engineering professor I knew quite well was Professor Paul Gray who much later became the president of MIT. But at that time he was an assistant professor. I took his course and I did very well. So anyhow, I went to see him. He said, "Oh of course, no problem.” So I had two advisors because superconductivity involved liquid helium and electric and magnetic experiments, and my thesis topic was magnetization of superconductivity. That was a very hot subject in superconductivity at that time.

Hochheiser:

I gather you got three degrees at the same time?

Iwasa:

At the end when the graduation came around, I asked Paul, I have taken all of the electrical engineering subjects, is it possible for me to get a bachelor's degree in electrical engineering? And Paul said, "Oh yes, I'm almost sure but you have to go to the department headquarters.” There, I met Professor Truman Gray, not related. He had all my records in electrical engineering subjects, including some grad subjects. Professor Gray told me “Yuki, I see you did very well in Course VI subjects. Except I see you didn't take one required undergraduate lab course. So I don't think we can give you a bachelor's degree. But I'd be happy to give you a master's degree.” I said, "Thank you sir." That's how I ended up with three degrees.

Hochheiser:

Then you continued on for further studies at MIT?

Iwasa:

Yes, Paul wanted me to continue. Another thing: Paul’s specialty was not superconductivity at all. His specialty was the thermoelectric effect, electricity from a temperature difference. The only reason he agreed to be my thesis advisor is I guess because we got very friendly and he wanted to remain my advisor. But he didn’t have a good thesis topic for me and he arranged me to get connected to Bruce Montgomery in the National Magnet Lab.

Hochheiser:

So this was your first contact with the lab where you spent your entire life?

Iwasa:

Right, yes. As I wrote in 2012 for a Japanese organization (Forum of Superconductivity Science and Technology), I went to see Bruce Montgomery, the day John F. Kennedy was shot. MIT officially closed at 3:00 p.m. Everybody was running around and I had an appointment with Bruce at 4:00. I went there and Bruce had tear in his eyes and we really didn't have any interview to speak of. But probably due to Paul's recommendation, he decided to take me as a full research staff.

First Years at the Magnet Lab

Hochheiser:

Okay. So then in the fall of '63, you become a member of the staff of the Magnet Lab?

Iwasa:

Actually it was beginning the fall of 1964. The reason I can remember all this is because I wrote those things in the Japanese article, in English.

Hochheiser:

Mm-hm.

Iwasa:

Mike Walker (my former classmate, then at the Westinghouse Research Lab in Pittsburgh) and I were independently doing this magnetization study and then Bruce Montgomery showed me this article written by Mike and John Hulm. Hulm was very famous in superconductivity. He should have been interviewed but I guess he had passed away before this program started. Mike Walker was a real good friend of mine; we drove all the way to LA together as undergraduates. I was totally surprised that one of my classmates, and not only a classmate but also a very good friend, happened to be doing superconductivity and in the identical area. We didn't like their [Hulm and Walker] interpretation of their experimental results. And so Bruce said, "Maybe you ought to further investigate this.” And that's how I decided to choose that as my PhD thesis topic. I went back to Paul and he said, "Okay, then why don't you just become a student again?” And that's how I returned to do my Ph.D. work as a research assistant. I began in February 1966 as a Ph.D. student. Then began my thesis full time in summer 1966 and finished it in April 1967. So I was a Ph.D. student for a period of fourteen months.

Hochheiser:

And your dissertation was on?

Iwasa:

On magnetization of niobium zirconium superconductor.

Hochheiser:

Okay.

Iwasa:

Yeah.

Hochheiser:

What was the magnet lab like in the 1960s during your early years on the staff?

Iwasa:

Oh it was flush with money. Well, the very first interview was of course with Bruce Montgomery. But when I officially began in September, I still remember when I met this grad student, I think, in physics, David somebody, said, “welcome to the land of plenty.” Because, I don't know about now but in those days, most equipment in the EE department was very old. You know, MIT is an old university and at least at that time with much antiquated equipment.

Hochheiser:

Yes.

Iwasa:

And if you go now to Korea or Japan, any place, the building itself is ten times better, more impressive than what we had at MIT in those days. I remember much later when two Korean visitors came looking to fund research projects at MIT. This is in the mid-1990s. And they came to the Magnet lab. They were interested in superconductivity. So I said, well you should also visit Professor Joseph Smith at the cryogenic lab. Professor Smith succeeded Sam Collins. I don't think you've been there. It's like a very old museum; everything then looked old. The two Korean visitors said, “Yes we did, but the lab was so old looking and so museum like, we didn't want to support anything there even though Professor Smith is one of the most brilliant engineers and innovators and has a lot of good ideas.” Simply because how it looked, they didn't want to do anything. And the Magnet lab wasn't that bad, but still it wasn't that impressive either. But anyway, during the early years, the Magnet lab really had everything because it was funded by the military. A military funded lab is usually very well equipped. Much later on, one of my students got a job in Lincoln Lab which was also funded essentially by the military. And he called me back one day and said "Yuki. You know, in your place if we want a pen or notebook, you go down to the supply office and they give it to you for free. Well in the Lincoln Lab, you go down to the supply office and you can just pick any computer you want.” That kind of thing. As an experimentalist, I always wanted to have my lab well-equipped.

