Oral-History:Dieter Kind

About Dieter Kind

Dieter Kind

Professor Kind was born into the German community of Bohemia, which became Czechoslovakia, in 1929. At the end of World War II, his father was captured by the Allied armed forces, and Kind's family was forced to leave Bohemia for Germany. In 1947 he began his engineering study at the technical university in Berlin and finished his engineering diploma at the Munich Technical University. In 1957 he received his doctorate in electrical engineering from the Technical of Munich. Kind's research focused on high voltage engineering, particularly the electric strengths of various gases and the breakdown for voltage discharge. After earning his doctorate, he went to work in the high voltage field, designing test and instrument transformers for safe conduction of electric power. He later joined the Braunschweig Technical University for High Voltage Technique and in 1975 became President of the Physikalisch-Technische Bundesanstalt national technical research institute in Braunschweig. Kind became an IEEE Fellow in 1978 for his development of high voltage measurement and test methods. He is a member of the German Physical Society.

The interview spans Kind's career, beginning with his interest and later education in electrical engineering. Kind vividly describes the political, familial, and economic conditions he faced in postwar Germany, and explains how he moved from Bohemia to West Germany during the Allied occupation years. He discusses his research into atmospheric gases and explains the nature of his doctoral research as well as his later work developing high voltage transformers. Kind assesses some of the pioneers in his field and his decision to join the technical university and national research institute in Braunschweig. The interview ends with Kind's discussion of his PTB duties.

About the Interview

DIETER KIND: An Interview Conducted by Frederik Nebeker, Center for the History of Electrical Engineering, 29 August 1994

Interview #227 for the Center for the History of Electrical Engineering, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

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Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, IEEE History Center, 445 Hoes Lane, Piscataway, NJ 08854 USA or ieee-history@ieee.org. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.

It is recommended that this oral history be cited as follows:

Dieter Kind, an oral history conducted in 1994 by Frederik Nebeker, IEEE History Center, Piscataway, NJ, USA.

Interview

INTERVIEW: Dieter Kind

INTERVIEWER: Frederik Nebeker

DATE: 29th August, 1994

PLACE: Braunschweig, Germany

Childhood and Wartime Germany

Nebeker:

Did your father do electrical engineering for the army?

Kind:

In some way, yes. He was a pioneer. He was in command of a company doing civil engineering work for the army in France and Russia. At the end of the war he was in Prague and was taken prisoner by the Americans, and the Americans then handed over these people to the Czechs. So he became a prisoner of the Czechs, and this lasted several years.

They kept him until 1948. Meanwhile, the family was scattered all over Germany, and finally we came together in Bavaria.

Nebeker:

So you remember the war years?

Kind:

Oh, sure. We lived in Reichenberg, Bohemia, where I was born.

Nebeker:

Was that very hard on your family?

Kind:

Well, my father and many relatives were soldiers but the bomb attacks were not very severe in our area, because the bombing took place more in the industrialized centers like Berlin. And Braunschweig, by the way, was one of the most damaged cities. Sixty percent was destroyed. This did not happen in the Sudetenland or Bohemia. But of course in 1945 we were pushed out and lost everything. That was a rather severe end.

Nebeker:

Yes. Did you have brothers and sisters?

Kind:

Two sisters.

Nebeker:

And you moved with your mother in 1945 or thereabouts?

Kind:

That is a rather complicated story. It would be too lengthy to tell it now. We didn't know whether my father was still alive or not, and we were thrown out of the house. We were given two hours' time, and each person was only allowed to take 20 kilograms with them. We packed some things, and we were taken into what one could call a concentration camp. But we were very, very lucky: after two days staying in the camp in a not very pleasant situation, we were driven through the town and then put into an open railway car in which goods were normally transported, and brought to the city of Zittau in Saxonia, which was 26 kilometers away. At about the end of that we were with a hundred thousand other banished people. You may have heard how Germany looked in these days.

Nebeker:

Yes.

Kind:

So, you asked, "How was the war for you?" The war was not as bad as for many other people who lost their homes or even their lives from the bombs, but the end was of course as bad as it could be.

Nebeker:

Did it interrupt your schooling a lot?

Kind:

Yes, of course. There was no school; everything was upside down.

Nebeker:

For how long?

Kind:

Oh, I was thrown out together with my mother and my sisters. The Czechs had normally selected various people according to age and state of health. The group that I went with was slated to work at the uranium mines at Joachimstal but it would be too lengthy to tell you how my sister managed to put me into the group of those who immediately were pushed out. We were happy to be rid of this immediate danger, and even though we lost everything, we were in some ways happy that we escaped.

Nebeker:

Yes.

Kind:

Not all did.

Education and Cold War Germany

Nebeker:

Was it clear to you from an early age that you would go into engineering?

