Interview: Harold Kaufman
1991 Albert Nerken Award Recipient
Interviewed by Jerome J. Cuomo, 1991
CUOMO: My name is Jerome J. Cuomo, known to most of you as Jerry. I'm with the IBM Research Corporation at Yorktown Heights, New York. It is my great honor and privilege to introduce to you today Harold Kaufman, who is the eighth recipient of the Nerken Award, which is given by the American Vacuum Society. I've known Harold for a good 17 years, and we've been close friends ever since our first meeting.
The citation for the Albert Nerken Award, states, "For the invention of the electron-bombardment broad-beam ion source, and extending its use in thin film applications."
Now as you and I both know, that covers pretty much your career in terms of where you come from and what we'd like to know about and the work and who you are. In the early days it was Harold Kaufman, and then it became Professor Kaufman, now it's Harold Kaufman or Dr. Kaufman. That sort of also tells us a little bit about your career. Why don't you tell us a little bit about how you got involved in this ion beam business, what the environment was like, and how you came to work with this source that has become known world-wide as the Kaufman source.
KAUFMAN: Well, I got started with the Kaufman source by working at the Lewis Research Center, back when it was NACA, National Advisory Committee for Aeronautics, and working on turbo jets. Then we became NASA; that was the nucleus of NASA in 1958. I started working on electric space propulsion. The important thing here is it was a practical application, applied research, propulsion in space that we were working on - not ion sources as an abstract physics project or something to study from just a knowledge viewpoint. The important part of this study was that we were looking at how to propel things in space, which meant lots of ions at low energy, which is basically different from everything done before. Before, they always looked at it as "how much energy? Get more energy, more energy, not less."
So it was a practical problem that had never been asked before. And because it had never been asked before, some of the answers were laying around, ready to grasp, compared to problems in turbo jets, where I'd worked on some things there that unfortunately had been worked on for 20 years, and all the easy problems were done. But in the ion propulsion field, why, the easy problems weren't all yet done.
CUOMO: What was some of the environment that you were exposed to when you were involved in the invention of these multi-pole, multi-aperture ion thrusters?
KAUFMAN: I was given the job of looking at the duoplasmatron to see if it would work for propulsion. I sat down and studied it a while and it didn't look right. The longer I studied it, the more it looked like it had serious current problems. You couldn't get enough current at low enough voltage. Then I redefined the project. I worked for a management that was lenient enough that they didn't insist that I keep following the same path, and they let me go into a new path, which was to make it a "rubber device" - stretch it around until it looked like it was something that would work better.
CUOMO: I am going to take off on this for a moment, this "lenient management". What does that mean?
KAUFMAN: Well, I think that there's several kinds of lenient management. Back then, this was a government laboratory. We weren't pushed to meet some tough schedule, and hence have someone looking over my shoulder and making sure I was doing exactly what I was supposed to be doing! It was lenient in that way. That type of leniency still exists in universities and government laboratories, for the most part.
CUOMO: So, apparently you had a little bit of freedom.
KAUFMAN: Yes. Now, there's a different kind of freedom that's needed today, though. That different type is that the knowledge base is changing so rapidly that the boss can't keep up with it all anymore. He has to have the people under him aware of the changes and following the changes. You don't do that by just having people follow orders.
CUOMO: So under this lenient management, what did you end up doing?
KAUFMAN: I ended up spending close to a year studying plasma physics and how to achieve high currents at low energy. As you know, why, the end product, it sounds rather prosaic now that, instead of having the ions come out of a single aperture, you can get more current at the same voltage by having multi-apertures extracting ions from the same discharge.
CUOMO: Obviously there's some motive for a NASA scientist to be involved in this type of project. What was the motive?
KAUFMAN: Space propulsion, more efficient space propulsion, You shoot a certain amount of mass out of a rocket, you can get more propulsion out of it if you shoot it faster. You can get a certain velocity by burning oxygen and hydrogen or some other energetic combination, but you can get even more velocity if you accelerate particles with electrical energy. That means that, in the present time, you can have a communication satellite with chemical rockets holding it in place against little perturbations for 5, 6, 7 years. But if you put electric propulsion on it, you can have it for 10, 15, or 20 years. The same satellite holding position without running out of propellant.