Hochheiser:

So you finished your doctorate in a period of about fourteen months while you were working at the lab.

Iwasa:

I of course had an early start because I got my masters in 1962. And then I worked on essentially the same subject until 1964. During that time, I was in the Magnet lab.

Hochheiser:

Right.

Iwasa:

Then, officially I became a member of the research staff.

Hochheiser:

In '64?

Iwasa:

That's right. Some of the things I did during that period, of course was a good introduction to my thesis work, but all the experimental results I used in the thesis were done in this period of fourteen months.

Hochheiser:

Did your status at the lab change once you earned your doctorate?

Iwasa:

No.

Hybrid Magnets

Hochheiser:

And how did your work proceed? Did you continue in the area of your dissertation?

Iwasa:

The Magnet lab was created to focus on two areas, solid-state physics, specifically, semiconductor, and magnet technology, specifically, to advance high-field magnet technology. Solid-state physics, especially at that time semiconductor was the founding director Professor Ben Lax’s specialty.

Hochheiser:

Okay. Not superconductivity?

Iwasa:

No. But because solid-state physics required a high field, the magnet technology division’s initial focus was to develop higher field magnets. That's how my boss and mentor Bruce Montgomery came up with this idea of hybrid magnets. Now I want to also give credit to Martin Wood who founded Oxford instruments. Martin and Bruce were very good friends. Martin used to visit MIT and I think Martin used to stay at Bruce's house. And that's how they came up with the hybrid magnet idea of a copper magnet inside and a superconducting magnet outside. Because one of the most important aspects of a superconducting magnet is that it can generate a field with a very small amount of power, i.e., the only power needed is for refrigeration. And therefore we can generate a large field over a large volume, limited of course by the critical field and the critical current of the superconductor. It was a very clever idea. On the other hand, a Bitter magnet which is water cooled, consumes lots of power and so you want to make it as small as possible because the power consumption obviously scales with volume. But it has no intrinsic field limit unlike superconductors. The field could go up to 50 teslas if it wasn't for the mechanical stresses. So what they decided to do is to make the power hungry water magnet as small as possible, put it inside a high-field background of a superconducting magnet outside. That's how the hybrid concept was born. Until then the entire activity of the Magnet Technology Division was on water magnet technology that Francis Bitter developed in the 1930's. Bruce hired me because he, I guess, foresaw a need for somebody who would specialize in superconducting magnets. My theses were all on magnetization of superconductors, which was related to operation of superconducting magnets and that's how I was rehired just as the first hybrid magnet project was being planned.

Hochheiser:

And but when did it begin?

Iwasa:

It began in 1967 after I got my Ph.D. I remember accompanying Bruce to a conference in Cleveland in 1968 when he, I think, officially presented the hybrid magnet concept for the first time. I don't remember what kind of conference it was. It wasn't applied superconductivity. And of course in those days, there was no need really to write proposals because, you know, the Magnet Lab used to be funded by the military. However, the funding situation became challenging beginning around that time. Because of the Vietnam War, there were a lot of protests against military funded research.

Hochheiser:

Right and a lot of it right at MIT.

Iwasa:

At that time MIT had a lot of military funding. The biggest casualty, I don't know if I should call it casualty, was the Draper Lab, which was funded 100 percent by the military. And so Draper Lab became independent from MIT. The Draper Lab and MIT still have some connection, but I don't know what kind. It's no longer an MIT lab. The Lincoln Lab also had a division which was solely military. That section was separated from the Lincoln lab and became an independent entity, Mitre, M-I-T-R-E, which stands for MIT RE(search).

Hochheiser:

Right. I am familiar with the company.

Superconducting Magnets for NMR and MRI

Iwasa:

Going back to my freshman year, my freshman advisor was Professor Francis Reintjes who was quite prominent. His office was in Building 20, a leftover lab complex from the Radiation Laboratory created during the Second World War to develop electronics technologies, and it was a restricted area only for the U.S. citizens. Because I was a Japanese citizen, every week when I went to see Professor Reintjes for a weekly meeting, I was checked by the guard and he allowed me to enter the restricted area. After all, I was just an innocent-looking freshman. In those days, MIT also offered courses restricted only to the U.S. citizens. And so in 1968 two things happened. One, Bruce gives a paper talking about the hybrid magnet. And two, economically times get harder at the labs because of the Vietnam War.