Kind:

Yes. Even when the base, the possession of an electro-technical firm as the reason for such plans disappeared overnight completely, I still had in mind I would like to study electrical engineering. Then my mother, my sisters, and I stayed in a little village in the southern end of Saxony. Bohemia is surrounded by mountains that partly belong to the Czech Republic, and partly to Saxony.

Nebeker:

I see.

Kind:

The people spoke similar dialects. Well, they were German. We would have to look on the map to make it clear that the mountain area surrounding Bohemia was nearly 100 percent German. I hardly knew anyone in our town who was not German.

Nebeker:

So was it difficult to get to Bavaria, get to West Germany?

Kind:

Well, it's a long story. I went to Freiberg in Saxony for school then, and I made my abitur, which, you know, is the final exam in Germany. Then I went to Dresden and I had the name of a certain professor Martin Kersten. He was a physics professor, and I asked, "Could you give me a hint how I could manage to become a student in Dresden?" and he said, "Dear friend, there is no chance. Your father was an electrical engineer, and under that situation my recommendation is to go elsewhere, perhaps to Berlin. At the Technical University of Charlottenburg you may have a better chance." I mention Professor Kersten's name because he was one of my predecessors in this chair here. He was president of the Physikalisch-Technische Bundesanstalt number 10; I'm number 12. I met him again here after many years, and he remembered that one day in 1947 a young man came and said, "Could you help me to study in Dresden?" And he remembered that he was sorry that he had to tell me there was no chance.

Later, I went to Berlin and worked in some factories and somehow I managed to become a student at the Technical University. There was a commission to check applicants, and I had practically no chance even to become invited for an interview, so I said to the professor, "My father is somewhere in a prisoner of war camp. We lost everything. Give me the chance to have this interview. I know I have no chance to become a student." He gave me the chance. This was before the division of Berlin, and the person in this committee who made the decisions was obviously a communist politician. This was one of the very lucky circumstances in my life — she asked me whether I had heard anything about the Communist Manifesto by Karl Marx. You know, that's basic.

Nebeker:

Right.

Kind:

And that was my topic in the abitur. So I knew more than she did.

Nebeker:

To her you were a good communist.

Kind:

So I owe everything to Karl Marx, and I presented myself as a perfectly interested communist and this made the point indeed, no doubt. I know for sure that I was the youngest student at the whole Technical University, because when the lists came out with the year of birth, there was only one for the year 1929, and that was me.

Indeed, in those days you had to concentrate on the immediate problems of getting food and to do things which gave you hope for tomorrow, and I hardly know what material basis I had in mind when I started studying. I had no income, my father was away, my mother and my sisters were in a little village in the Soviet zone. But still, we were not so pessimistic as people appear now. It's very strange for someone of my generation to see how pessimistic people are these days, when they have such a very high level of comfort.

Nebeker:

Yes.

Kind:

Having these experiences made me free for life. I do not have any reason to complain, as far as personal income or material things are concerned. I really do not care very much about these things. I have my experiences and they are a treasure. In having lost much of what we would have liked to keep, still we were not desperate, not at all. Not at all. Sometimes angry, but there were quite good interrelations between people in those days. I remember when you went with the railway, there was very little chance to have a seat. We were packed standing like herrings for hours, and the train stopped for what time you don't know when, but it would move again, and I still remember discussions at night with people you never saw really, because it was dark, you see. We had the most profound talks in these days. These were in a certain sense very rich years of my life indeed, from 1945 to1948, during the blockade of Berlin.

Nebeker:

I see.

Kind:

I stayed in Berlin when it was supplied by the American and British planes.

Nebeker:

Right. Was it divided at that time?

Kind:

Yes.

Nebeker:

Did you get into the western part?

Kind:

Yes, I was lucky enough that the Technical University was in Charlottenburg, in West Berlin. So I automatically got in. Then when we heard that my father would be released, we tried to tell him, and he understood immediately that he should try to go to Bavaria, West Germany, where a friend of his was re-opening a factory. Finally, when the family was in Bavaria, we came together and since we were still alive we knew that everything could only get better. That was the reason for our optimistic attitude.

Nebeker:

Well, I can imagine going from the destruction of much of the country during the war to a booming economy must have been exciting.

Kind:

Yes.

Nebeker:

So you went then to the Technical University in Munich.