CUOMO: If I can interrupt. About the time that you started working on the multi-pole source or multi-aperture source, you were involved in looking for a more efficient way to do things with ions for propulsion.
KAUFMAN: For propulsion.
CUOMO: With that, can you tell us a little bit about the surroundings of the patent and what that patent meant?
KAUFMAN: Well, it didn't mean a great deal, back then. The government believed that it should keep track of all patents and any - for example, if a contract was let to a contractor, why if a patent came up, the patent became the government's property, fully. In fact, you had to sign over the rights to patents ahead of time if it was necessary for the work. So, not surprisingly, patents didn't come around very often. They weren't invented under that situation where there was only a penalty. So there was a patent, but I'm not aware of any real practical use of that patent.
CUOMO: Why don't you give us a timeline?
KAUFMAN: This took place back in 1960.
CUOMO: Already in 1960! What happened with the ion source from 1960 to, let's say up to about 1970?
KAUFMAN: During that time, there was a major effort at NASA Lewis, and under some contractors for NASA. We made what I believe is the first thorough investigation of ion sources, looking at all aspects of it - how you accelerate the ions, how you generate the ions, how you get more efficient ionization, how you get more efficient acceleration, how you get lifetimes of thousands of hours of the source. All that, and there was probably 200 professional man-years put into broad-beam ion sources during that period. There was a tremendous body of information that was worked on and developed.
CUOMO: I think the time that you're talking about so far had to do with space application. Now let's start to think about how did this get into ground-based applications, as we like to call it.
KAUFMAN: Hugh Garvin, at Hughes Research, was one of the first. Maybe you can think of a few more that started to use ion beams for moving material around, micro-machining. I had nothing to do with that. But I did have the benefit of having ten years prior experience before it began to be used in ground applications.
CUOMO: I think micro-machining has graduated to what they call micro-milling.
KAUFMAN: Yes.
CUOMO: Hugh Garvin was one of the early users. Who else was involved?
KAUFMAN: Well, the papers began to be published about 1970. Who was... Christian...?
CUOMO: Weissmantel ?
KAUFMAN: Weissmantel, he was another one. I suspect you can give those names better than I can, Jerry.
KAUFMAN: I think what we're looking for is how did you start to see space applications start to migrate towards the ground-based applications?
KAUFMAN: Oh. One person did some experiments, and some other person did more experiments. The first time I ignored it, and the second time, well, it might be interesting some day. By the time five or six people had done very interesting work using that source, why, I began to realize there might be something there. It was a gradual process, and, like probably all of my best work, was pushed on me by someone from the outside. Like, oh, someone more recently recommended that I go to work on gridless ion sources. I didn't really see the point of it. But then later on someone by the name of Ian Seddon asked me the same things and it began to make sense, finally. That first person, naturally, didn't get credit for this.
CUOMO: Who was that?
KAUFMAN: You, Jerry!
CUOMO: Oh, I see [laughs].
KAUFMAN: So, these applications are all things from other people. Sometimes, you just have to be bright enough to recognize something after you're hit over the head with it three or four or five times.
CUOMO: At one point, you left NASA. That was after how many years?
KAUFMAN: Twenty-three years.
CUOMO: What was the position you left?
KAUFMAN: I was Assistant Division Chief of a division of 125 professionals.
CUOMO: With all that background and all that experience, what did you end up doing with it.
KAUFMAN: Well, I went back and did work myself as a professor at the university.
CUOMO: Which one was that?
KAUFMAN: Colorado State University. I am proud that after being a manager for 15 years, I was still competent enough to go back and do work myself. That's not always true. I figure the time constant for decay of competency is about five years for most people - present company excepted, of course!
CUOMO: I guess around that time is right when I met you at the Colorado State University.
KAUFMAN: I was a professor in both Physics and Mechanical Engineering departments, teaching courses in both departments.
CUOMO: At this point, I'd like to mention that that's when I guess I came onto the scene. Jim Harper and I were on a tour of ion beam people and companies in the US and one day I went into this laboratory at Colorado State University and saw a huge, huge vacuum chamber and saw this also very large man standing in front of this open door. I was introduced to you then. That's, I guess, when I met you the first time. From that time, I started to understand the author of the multi-polar, multi-aperture source and what you did. He was only concerned about space applications at the time. It was his predominant interest. We sort of worked together for a while. But actually I guess our first interaction is that we were looking towards your knowledge. But why don't you tell us a little bit from your perspective how the interaction started and how the different sources came about.