Yes so then finally the MIT decided not to have the Magnet Lab supported by the Air Force Office of Scientific Research and the NSF began funding it. And after that it became financially difficult. But nevertheless, we didn't have to, maybe Bruce had to, write any proposal to build the first hybrid magnet. The hybrid magnet project continued until the national magnet lab ended at MIT in 1995. I was involved from the very beginning, with the first hybrid magnet project. But I also was quite much involved in stability of superconducting magnets. Actually in those early years, in the 1960s, everybody wanted his magnet to succeed and made sure the magnet performed as designed. So these magnets had a very generous cooling, with plenty of helium passages within the winding. And that's how John Stekly’s stability theory became very popular. Much later I learned from John that he too was in the ME honors program. Now, the only people who still use Stekly cryostability design concept are fusion people. But in other applications, especially in NMR and MRI, it is inefficient to have helium within the winding. Not only doesn’t helium carry current; it also uses precious winding space. And mechanically liquid helium doesn’t do anything. So the best way is to get rid of helium and make the winding essentially adiabatic. Adiabatic means no cooling within the winding. When people hear adiabatic, they ask how can an adiabatic superconducting magnet be cooled because it needs cooling. The winding has no cooling channels within, i.e., no local cooling. But its outer surface of course is surrounded usually by liquid helium.

Hochheiser:

So the, the cooling is just--

Iwasa:

Outside. But once you surround the winding with liquid helium, if there is no dissipation within, its temperature of course becomes uniform; that's how the adiabatic magnet operates. But as soon as there is energy dissipation, say, by a disturbance inside, then because there is no cooling this section of the winding can be heated up, and it may lead to a quench of the whole magnet.

Hochheiser:

Right.

Iwasa:

Otherwise it’s a very efficient magnet because it is compact, it uses less conductors. And the overall size is smaller. It’s ideal for MRI and NMR magnets. So that's how the application of adiabatic stability concept to NMR and MRI started around the early 1970's.

Hochheiser:

Okay. We need to stop for a minute to change the tape.

[End tape 1; begin tape 2]

Hochheiser:

Okay. When we stopped, you were talking about developing magnets for NMR and MRI in the 1970s.

Iwasa:

Right. We actually began very earnestly around 1980. Another big development was that Bruce Montgomery foresaw that NMR and MRI would be a future for superconducting magnets. So he invited John Williams to the lab. In fact, John came to the lab as a visiting scientist in 1964. He was actually my day-to-day supervisor when I was doing the Ph.D. work because at that time Bruce was in Switzerland writing his famous book on magnet design. Then in 1968 John returned to England and, I think, went to work for Oxford Instruments. And in 1973, I remember Bruce sent me to two conferences in Europe and urged me to stop by at John Williams’—and I stayed in John Williams’ house two nights on my way home. Bruce told me to try to persuade John to come back to the Magnet Lab, which I did. So in 1974, he came back to the lab, this time, for good. I still remember it was just before or after Nixon resigned. His first mission was to build a 500 megahertz NMR magnet, I think the very first 500 in the world. And we had a lot of problems, because it was an adiabatic magnet, which quenched often. So I was assigned to investigate very fundamentally about the sources and mechanisms of quench in the adiabatic magnet. I was also in a hybrid magnet project. We built altogether, I think, six or seven hybrid magnets. My very close colleague, Mat Leupold, a great mechanical engineer, and I began car-pooling in 1972, before the first oil crisis, and I remember quite vividly that most design details of our hybrids, including my usual rough numerical estimates, were mainly done in the car during commuting time. The car-pooling continued uninterrupted until Mat retired in 1993. But at the same time I was studying stability for adiabatic magnets. And that's how I spent most of my time until the discovery of HTS and then I think I'm one of the very first people to get out of stability study because with HTS I immediately realized stability was no longer an issue. Actually, it still remains an issue for LTS magnets. We thought we came up with a very good method to essentially eradicate these quenches, which we call premature quenches, quenches before the current reaches the design point. But I know many magnet engineers, especially those at magnet vendors, still have to deal with quenches, although not as bad as used to be. But by the late 1980s my interest essentially shifted to HTS.

HTS (High Temperature Superconductivity)

Hochheiser:

Was this almost immediately in '86 when you learned about it?

Iwasa:

Well it was I think discovered in 1988, right?

Hochheiser:

Müller and Bednorz published their work in 1986.

Iwasa:

Okay. But I think HTS became a really hot subject after Paul Chu and his people came up with YBCO.

Hochheiser:

Okay.

Iwasa:

You see the IBM guys discovered the existence of superconductivity around 40 kelvins. For engineers, you know, 40 K is still not high enough. I mean it had to operate at [liquid] nitrogen temperature.

Hochheiser:

Right.

Hochheiser:

So it was the YBCO a couple years later at liquid nitrogen temperature that caught your attention as something worth pursuing.

Iwasa:

Not only me, but a lot of people. But of course at that time, YBCO was just in bulk form, which is really not suitable for winding a magnet. But immediately after YBCO and I think it was in 1991 BSCCO came in the form of wire or tape. That was really revolutionary to the magnet engineer. Because with the bulk form you cannot do much.

Hochheiser:

Right.

Iwasa:

But YBCO really publicized superconductivity, because lots of people saw that thing floating.

Hochheiser:

Right; if you go look on YouTube, you'll see it.