Nebeker:

Yes, after three semesters in Berlin, Charlottenburg, I went to Munich. It wasn't easy in these days for someone in West Berlin like me to get to West Germany. At Christmas 1948, I wanted to see my father in Bavaria for the first time in four years. I had the address of a farm where by night those met who wanted to go over the green border, as we called it. There was no wall in these days, but the Russians of course already had police or soldiers patrolling, and they arrested people. My mother and my sisters were twice arrested and put in prison for one or two days and then sent back to East Germany. Now, I had this address, and finally there was a group of people who waited until midnight and then said, "Okay, now we can make it. The patrol is far away; let us go now." I don't know how much I had to pay. It wasn't too much; I wouldn't have had much money. So it was more or less fair play, and it was a group of let's say twenty people, and with me there was a family from East Prussia — a grandfather, his daughter, and two little children. The father of the children died in the war or was still a prisoner. Anyhow, they had an enormous amount of luggage. I only had my rucksack. I wonder how they ever would have managed without my help. We couldn't carry all these bags, the stuff they had. Just go west, go west.

Nebeker:

Audio File

MP3 Audio
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So you walked through the night?

Kind:

Yes, through the night, and sometimes we had to lay on the ground, and be silent until someone said "Now, go ahead." It was very exciting, you see. Many, many people tell a similar story. That's not special. But what is special is the following. I entered a train in Hanover to Munich, where I hoped to see my father who was then released from prison. Again we were sitting very crowded in the car, and someone asked me, "Where are you going?" I said, "I am going to Munich," and then he said, "Well, now we are approaching Eichenberg. Then they will again be taking people out of the train." I said, "Putting people off the train? What do you mean?" He said, "Now we are passing over the border between the British and the American zone, and you need a special visa for the American zone." I said, "What special visa? I thought I was in the West." He answered, "Why, we have an American, a French, and a British zone, and here is the border between the British and the American. Don't you have the visa?" "No, no, I have no visa. I thought everything was done, that I can go on. Oh, what shall I do?"

The train had already started moving. I should have left the train before the border, walked ten kilometers, and then entered again. Then the man said, "I realized that the sign on the toilet is not working correctly. So, if you go to the toilet and close it, the sign will still indicate that it is free." So I did. This was the only room with some light, and the shadow of my body was reflecting on the non-transparent window of that little cabin. So I pressed my thumb on the switch. They entered and tried to open the door with their special key, but it was not possible for them to move it, because I pressed the handle. Then again they tried, and so I stood there in that little area and pressed and pressed, and then the train started moving again and after a while someone knocked. My friend said, "We are through. Come out again."

Nebeker:

My goodness.

Kind:

So in '49 I went to Munich, and I continued my studies there at the Technical University, and finished in '51.

Nebeker:

And this was electrical engineering?

Kind:

Electrical engineering.

Nebeker:

What did you plan to do? Was your father going back into business himself?

Kind:

Yes. He was very lucky that he finally got a job at the AEG in Frankfurt. My parents moved there and for a while I didn't know where to go in industry. Professor Hans Prinz, however, offered to let me work under his supervision for my Ph.D. in high voltage engineering. Of course, I accepted.

Ph.D. Thesis: The Equal Area Criterion

Nebeker:

I see. Can you tell me a little about your Ph.D. work, the research you did for that?

Kind:

Well, I worked in the field of breakdown of air. In those days it wasn't clear how the electric strength of gases, especially air that is the most important one, reacts on different shapes of impulse stress. So I made many experiments on the breakdown between various shapes of electrodes. Only oscilloscopes with cold cathode tubes were able to measure microsecond-duration events. With these oscilloscopes, you had to put the film into the vacuum tube, then make your measurements, and then you had to take the film out of the vacuum tube to develop it. After a while you saw what you had measured and you found out if everything was all right. Of course this was not as convenient as today where you have a screen in front of you, and it was long before the first sealed tubes with heated cathodes became available, where you just make a photograph from the screen.

Nebeker:

Right.

Kind:

Then you make your photograph, and it's much easier of course, or you have your storage screen and that's perfect, and you look at it, and when it's fine, then you make your photograph.

Nebeker:

Yes.

Kind:

So it was very tiring. Indeed, one day I was quite desperate after two years' time, and I sat down and said, "Well, forget about everything, make a little model, a simple model," and then I was very lucky that I started the model and made some calculations. I saw that the result of it could be expressed by a formula. It's so simple, and then I had to check my measurements with that formula. Astonishingly enough experiments confirmed the formula stating that a certain area in the voltage-time domain should be constant. I called it the formative area because it can be interpreted as a generalization of the formative time that is well introduced in physics.

Nebeker:

This is for breakdown discharge?

Kind:

Yes. And so if you have any type of voltage shape, you only need to make an integration and it tells you whether or not you would have to expect a breakdown. I went all through my measurements and I found that they were pretty well proving the criterion.

Nebeker:

This was theoretically derived?

Kind:

It was, yes. Let me see; I should have some writings. This is just a collection of papers, which refer to this law.

Nebeker:

What is that law? How is it usually referred to in English?

Kind:

Equal voltage-time area criterion.

Nebeker:

I see.

Kind:

Or just equal area criterion.

Nebeker:

Okay.