KAUFMAN: Well, Jerry, of course, is very skillful at detecting abilities in other people that the other people sometimes missed themselves. This is one of his outstanding characteristics.
He questioned me about ion sources for quite a while. Then, sure enough, a month or two later, he came back and he had this wonderful theory of "smart" ions. Don't worry about "dumb" ions and plasma! Get "smart" ions that know which direction they're going, which energy they have, and you can do things that you can't do with some ions that just go in all directions and don't have any real organization to them. So "smart" ions, after you explained "smart" ions to me enough, I realized that that was what I had been talking about. I just didn't know it!
CUOMO: Can you tell us about some of the ion sources that you developed and of their potential use.
KAUFMAN: The first ion source was just a single type of source used for all purposes. What we've ended up doing is just multiplying the types of sources and the specific designs for all sorts of applications. But if you remember, we worked on a single grid source, I think, the first for industrial applications to get very low energy ions. We looked at dished graphite grids, which was a marvel of fabrication.
CUOMO: Is that one still working?
KAUFMAN: Definitely. That was the one that was on the cover of the May, 1980 issue of Physics Today. You pushed very hard to get me into gridless sources. I'm sorry that it took so long for me to recognize the wisdom of your direction. The End-Hall has come along now and provides at least amperes of ions at low energies up to 50-150 eV. I think that the most interesting development for me has been the property modification and the way we've changed sources to get those. But the first application was just removal of metal or material, milling, as you were saying - thinking of it as a machine-shop analog. Then we went to deposition, where you could do things like deposit tungsten on top of paper, or you could make an alloy of tin and tungsten, things you couldn't possibly melt and mix together. Some of the more recent ones where we've taken and modified a property; to make better hardness and we've improved the density and obtained condensation at temperatures below normal material condensation. Then, I think some of the more interesting ones are metastable states. Diamonds sort of puzzled me, but that was supposed to be a high temperature, very high pressure thing, and here we made them in vacuum tubes! We made some metastable oxides of copper and nitrides of Zr and Hf. All of those things have pushed us more and more towards high currents at a low energy. The closer we can define the energy and the lower the energy, the more important it seems to be. The End-Hall is very useful. I think that there are more developments needed in that direction.
CUOMO: While you were at the university, there were many people involved. Maybe you could tell us a little bit about some of those that were involved.
KAUFMAN: A couple of students that I had, one was Steve Rossnagel. He worked for you after leaving the university. I understand he received the Peter Mark Award. He's presently still working in IBM Research.
CUOMO: On the Director's staff.
KAUFMAN: Steve Robinson was another graduate student. He's now my colleague in business, in Front Range Research.
CUOMO: Tell me a little bit about working with him.
KAUFMAN: Well, I guess a typical example was that when we were first working together, we ran across an equation that I wrote in a report for NASA, an equation that was the integral of magnetic field over distance and stating that the depth an electron could go into a varying magnetic field was determined by that equation. He said, "Well, how did you get it?" I said, "I didn't get it. I just figured out that's the way it ought to be." He was very upset that I would put an equation in a paper without deriving it. He then spent about a month deriving it, part-time at home. He finally, proudly, brought it in. Well, it was the way I expected. He tried to keep track of my mathematics to make sure that I don't go off the deep end and do something wrong! He once told me that a colleague of mine at NASA Lewis had told him that I was pretty good at physical understanding, but you had to watch me mathematically!
CUOMO: What has been the most rewarding thing while you have been at the university?
KAUFMAN: Well, I think the collegial relationships that we developed have to be the most important and the most valuable.
CUOMO: I thought you would say some of those meetings that you had at your house with all the students!
KAUFMAN: You learn about food and graduate students. You don't want to put out too much, because, however much you put out, the graduate students will always eat all you have! I think that one requirement for a graduate student is that they must be able to eat enough at one of those parties to survive for a week!
CUOMO: It seemed that way. Harold, you've had a great career at NASA and then another career at Colorado State University. Actually, now you are an emeritus professor at Colorado State University. What are you doing? What have you been doing since then?