Iwasa:

Yes. But I think the discovery of BSCCO was a really big deal for us. And of course at that time, we still were operating the National Magnet Lab and had the highest DC field. So we measured its critical current. Sumitomo Electric was one of the early people who start making useable tape.

Hochheiser:

Right, These are BSCCO tapes.

Iwasa:

BSCCO tape. We collaborated with Sumitomo Electric, though no money was exchanged. The magnet lab was always available to any qualified people who wanted to use our high field facilities. So Sumitomo people came and we made a lot of measurements. And we were I think the earliest group to perform these measurements in a very high field. We made a small coil exposed to a very high background field. We had a world record. We did quench propagation measurements for HTS, which some people still do. We did lots of pioneering experiments with HTS in those days, thanks chiefly because we had high field facilities.

Hochheiser:

So these, these are experiments are now working on HTS magnets.

Iwasa:

Yes. And then we lost our status as the national magnet lab.

From National Magnet Lab to MIT Magnet Lab

Hochheiser:

To pursue that: what did it mean to be the National Magnet Lab and what did it mean to no longer be the National Magnet Lab?

Iwasa:

Well to MIT really it was a headache because MIT really wanted to train future scientists and engineers and educators. Our facility was just a facility. So no students were directly involved. But MIT had to provide a lot of support; of course MIT didn't do anything for free. But now the NSF funding was not growing at all. It was a very difficult time.

Hochheiser:

Right.

Iwasa:

One of the things that happened just about the time HTS was discovered was that Japan had an economic boom, a bubble economy. So they could afford to do almost anything they wanted. So they decided to build a magnet lab that would outdo MIT. MIT was a standard in Japan for everything technical and scientific. When I first went back to Japan after I got my PhD, I was invited to visit a lot of companies, Toshiba, Mitsubishi, and most of them said, you know, Yuki, we thought MIT people were God. And I said, now you see me, I'm not God. That's why it was astonishing that my parents didn't know or never heard of MIT. This was in a way true here in this country too. I first got a car in Utah, Salt Lake City, the spring of 1957, because I wanted to come to MIT driving my own car. I paid in cash and the manager asked me, okay, so what were you going to do with this car? I said I was going to the East Coast to study. He said “where?” I said MIT. “What is MIT?”

Hochheiser:

So, MIT found that running the National Magnet Lab didn't really fit in.

Iwasa:

Well the lab was struggling and MIT had tuition higher than those of other universities but wanted NSF to pay research assistant’s MIT tuition 100%, i.e., MIT refused to contribute, for which NSF wasn’t happy. And yet NSF was one of the biggest funding agencies for MIT. So there was always some kind of animosity going on. I think that’s when Jack Crow [first director of National High Magnetic Field Lab., FSU] saw the opening. Going back, Japan decided to create a big magnet lab in Tsukuba with a goal of building a 40-class tesla hybrid magnet, which would beat our 35-T hybrid then under construction. So because of that big news, NSF or the National Research Council created a special committee, headed by Frederick Seitz, a famous solid-state physicist. The conclusion was that the US should have a magnet lab much bigger than the Tsukuba magnet lab. And of course MIT thought the one at MIT would be greatly expanded under this new initiative. And yet we lost to the Florida State U. It was a really big shock. And so, that's how the facilities at MIT ended.

Hochheiser:

But the magnet lab continued?

Iwasa:

Well then it went from the Francis Bitter National Magnet Lab to the Francis Bitter Magnet Lab, Francis Bitter added to the National Magnet Lab in 1967 in honor of Bitter who passed away late that year. MIT did research and found that in the entire world, high-field solid-state physics was not that big, only about 300 people at most. Whereas NMR is huge compared with that. Because the magnet is a vital component for NMR and MRI too, MIT decided to shift the focus to NMR.

Hochheiser:

So at that point the focus shifts to NMR and MRI which even today have the most widespread applications.

Iwasa:

Of superconductivity. Luckily for us.

Becoming a Research Professor

Hochheiser:

And around this time in 1992 you became a research professor?

Iwasa:

Yes, well my former director Professor David Lister gave me that title.

Hochheiser:

Now at what--was it around this time when you started teaching and having students?

Iwasa:

A commission was created in the late 1970s that noted that there was so much good research going on in these special labs. So they decided to create the senior research scientist status with a three-year rolling tenure. If you look at the MIT description of this position, the position is equivalent to full professor except there is no mandatory teaching duty, but we were encouraged to do some teaching, and I was included in the Department of Mechanical Engineering. And when Paul Gray, my former advisor, became president in 1980 they created this position and I was one of the very first ones to get the senior research scientist status. And when David Lister gave me this research professor title, I asked Paul, “why don't you create more research professors?” And Paul said “Yuki, then 90% of professors would want to devote only to research and we won’t have enough instructors.” So after I became affiliated with the ME department I started teaching officially in the early 1980s. It was funny, when this position was under consideration in the late 1970s, Ben Lax came to my office. “Okay. Yuki, you are one of the very few we will nominate for this position. And I'm going to nominate you in the Department of Electrical Engineering” because he knew I had a Ph.D. from the department. I told Ben I wanted to be affiliated with the department of mechanical engineering. He said, "What? I thought you had a Ph.D. in electrical engineering.” And I told Ben that in magnet technology, if you really want to build a good magnet you have to be a good mechanical engineer because in the end it's a mechanical integrity that is the most important aspect of a magnet or for that matter any device. So I wanted to be affiliated with ME. And I start teaching an undergraduate lab course. And I can say why Paul says most professors, if given a choice, would want to be research professors. Teaching's a really time consuming tedious job, you know.