Kind:

If you are interested, I could give you a copy of one of these papers where this is described: "The generalized integration method for predicting impulse volt-time characteristics for nonstandard wave shapes." That is by scientists who worked in that field, and I think that is one of the best articles with many references. Sometimes more general assumptions about the exponent K are made, and it ends up by saying if K is equal to 1, then we have this simpler version of the equal area criterion.

Nebeker:

So this had a large influence on the field?

Kind:

Yes, in some way. After my thesis was nearly finished, I had a tough time when I found a reference to an article by Hagenguth, whom you certainly know by name. He was the chief electrical engineer of General Electric in Pittsfield, Massachusetts, where I met him much later. He had earned his Ph.D. in Munich long before, but he was American, and has made very substantial contributions to the high voltage field. He wrote that article, published in 1941, but I couldn't get it. I only had this reference. I was afraid that it could have been exactly my subject.

Nebeker:

In Munich you couldn't get hold of that?

Kind:

No. It was published during the war, you see, in 1941.

Nebeker:

Oh, I see.

Kind:

I couldn't find it in German libraries. Finally when I got it, I was so happy to see that his approach was very different. He only said that you shouldn't just take one curve; you needed the whole area of all possible dependencies of the breakdown voltage from time. He didn't make that law, you see, but still some people take from the title of Hagenguth's paper that he must have been before me. But it was completely different. So if you like I could make a copy for you?

Nebeker:

Yes, yes. I would be interested in that. I'd also like a list of your publications.

Kind:

Sure.

Nebeker:

I would appreciate that.

Kind:

You will get it. I just collected the papers where the equal area criterion is cited.

Nebeker:

Was this immediately noticed when you completed your dissertation?

Kind:

It took some years. I intentionally did not continue in the field because I wanted others to check the criterion independently. Another reason is that I then joined industry, and in industry you hardly have the chance to make basic investigations. But the breakthrough came when the sealed cathode tubes were used, when people could make such measurements much more easily.

Nebeker:

Then it was easy to verify.

Kind:

And they gathered information and could check it, you see. Of course it's not a strict law; it's just an approach — which is quite useful. It's not based on a solid physical theory.

Nebeker:

You're saying that it's an empirical law?

Kind:

I would say semi-empirical. I made a physical model and the model is very simple, saying that you need to establish a conducting path between the electrodes. This path is completed with a certain speed, and you integrate over the path, and when this is done over the whole distance then the breakdown occurs. The only question is how to make the relation between the speed of this bridging depending from the voltage, from the stress. My assumption was that the speed at any point is proportional to the difference between the actual instantaneous voltage and the static voltage where no breakdown would occur. So you need to lift the stress over a certain level, and then the discharge starts.

Nebeker:

So this was a simplified model that suggested this law, and it turned out to be very often close to the situation.

Kind:

Yes. It even was found quite useful for insulating gases, such as SF6, not only for air.

Kind:

The figures for this constant area were found to be very much varying with the heterogeneity of the electric field. If you have sharp edges you need much higher over-voltages, and that means the area becomes larger than in homogeneous fields where, after it starts, it goes very quickly. So this is much more thoroughly investigated by others than I could have done with my poor equipment in those days.

Improvement of Testing Apparatus

Nebeker:

Was the school in Munich behind the times in its experimental apparatus, or was it just that there wasn't better at that time?

Kind:

They were very poor, because everything was bombed, and we worked with rather old things, but we had the most advanced cathode ray oscilloscope. There were not better ones in the world than the one made by Trüb Täuber, a Swiss company. And even in America the electrical laboratories didn't have better means for measurement.

Nebeker:

I see.

Kind:

Such very fast events, and what is characteristic is that each test is unique. You cannot repeat it. It's a single event, and you have no chance to make it more visible by repetition, as you have in high frequency. You have one event and either you have it or you lose it. It is a problem, to have such fast recording possibilities for single shot events.

Nebeker:

I see. Just to digress a little bit, what is the story of the improvement of that instrumentation? You said that you later got the hot cathode ray tubes.

Kind:

Yes.

Nebeker:

When did that come?

Kind:

Again, there were already hot cathode ray tubes, but not for single events. For single events, oscilloscopes had to be developed by special firms. The Tektronix 507 was the first I remember which really could do it. And then Haefely made a special development, and also AEG. At home I would have certainly some records of this, but I would guess that it must have been around 1960 when the hot cathode sealed tubes exceeded the cold cathode tubes for these single shots.

Nebeker:

So then it became much easier to get these measurements.

Kind:

Yes. And now the development is that high-frequency commercial oscilloscopes with amplifiers or even digital recorders are fast enough, but we normally use them in a special cabin, to get rid of EMC problems, electromagnetic disturbances.