KAUFMAN: I've been doing research and development on plasma, low energy plasma, ion sources. This sounds very crass, and a lot of people talk about pure research. I think that what they often mean is that it's completely devoid of practical application. That makes it pure somehow. But the beauty of this is that I don't have to write long proposals for the government. Sometimes, with a half-hour discussion, we can then go ahead with a $100,000 or $200,000 dollar project. And I still enjoy the science. It's all the boilerplate and the paperwork that often goes with it that I think turns a lot of people off as they grow older. So I still enjoy it, very much.
CUOMO: And you have an active business enterprise.
KAUFMAN: Our business is called Front Range Research.
CUOMO: I remember I stood at the foot of the mountains in Fort Collins. So that's why it's called Front Range.
KAUFMAN: Yes. Front range of the mountains.
CUOMO: Now that you've been involved with all of these things, is there anything else-- Actually, there are a couple of things that I have to select here. Here's something I would like to bring up about the Awards Ceremony last night. Everybody had an opportunity to say something about how they got where they are and thank people in their lives. Is there someone that you know about that you would like to thank in particular?
KAUFMAN: Yes. But let me say something else first. When I left the NASA Research Center, I had a stack of 8 x 10 photographs of equipment. The stack was about a foot high, and it was all the projects I'd worked on, pictures of different things. You accumulate quite a bit in 23 years! And I realized that I didn't want to keep them all. I looked through and I sorted out the ones I wanted to keep, and I kept a stack about one-inch high and threw away the rest, most of them. Then I looked at them, and I realized what I had done. Mixed in these photographs, we had people to show sizes of things and to point out some feature; the people were incidental, compared to the machines. The machines were the important things. But the photographs that I kept were the ones with the people in them! It became the lasting value. There are mental photographs of people that again have the lasting value. And if I go through them alphabetically so I don't leave any illusion of precedence, the people I'd say in my mental photographs of the work I've done since them: Jerry Cuomo, Jim Harper, Bill Mickelson, Steve Robinson, Steve Rossnagel. And of course my wife, Elinor.
CUOMO: I was at the Awards Ceremony last night, and everybody has the same need and proper acknowledgement of the people who helped them.
KAUFMAN: We have some illusion, I think, of being individuals in this country. I think, at the other end, the Japanese have an illusion of being a group. It may be somewhere in the middle is what's important. As I commented, I seem to get an idea after it's fed into my head three or four times. A lot of people don't remember the previous mention. They think it's, "Oh! I got this great idea all by myself." They don't realize that it comes from interaction. But we don't operate in a vacuum and we don't operate as particularly isolated individuals. It's the interaction of people that matters. I think that's important.
CUOMO: [Laughs] I lived in your house while we were at Colorado and I know you may not be an easy person to be with, or so Elinor told me on the phone!
KAUFMAN: Well, I think there's a degree of playfulness in all of us, that being a successful researcher also means that you don't have to grow up.! So you keep playing with these toys far beyond the time when other people have to buckle down and do things they don't want to do. We get to play and have fun. Then, other people have to sometimes clean up the messes after us so we can have the fun.
CUOMO: Where do you see things going?
KAUFMAN: The crucial area, I think, is 500 eV and less. We're moving much more towards that. You can do just about everything you want to do with ion beams at 500 eV or less. We're finding more and more special applications where the lower the energy, the better. For many property modifications, 300 eV or less works fine. You said a while back, 100 eV or less for diamonds, and then you keep saying lower and lower. I'm sure that there's a lot of interactions, if we could get even lower, and nearer particular energy levels, but I don't think we'll ever get to the level of bond energies between atoms. So I think the need for production capability is high currents always. But lower and lower energies with better definition of energy, better knowledge base, and that's presumably going to mean gridless sources since grids just don't work very well at low energy.
CUOMO: Is there anything else I missed?
KAUFMAN: I hope that some day I'll have a series of patent accomplishments that approach yours. As I remember, you have more patents than anyone else in IBM, and I don't mean in IBM, Yorktown or IBM, USA; I mean in IBM. I only have 23.
CUOMO: Harold, I really would like to congratulate you on your award.
KAUFMAN: Thank you, Jerry.