Hochheiser:

Well teaching?

Iwasa:

Yes.

Hochheiser:

I have done my share of teaching and it's very time consuming.

Iwasa:

And I enjoy teaching the students who are smarter than me. But MIT also has changed admission policies with time. When I was admitted, MIT admitted only nerds. Then when HTS was discovered, I thought I should offer a graduate course in superconducting magnet technology and I proposed it to the department. And they said oh no problem. Why don't you just go ahead? And in the early days, I had lots of students, fifteen, sixteen students every year. Then around the mid-1990s, it became much smaller and the department head called me up and said, well Yuki, I think you shouldn’t be offering this every year. So that's how I began offering the course every two years. Now we hardly get any students. Now most of superconducting magnet students are either Chinese or Koreans. I went to Cambridge U. this summer. I met Tim Coombs. He has a fairly big superconducting magnet group. I think he has about sixteen, seventeen students. He said sixteen of them are Chinese.

Hochheiser:

Yes. That's interesting. Now as part of your teaching, did you have your own Ph.D. students?

Iwasa:

Yes, I had, but not many. How many got the Ph.D. in superconducting? I think I can count maybe five or six. It's not really popular. You know, everybody wants to be in robotics or nanotechnology, things like that. A big problem with superconductivity is that you don't become wealthy. That's important for most college students.

Hochheiser:

After the magnet lab refocused on NMR and MRI, did that change the direction of your own work?

Iwasa:

Yes.

Hochheiser:

What did you stop working on and what did you start working on?

Iwasa:

Well number one, there was nothing to stop working on because everything was stopped. Okay. Until then, the mission of the Magnet Technology Division was to build higher magnets, especially hybrid magnets. With the arrival of John Williams in 1974, we started building NMR magnets. But in 1995 when the FBNML became FBML most people had to leave.

Hochheiser:

Did a lot of the people move to Florida State?

Iwasa:

No, only a few. Fortunately, for the first time, MIT offered an early retirement package. And if you had worked at least ten years and were over fifty-five years of age, you could retire in 1996 with a generous package. So in the Magnet Lab, if you had no support you took that package and left. I was the only one left in the Magnet Technology Division. Technicians took the package and left. And, luckily I had teaching duty plus I had my own research program funded by DOE. When we decided to do mostly NMR, I started getting funding to build NMR magnets right away.

Nuclear Magnetic Resonance (NMR)

Hochheiser:

So now if you could talk a bit about your NMR work in the 1990s.

Iwasa:

Yes. Well the first thing I realized was that NMR people always want higher fields. The goal at that time was a proton frequency of 900 megahertz. They were trying to reach 900 megahertz with LTS. I knew the top frequency would be going forever higher and higher. And if we’re going to go beyond gigahertz, simply because of the limitation of LTS current carrying capacity, we have no choice but to use HTS. So I was one of first people, if not the very first, to propose to build a gigahertz magnet using HTS in the high field part of the magnet. And I loved this idea of combining LTS and HTS. You know, the NIH review panel gave me one of the best percentiles, I think it was 3.9, for Phase 1 of a 3-phase proposal to build a 1 gigahertz LTS/HTS NMR magnet, submitted in early 1999. One reviewer saying, I shouldn’t have been too modest to apply only a two-year phase one program, and instead should have applied for a five or ten-year project to complete the whole magnet. So anyway, we got the funding right away. Of course, we were lucky. At that time I think President Clinton and the congress decided to double NIH funding over a period of about five years starting about 1995. So NIH had lots of money to support many projects. So that's how this 1G program began and has continued. In 2007 they asked me to upgrade the frequency from 1 gigahertz to 1.3 gigahertz, which corresponds to a field of 30.5 teslas. Now the funding situation is really tough. The NIH budget hasn't really increased in over the past ten years.

Hochheiser:

So, so how did, how did your work with using HTS create bigger fields for NMR?

Iwasa:

With LTS, the practical limit is a gigahertz. Actually Bruker amazingly built an all LTS gigahertz magnet, I think in 2010. It was delivered to a French lab. I don't know how many more they have sold since. It's a very expensive magnet. And now they are also following our steps to go to a higher field. They have customers for 1.2 gigahertz magnets.

Writing "Case Studies of Superconducting Magnets"

Hochheiser:

Stepping back a bit, what led you to write your book on Case Studies of Superconducting Magnets?