Nebeker:

I see. There are some fields where the advance has been very much determined by instrumentation; when a new instrument is available then progress is made. How true is that of this high voltage phenomena?

Kind:

I would say that this high speed, short time recording instrumentation was necessary for the development of modern systems. The investigation of breakdown phenomena in large air gaps under switching impulse stress is of importance for ultra high voltage transmission, and for the development of sulfur hexafluoride insulated systems. These are called GIS, for gas-insulated systems

Nebeker:

Right.

Kind:

In both cases the behavior under impulse strength is decisive for the functioning of the whole system, and this could not have been investigated without this instrumentation.

Messwandler-Bau & High Voltage Eqpt.

Nebeker:

I see. You then went to work for industry in 1957.

Kind:

Right.

Nebeker:

Can you tell me something about that?

Kind:

Yes. This was a private firm in Bamberg, Bavaria, specializing in the field of high-voltage measuring and testing apparatus. The owner and general manager was Dr. Friedrich Raupach, a very creative engineer.

Nebeker:

I see.

Kind:

The name of that company was Messwandler-Bau, or MWB. And Messwandler means instrument transformer for measurement of voltages and currents as they are on high voltage lines. This is a booklet issued at the thirty-five year jubilee of the company. I could give you this if you like.

Nebeker:

I appreciate that very much.

Kind:

Dr. Raupach died some years ago, and I must say that the whole company is now not as it was. It was sold by his son, and that's a very sad story. It's very disgusting and disappointing for me that the company, with which I worked five years very successfully, went down. I had a very good relationship with Dr. Raupach and he trusted me. I was more or less the scientific and technical director there. After I came to the University of Braunschweig here, I continued to have close contact with him. Many developments they made in high voltage testing equipment — which was the second branch besides the instrument transformers — have very much to do with that. It became one of the leading companies in the field. You find their products, at IREQ, the research institute of Hydro Quebec near Montreal. Or in France at the big high voltage institute, Les Renardieres near Fontainebleau of the Electricité de France. They were also equipped with test transformers that to some extent were based on my developments. So some of my, let's say, technical children passed away with the fate of that company.

Nebeker:

Thank you very much. We try to collect company histories, and that's very interesting to us. In your years there, how long was it that you worked there?

Kind:

About five years.

Nebeker:

You were designing transformers some of the time?

Kind:

Yes. Designing test transformers and other equipment for high voltage test technique.

Nebeker:

The test instruments.

Kind:

High voltage testing. You see, a test transformer is very similar to an instrument transformer. With the test transformer you step up a low voltage to a very high voltage for test purposes. With instrument transformers you apply a very high voltage and the output is a low voltage for measuring purposes. Of course the test transformer has still higher rated power, but the design principle is closer to an instrument transformer than to a power transformer. A power transformer is a three-phase unit and must have continuous rating, while the test transformer has normally only short duty, because the test doesn't last forever like power transmission. They are very much of the same principle, so I made designs and investigations to find out what physical conditions have to be obeyed to have a safe operation.

Nebeker:

And these were very successful designs, some of them?

Kind:

Oh yes, I would say yes.

Nebeker:

Did you patent some of these?

Kind:

Quite a few, yes.

Business and Engineering

Nebeker:

What else did you do in your years there?

Kind:

Well, if you work close to the top in a company of 500 people and you have a very good relation with the owner, then you have to do a lot of things starting from leading people, or from making acquisitions of material. I went to various parts of the world, the United States and so on. You know the big Niagara Falls hydro power station with its huge instrument transformer banks, they were all supplied by Messwandler-Bau, and this was a rather risky order. If something went wrong, the company would go bankrupt at once, you see. The company was too small to handle a million dollar order. But everything went well. And you hardly could find an insurance company to keep you safe. It was a very active company. It was sometimes very exciting, and I did not always sleep well. But I was really a full industry engineer. I had no plans of going to a university. I was happy.

Nebeker:

Would you have preferred to not have these business aspects of the job and just do design?

Kind:

No, no.

Nebeker:

You enjoyed doing that?

Kind:

In my function here as the president of a big national institute, the experiences which I collected at that time are most important. In industry you learn what responsibility means, how you have to talk to people with very different kinds of education and backgrounds and how you have to behave to generate confidence in what you say. You have to listen to whether they do not agree with you, and then bring them to speak out when they don't agree; not just to say, "Okay, we'll make it," and thinking, "We will see what the outcome is," so to learn how to be in contact with people.

Nebeker:

And you enjoyed that very much.

Kind:

Oh yes, very much.

Nebeker:

You didn't long to return to a purely research setting?

Kind:

The question didn't occur to me until when it came.

Braunschweig Technical University

Nebeker:

And how did that happen?