Iwasa:

In 1989 I began offering an ME graduate course called “Superconducting Magnets.” I usually want to do everything myself. I created many, many homework problems, all but one by myself, quite difficult and time consuming elaborate ones. So I had piles of those things in my file. And then when the Magnet Lab lost status as a national lab, I jokingly told to my assistant director Don Stevenson I was going to write a book with my name above Francis Bitter National Magnet Lab so that FBNML would remain, at least in my book. And he thought that was a good idea. I wrote it very fast. I don't know how one starts writing a textbook. I think one would model similar books by other people. I just went ahead but forgot a lot of topics to include. But the book became quite popular and, and I found writing a textbook makes you well-known. Perhaps because of the book I got an invitation in 1996 to spend one year in Keio University. I was always at MIT. And I accepted this invitation from Prof. Sawa only because of the internet, which allowed me to communicate quickly and easily. Otherwise I could not have left MIT in 1996. And also because of the advent of much more activities in HTS, which weren’t included much in the first Edition, I decided to write the second edition, adding important topics that I forgot to include in the first edition. And that one took me over ten years.

Hochheiser:

Whereas the first edition was fast?

Iwasa:

Well I did it in twelve months. Very fast.

Hochheiser:

Why did it take so much longer? Were you too busy working?

Iwasa:

No, because this time I did lots of derivations, elaborate ones, very elaborate, some of them unnecessary. Now I'm trying to write a handbook because when I use a textbook, I don't care how a formula was derived. I just want to know the formula. So I plan to finish a handbook that lists just useful equations and tables for magnet design, most of which were derived in the second edition. But some of people, when told of my handbook project, said “Yuki, the best part of your book is all those elaborate derivations.”

Hochheiser:

It all depends what you want.

Iwasa:

I guess. Yeah.

Research on Magnesium Boride for Superconducting Magnets

Hochheiser:

What led you to begin working with magnesium boride in addition to your work with BSSCO tapes?

Iwasa:

Well, MgB2 was discovered in 2000. And then in 2002 or 2003 Mike Tomsic who has a company, HyperTech Research that manufactures MgB2 wire, called to tell me that MgB2 had a great future in magnets. But, with due respect to Mike, I didn’t take his opinion on MgB2 seriously. At around that time, I went to visit Hitachi, which is an established company, with a long history of superconductivity. I went to the Hitachi research lab and met Dr. Michiya Okada. Dr. Okada was very enthusiastic about MgB2. He told me how this could change things, especially for MRI magnets. And I thought, well if Hitachi people think that MgB2 is good wire then it might be a good idea to get involved. So when I came back here, and Mike kept contacting me to do something, I decided, okay, let's do it. So I wrote a proposal to NIH, a solicited one, though my proposals are usually unsolicited. In this solicitation NIH specifically wanted low cost MRI magnets developed for the third world countries and hospitals in the rural USA. In the solicitation NIH stated at that time (2002) that only 10 percent of the total world humanity benefited from MRI, which is a very useful diagnostic tool for early detection of disease and injury.

Hochheiser:

I know. I've have had the occasion to be in one of those machines.

Iwasa:

In fact, it's only in Japan, the US, and Europe where MRI is extensively used. And even within the US, according to NIH, only in big cities, not in rural areas.

Hochheiser:

Yes, the machines are expensive.

Iwasa:

Expensive and they run on liquid helium. And so forth.

Hochheiser:

Right.

Iwasa:

So NIH wanted MRI magnets developed that could be used in these difficult areas. So I thought MgB2 might be ideal. Without using any liquid helium as a cooling source.

Hochheiser:

Right. You're using liquid nitrogen?

Iwasa:

No. Well MgB2 loses superconductivity at 39 kelvins.

Hochheiser:

So you are well below liquid nitrogen temperatures.

Iwasa:

But you don't have to immerse it in liquid helium. It can be run with a refrigerator. So that was our idea, which we proposed to NIH and we got funding right away.

Hochheiser:

And how has that work progressed?

Iwasa:

Well we are still working on it. Niobium titanium is a really good conductor. Some of the research MRI magnets are seven teslas and nine teslas and even 12 teslas. But for commonly used MRI, 1.5-T is quite sufficient. Now like automobiles, if they want to put a lot of bells and whistles, they can sell it at a higher price. Three teslas are better for the magnet manufacturer because these magnets yield more profit.

Hochheiser:

1.5 gives you plenty for medical diagnostics.

Iwasa:

Oh yes. In fact, when the first superconducting MRI magnet came out, it was 0.5 Tesla.

Hochheiser:

And about when was that?

Iwasa:

This was in the 1970s. And, and all the medical doctors thought it was fantastic, you know, they really loved it. But now, the magnet people are the ones who are pushing to higher fields, like TV, like everything else. MgB2 doesn’t carry as much current as niobium titanium in higher fields. So the advantage of MgB2 is to trumpet about its ability to run between say 10 to 15 kelvins, which niobium titanium cannot do, and reliance on a cryocooler rather than liquid helium. That's a big selling point. But in terms of building magnets, it's more difficult than niobium titanium. So I think it's going to be a struggle. I think niobium titanium will remain the king for a long time. Whereas NMR is not for diagnostic use but for research and for some research a higher field is deemed desirable. But the problem with NMR is that the demand of high-field NMR magnets is not as large as MRI.

Hochheiser:

Well sure.

Iwasa:

There's a very high field NMR magnet like Bruker’s 1.2 G. I think it is priced at $25 million or 25 million euros. It's very expensive. Although there are many prominent scientists who would like to purchase those high-field NMR magnets, they don't have their own money. They have to write a proposal to an agency like NIH, but NIH isn’t exactly flush with money at the moment. In Europe they seem to be more generous with investing in big ticket research equipment. I think Bruker also is facing a tough time. They can build, but they can only sell these magnets at a very high price. And the users who’d like to buy these magnets cannot get funding to buy them.

Hochheiser:

Which puts a puts a limitation on these things.

Iwasa:

Yes.

Evolution of ASC Conferences

Hochheiser:

When did you first attend one of these ASC conferences? Do you recall?

Iwasa:

Yes. I think it was 1964, Brookhaven. [Actually, 1966]

Hochheiser:

That’s the very first one. Did you present a paper?

Iwasa:

Oh yes, I always presented.

Hochheiser:

What was the conference like in the early days?

Iwasa:

Not much different, I guess. I don't remember staying in a hotel. Maybe I stayed in a guesthouse. They have a lot of guesthouses at BNL.

Hochheiser:

Okay.

Iwasa:

I remember attending ASC in 1968 in Tennessee. I remember it was held in a hotel in Gatlinburg within the Smoky Mountains.

Hochheiser:

I guess the real point of my question is to what degree has the conference evolved or changed if at all over the many years you've been going to them?

Iwasa:

The only noticeable thing is that the registration fee just keeps going up. Yet the quality of banquet food hasn't gone up.

Hochheiser:

How about the quality and scope of the papers?

Iwasa:

I would say about the same. Now in a very good gesture, when the ASC in 2010 was held in Washington DC, for the very first time, the ASC invited students to the banquet. You see students are allowed to register at a discount, but until the 2010 ASC they were not allowed in the banquet unless the students somehow got the banquet tickets. I had always thought that wasn't good. Although I didn't initiate it, but applauded this initiative. Maybe it was Bruce Strauss. Anyway I remember complimenting Bruce Strauss about that gesture after the banquet. Happily this practice of inviting the students to the banquet seems to be continuing.

Hochheiser:

Right.

Evolution of Superconducting Magnets

Hochheiser:

Looking back over your career as a whole how has the field of superconducting magnets evolved? I guess you’ve been involved with these things for going on half a century.

Iwasa:

Well superconducting magnets of course need users. And users are quite limited, you know, the high field magnets are either hybrid or for NMR, both of which are exclusively for research. MRI is the only successful application of superconductivity that directly benefits the society. Now the Maglev that a Japan Railways company—one of seven JR companies—is about to begin construction will be another form of a wide use of superconductivity for society. Besides MRI magnets and JR’s Maglev, first between Tokyo and Nagoya by 2030, and then extension to Osaka by 2045, and entirely financed by one of JR companies, it's still quite limited. Another use, though not known to the general public, is in the manufacturing process of silicon wafers. You know, the wafer size’s been getting bigger and bigger. In the process of a growing a large wafer a magnetic field generated by a large superconducting magnet minimizes eddy current induced disturbances, and you end up with a high quality wafer. So, MRI, a Maglev line under construction in Japan, and silicon wafer processing are the only magnet-related applications of superconductivity I can think of that directly benefit the society. Also, some magnetic separation and other advanced medical devices require superconducting magnets.

Hochheiser:

And how have the magnets themselves changed over the years?

Iwasa:

Well I think it's more predictable despite the fact that they do have some quenches. I'm talking about adiabatic magnets. The adiabatic magnets perform, I think, more reliably than those of the 1980s. And I think MRI superconducting magnet business is profitable.

Career Reflections

Hochheiser:

How would you characterize your career as a whole?

Iwasa:

Well I think I have done reasonably well. Definitely, I've thoroughly enjoyed superconductivity. Superconductivity certainly has given me opportunities to tackle many intellectually challenging as well as mundane problems, some of which I believe I contributed to solving them. Met many outstanding colleagues, many of whom have become my good friends. Gone to many conferences in places I wouldn’t have gone except because of superconductivity. It certainly has kept me busy, and probably because of it, quite healthy, physically and mentally. It has also paid my mortgage. [Laughter]

Hochheiser:

That’s very important. [Laughter] What do you see as the most important accomplishments of your career? The greatest satisfactions?