Kind:

Yes. I had very high esteem for professors in those days. I was at the Hanover Fair representing my company, and I got a telephone call from Professor Erwin Marx, the famous inventor of the impulse generator and a man whose name is well known in high voltage engineering all over the world. He asked if I could come to see him in Braunschweig. Braunschweig was the only technical university in Germany where I never been before, you see. He said, "Yes, I would like to speak with you. You may know that I have to resign because of my age, and I would like to talk to you about that." I really was very excited. I came and saw him and I said, "Professor Marx, this must be a mistake. Thank you very much, but this must be a mistake." I thought he didn't know how young I was, but he said, "Well, you are 32 now. This is about the same age I was when I came to take this chair." Then, well, three-quarters of a year later I was here. We just had bought a house in Bamberg where the company was, and when the family moved in we knew that it was only for a few months. And then I started here, and I was very happy as a university professor and I had many very good students and Ph.D. coworkers.

Nebeker:

I take it that that institute of high voltage technique was already very good.

Kind:

Yes, but it was rather out of date with its equipment. It was still the postwar time, you see? It had very old buildings and everything crowded. Professor Marx didn't take much care on modern shape and so he was the great old man. But we had a very good relationship with each other. I never applied for his succession, I wouldn't have thought of that, you see. They asked me, "Will you be ready if we call?" And then I said, "Okay." I made negotiations in Hanover on the salary and such things, and then I said, "Yes, if you think I could manage it, I will try it." Of course my company wasn't happy, but Dr. Raupach understood that it was also a chance for him to have good contact with a research institute. All my students certainly had much profit from that relationship — and also the company.

Nebeker:

So some students of yours came from the company?

Kind:

Went to the company.

Nebeker:

Went to the company. And then had leading posts and positions at the company. Okay. I thought there might have been some cases of people from the company going to the institute for further training.

Kind:

No, that way doesn't work in Germany. It's a pity.

Publications while Working for Industry

Nebeker:

I see that you did have some publications in your years with the company.

Kind:

Yes, but the condition for publication is not as easy as if you work with a research institute.

Nebeker:

Sure. And I would imagine also that the company doesn't put a premium on it.

Kind:

But when you manufacture equipment needed for research experiments, then you need close contact with scientists who want to work with these. And so you care that leading people in your company have good reputations with scientists. Then it's not just like something that you sell and then that's it, but you need to talk with each other.

Nebeker:

I see.

Kind:

And so it wasn't so far from science.

Teaching and Research

Nebeker:

And how did you like going to the university?

Kind:

Well, at first I was very doubtful whether I would have the necessary and the expected scientific basis. As a student, I had no income and during the holidays I had to earn money to keep things going over the semester and so on. So I had not such a thorough study as people have today and it was much shorter because I had to try to earn money. So I had to work hard to complete my scientific knowledge when I became a professor, and many things that I had to teach were new for me some months before.

Nebeker:

Not the first time professors have learned material as they taught it.

Kind:

Exactly. Obviously that is not a bad basis. You make things much more simple and understandable for the students. So they liked my lectures and I have quite a few letters or statements saying that their decisions about pursuing professional careers went back to what they heard in my lectures. Of course that is a nice thing to have.

Nebeker:

Yes. I see that over the years you have had an incredible number, sixty theses done under you?

Kind:

Sixty-four or sixty-five and in various fields.

Nebeker:

Is that right?

Kind:

Yes.

Nebeker:

So you must have done a lot of work with research students.

Kind:

I still do it, and it's my great pleasure, and for my function here it's important that at least in one isolated field I really have connection down to the very ground. I like it and it keeps me active, although it's sometimes not so easy.

Nebeker:

Tell me about the Institute for High Voltage Technique in the years you have directed it. How did that go?

Kind:

I think very well. We concentrated on certain research fields, on a special question of insulation, partial discharges, and we made an industrial achievement, the development of circuit breakers for high voltage DC transmission. That is a very tricky plasma arc procedure and it was because of our developments that three competitors, AEG, Siemens, and ASEA, made a combined joint venture with us for the further development of that circuit breaker. Also there were two more lines, one with General Electric and another with Hughes Aircraft. I really think that the European concept that started in Braunschweig was felt to be the most economic one, and certainly this was one of the achievements we made. We had very good students, and quite a few of them are professors now or in leading positions in industry somewhere.

Nebeker:

So the DC circuit breaker was one important development.

Kind:

For high voltage direct current, yes.

Nebeker:

What other areas of work was the institute known for?

Kind:

The behavior of solid dielectric under impulse stress or with partial discharges, those little discharges which are considered dangerous for the long-term behavior of insulation.

Physics and High Voltage Engineering

Nebeker:

Are there some physics institutes somewhere that are doing work that is relevant to this kind of research?

Kind:

Yes. High voltage engineering is very close to physics. And if I am interested in the behavior of structures insulated by air under a high voltage stress, then I need to know the actual state of gas discharge, of plasma physics if you like. And so many famous physicists, like Paschen, Townsend, or Raether developed the fundamentals for engineering. If I consider my job here as an engineer experienced in the high voltage field, I necessarily must have a very wide view. If you develop a high-precision measuring instrument or what have you, it's quite the same. It doesn't matter why it fails, whether it becomes too hot or it has insufficient mechanical or electrical strength or the design is wrong so that humidity gets in, and so on. As an engineer in design, especially in high voltage, you must really have a very wide background also in thermal questions, in mechanics, vibration, acoustic, and so on.

Nebeker:

Yes.

Kind:

Reaction of penetration of humidity and oxygen from the air into insulating liquid, all such things which you come across in industry.

Nebeker:

Right. Well, that's a very good characterization of the difference I think between engineering research and physics research.

Kind:

Yes.

Nebeker:

My question is really, are there current areas of research in physics that are important to people doing this kind of engineering research? Maybe some of the plasma physics work, I don't know.

Kind:

In plasma physics, certainly, and of course in solid-state physics, so the development of transistors and thyristors and all these microelectronics elements. When I worked in the HVDC, high voltage direct current field, connected with the breakers, they were still working with mercury arc converters, and but slowly solid-state elements were introduced. Actually today no one ever thinks of using a mercury rectifier.

Erwin Marx and High Voltage DC

By the way, the very first HVDC experimental transmission was set up by Professor Marx here in Braunschweig.

Nebeker:

Is that right?

Kind:

Yes, during the war.

Nebeker:

Oh.

Kind:

He was at the same time a good politician. He managed somehow to convince the high military people that if we would be able, "we" means Germany, to realize HVDC transmission, we could put all the high voltage lines and cable underground and then we could bomb the high voltage lines of the enemies and they could not take revenge, because everything was buried. They worked until the end of the war on this research.

Nebeker:

Now, was that purely a rationale to be allowed to continue his research?

Kind:

Yes. He did well convincing them of it.

Nebeker:

Right.

Kind:

So it's something like SDI these days.

Nebeker:

He didn't conceive of high voltage DC as a means of making power transmission bomb-proof; that wasn't his real —

Kind:

That was the argument.

Nebeker:

That was his argument, but that wasn't his real interest?

Kind:

No, no, no.

Nebeker:

Did he think that it really was preferable?

Kind:

Indeed you could make a long, undersea cable with DC what you never could do with AC. So the connection between England and France is DC, and between Sweden and Denmark is DC, because you do not have the polarization losses in a DC cable.

Nebeker:

I see.

Kind:

Only the conduction losses, and they are some orders of magnitude smaller. With AC, such a cable has a very high capacitance and you must get the capacitive current, which you have to generate. So the underground cable over long distance is only feasible in DC and not in AC.

Nebeker:

Were there other people at the time talking about high voltage DC during the war?

Kind:

Oh yes. Another group in Germany as well, Siemens and AEG together. The first commercial HVDC was the link between Sweden and the Island of Gotland, and this was established by Dr. Uhlmann, who was a Ph.D. student of Marx.

Nebeker:

Is that right?

Kind:

Yes. He was married to a Jewish lady. We knew them very well, and they still had a friendly relationship with Marx. They had to emigrate to Sweden, but the knowledge with which he started went back to his time with Professor Marx. By the way, he was the first to get the A. Uno Lamm Award of the IEEE I think.

Nebeker:

Right.

Kind:

That is Erich Uhlmann. He died three years ago. So Braunschweig is the source of many important engineers in the field.

Nebeker:

That's very interesting.

Kind:

There was also Dr. Debus, who was the right hand of Wernher von Braun, and was also a high voltage engineer

Nebeker:

Where those scientists interrogated by the allied military?

Kind:

Not Marx. Many others, but not Marx.

Student Protests

Nebeker:

Is there anything else that you care to comment on your 13 years or so as professor at the Technical University?

Kind:

Well, these were the years of the Berkeley protests. We call it the '68 years, the students' revolution and protest. In those days I still was one of the youngest professors, and I always had to stand upright and to represent the position of professors you see, and so I had a tough time. I was the Dekan, the head of the faculty, and a member of various reform committees, and so when I left university and came to PTB [Physikalisch-Technisch Bundesanstalt] here I had one meter of papers related to those issues. It's all forgotten stuff now.

Nebeker:

But that took a lot of your time in those days.

Kind:

Yes. My first reaction was that it was a waste of time but I must confess if the same situation would occur again I would do the same. If you are engaged in the student work and the university you do not let things just go downward. You try to do what you feel you should do.