Iwasa:

Well I helped make these adiabatic magnets more predictable. I was a key member of a team at the FBNML in the 1980s that worked hard to make the adiabatic magnet operate reliably, i.e., quenching much less often. I am very proud of those textbooks which many people, at least in this, field, find useful; some even have told me they enjoy reading my textbooks. It’s too bad that our field is so small, so I haven’t been able to sell many [laughter]. I also had many, many people who wanted to come to the lab as visiting scientists to work with me. I keep telling my wife it's not me why many people come to work with me. It's MIT, which they want to put on their resumes. Whatever their motives, I’ve enjoyed working with every one of my visitors and also students.

Hochheiser:

Well I started out with a bunch of cards face up. And now they're mainly face down. So at this point, is there anything that you'd like to add or talk about that, I neglected to ask you about?

Iwasa:

Well, I arrived at MIT in the fall of 1957 as a freshman, and have spent all my adult and professional life here. So, MIT must have liked me and vice versa.

Hochheiser:

And when did you become a US citizen?

Iwasa:

Well I didn't want to become a US citizen because of what the US did to the Japanese people during the war.

Hochheiser:

I Understand.

Iwasa:

Although many American historians rank FDR as one of the greatest presidents of this country, in my humble opinion he did commit an impeachable offense during the war by not defending the constitutional rights of the Japanese who were Americans. Every president swears to do it when he takes his oath of the office of presidency, but in this instance I believe FDR failed. But, you know, the influence of money is very strong. And when my wife found out if I didn't have a US citizenship, the estate tax could be very high. We were advised by a Japanese friend of ours that we ought to become citizens if we were going to stay here. So she first applied for citizenship right away because she was under a wrong impression that she had to be a citizen to be sure to escape a high estate tax. And then she found out that I had to be a citizen too. So I applied in early 2000.

Hochheiser:

So quite recently?

Iwasa:

Yes. Luckily this was before 9/11. So I was given a citizenship I think within six months. I haven't regretted becoming a US citizen of course. We had a lot of technical collaborations with the fusion magnet programs, in which Oak Ridge played a major role, as it continues today. So one time, Bruce took me to Oak Ridge for a technical meeting. They assumed I was a citizen. And then when we were about to go to the meeting, they found out I wasn't. And one of the guards phoned our host “hey we have a problem. We have an alien here. What we going to do?” They solved that very quickly. Then after the meeting we were all going to go to lunch but we had to go through the Y12 building to the cafeteria, a highly classified part of the complex. But, we couldn’t go because of me. So we all went to a restaurant outside and some of the Oak Ridge engineers told me afterwards, “well thanks to you, we had a nice lunch.”

Hochheiser:

But you did not find in most part that you're not becoming an American citizen for most of your career caused problems for you.

Iwasa:

Well no problems, but one time we had a very interesting project, magnetic refrigeration. My mentor and friend, Professor Smith proposed this very nice project to this Air Force guy and I was the PI. In those days, there was no security check, nothing. He assumed I was a citizen. And then about six months or eight months into the program, he called me up and said “Oh Yuki, by the way, are you a citizen?” I said no I'm not, I'm Japanese. And there was a long silence. “Oh, boy” he said. “Well the next continuation, I don't think we can do it. We are just going to finish this one knowing you are a non-citizen.” That's one time we couldn’t get a project continued to the next phase.

Hochheiser:

You had mentioned fusion in talking about Oak Ridge. So did you do some work on magnets for Oak Ridge fusion projects?

Iwasa:

Well recently, I was a member of a review committee so I visited there a few times. But in the past, during the 1970's. I accompanied Bruce quite often to the meetings on fusion programs at Oak Ridge and at FBML. Also in the late 1960s, Bruce came up with an ingenious design concept comprising square “Bitter” copper annulus plates assembled in a toroid. This was in response to a proposal to build, in MIT and, within FBNML, a high-field (~9 T) Tokamak, called ALCATOR, after ALto (high) CAmpus (field) TORus (toroid), coined by Bruno Coppi, a plasma physicist at MIT. The success of first two ALCATORs led to the establishment, I think, in 1977 of an independent lab, the Plasma Fusion Center. So, PFC was spun off from FBNML. Bruce moved to PFC, and upon his invitation I moved my office to PFC, but remained in the Magnet Technology Division of FBNML, headed by John Williams who had succeeded Bruce. PFC later changed its name to the Plasma Science and Fusion Center (PSFC) and operates its famous machine, the ALCATOR C-Mod. On July 1st last year [2013], FBML became administratively a part of its offspring PSFC. In the early 1970s, I worked on stability characteristics of what is known Cable-in-Conduit conductor (CICC) that was first proposed by Bruce and Mitch Hoenig for fusion magnets, and now used in ITER magnets. I think I was one of very first researchers, if not the very first, to perform stability experiments of CICC made of NbTi. As everyone knows, the fusion magnet is another enabling application of superconductivity, but fusion itself is still in the R&D stage.

Hochheiser:

Anything else you'd like to add?

Iwasa:

No, except to conclude this heavily personal account by paraphrasing from the second edition of my textbook. I hope that the future generation will benefit from more things superconducting. Thank you.

Hochheiser:

In that case, I think we're finished. I thank you very much for your time.