Physikalische-Technishe Bundestalt

Nebeker:

I don't know anything at all about the situation here, but to have someone on the faculty willing to make a real effort might have been important. And then in 1975 you became president of the Physikalische-Technishe Bundestalt, the PTB.

Kind:

This was again something that I never had thought of. You may know a bit about the PTB. This is a very traditional institution, and the first president was Herman von Helmholtz, the famous scientist.

Nebeker:

You know, I have a bust of von Helmhotz in my office.

Kind:

Have you?

Nebeker:

Yes.

Kind:

By the way, on the 8th of September, ten days from now, we will celebrate the 100th anniversary of his death in Berlin, and this will be a three day event which I am responsible for because the presidency of the PTR, the Physikalisch-Technische Reichsanstalt was his last position. So we felt it was our duty to organize this celebration. We even have a U.S. historian, Professor David Cahan, who wrote about the history of PTR. I could give you some English literature about this institute here. So it's a very traditional institute and a big one, two thousand people now, and it was the first institute of its kind worldwide.

Nebeker:

When was it founded?

Kind:

1887, and it was pushed by Werner von Siemens, who finally made a donation of a very suitable and big site in Charlottenburg with the obligation to start this institute. It was for the first time worldwide that a national laboratory, as you would call it, a national institute, as we call it now, was established. Before that time there were eminent scientists like Newton and Maxwell and Gauss and Lavoisier and so on, or even Helmholtz. But they were just one man, and they had some technicians or students around them, but those were one-man institutions that ended when this man died or retired, you see? This was the first time that a state established a national laboratory. Soon the British and the Americans tried to follow up, but it took them until 1900 or 1901 to start the National Physical Laboratory in Teddington and the National Bureau of Standards in Washington. So it was very clear they were shaped after the model of the PTR.

Nebeker:

Yes.

Kind:

And for this reason we still have very good relations with other national institutes, because we have more or less the same history. When I was asked to take this job I knew that others had been asked before, but did not accept for various reasons, and I was still not very old, 46. As in other cases, I asked if it was thought I would be able to manage this, to take this giant task. When I saw no reason why I shouldn't be able to do it, then I felt some obligation to try it. So I did, and I think it worked.

Nebeker:

How large was it at the time?

Kind:

Well, about 1500 employees, maybe. It grew a bit. Meanwhile we had been made responsible for the disposal of nuclear waste. This was an additional task. This went out in 1989, but then came the German unification, an event we hardly had dared to hope that it ever would happen. We took over a few hundred people from the corresponding East German metrology institute.

Nebeker:

I see. What were the main challenges when you started your work here?

Kind:

The basic task is measurement, metrology, the science of measurement, and this is a horizontal discipline that occurs in every field of physics and technology — in acoustics and mechanics and electricity and optics and thermodynamics, in ionizing radiation, what have you. So you need a very wide horizon to be able to at least follow the principle of what these specialists do. That's what I mentioned before; having been educated and having worked as an engineer, I think it was a good education for this type of wide-angle responsibility.

Reception by Physicists

Nebeker:

That you were the first engineer to oversee this institute.

Kind:

Yes. Of course, some were very skeptical. First, they thought I was too young: "If he stays until retirement it could be disastrous." And then, how could an engineer dare to take up the flag of someone like Helmholtz or Nernst, or other people in that tradition? It was easier for me because I had lived in Braunschweig before, so I did not have to change my private situation. I didn't even have to move. My children got to continue going to their school, to keep their friends. And of course the challenge, you asked about the challenge. It's a federal institute. You have to make it; you have to represent it against the government, against the ministry of economy to which it belongs. When we became responsible for the disposal of nuclear waste I even had to work close to politics and had to defend what we were doing, all these projects which were started by PTB.

Nebeker:

So a large part of your job was not entirely political, but the public side of —

Kind:

At least with a feeling for politics. Of course no party politics. But if you do not understand how the public feels, then you could easily create hostile feelings. We need and have very good contact with industry because industry needs us. We are providing their basis, and then with universities, with science. So it's everything that comes together.

Nebeker:

Is it a large part of your job to work for the political support of PTB always?

Kind:

Not personally, no.

Nebeker:

So you have the support of industry and universities and —

Kind:

Yes.

Nebeker:

You don't have to lobby or —

Kind:

No, not really. Part of our task is so clear to everybody. If I am asked by someone why PTB exists at all, I say, "How do you know that you get as many liters of gas into your car as you are supposed to pay for?" They say, "I have no idea." And I say, "We take care of it, because you can't do it." Or if you are at the doctor and someone is doing a measurement, who takes care that the measurements that are being done are correct? The doctor believes in his instrumentation, that's all. But he doesn't know.

Nebeker:

Right. It's absolutely fundamental to science and industry, but nevertheless I think especially these days people very often have to convince the politicians that such things are crucial.

Kind:

I fully agree with you.