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Oral History Transcript — Dr. Noah Hershkowitz

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Interview with Dr. Noah Hershkowitz
By Gary L. Cameron
At the 61st Annual Gaseous Electronics Conference (GEC) in Dallas, Texas
October 14, 2008

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Noah Hershkowitz; October 14, 2008

ABSTRACT: In the interview Noah Hershkowitz describes when he first attended a Gaseous Electronics Conference (GEC) in 1981 or 1982; was the long time editor of Plasma Sources Science and Technology, and he discusses the overlap between people involved in that journal and the GEC, and he is especially good on the international aspects of the field and future applications. Throughout he mentions Bill Graham, Peter Ventzek, Will Allis, Art Phelps, Mark Kushner, Richard Anderson, Dan Schram, Jim Willard, Alan Garscadden, Leanne Pitchford, Mike Lieberman, Mel Turner, and others.

Transcript

Hershkowitz:

Iím Noah Hershkowitz. My official title is Irving Langelier Professor of Engineering Physics at the University of Wisconsin. I do experimental plasma physics. Iíve been doing experimental plasma physics since 1971.

Cameron:

The main thing is your experiences with the GEC, any pertinent background information.

Hershkowitz:

I first discovered the GEC in probably 1981, maybe 1982. I had been a professor of physics at the University of Iowa, and then I used to go to the American Physical Society meeting. I moved to Madison. I was in an engineering department, then I changed my attention a bit and started looking broader. There I was doing mostly fusion related stuff, but I had been doing basic plasma physics for many years before that, so I continued with that. I started to do basic plasma physics in í71. My real connection I think is the atomic community got to be pretty strong after I started the Journal of Plasma Sources Science and Technology, and that was started 17 or 18 years ago I actually started doing that. I was sent a questioner from the Institute of Physics publishers, a British version of the American Institute of Physics, and they had questions about a journal that they were thinking about starting that had to do with plasma applications of one sort or another, and they asked questions about what people thought it should include and shouldnít include. I wrote back saying what it should include, and they wrote me back a letter saying would I be interested in being the editor. So we started it, and I did that up until last year. This is the first year I havenít done it. My vision of the journal that was needed was a journal that had together all the information about plasma sources and different kinds of ways of making plasma, and coping plasmas and diagnosing plasmas and modeling the plasmas, that were non-fusion related. There seemed to be quite a bit of literature on the fusion plasmas, but there didnít seem to be too much literature on the non-fusion plasmas as I saw them at that time. So thatís what Plasma Sources was set up to do, to treat the non-fusion stuff. And it turns out, as time went on, that the plasma part of the activity of the GEC were an extremely good match to the material that was placed in Plasma Sources Science and Technology, so over the years many, many of the people from the GEC became part of the editorial board and the things that we do in the journal are a good match to a significant fraction of whatís considered the GEC. Part of the GEC evolved with cross-sections and things like that we hadnít done very much with in plasma sources, but the other aspects weíve done a lot with. And so itís an actual place for people who are part of this community to publish in. Weíve never published any kind of an issue based on papers given at the GEC because people donít think of the GEC as a place where theyíre going to present papers that are just ready for publication usually. But many of the people who are important players in the GEC have become important players in the SS community in the subjects that we published. So over the years Iíve had a lot of contact with people; in fact I know them quite well. A number of people are senior members, like Art Phelps, who is a person who is very often involved with referring papers. Heís often a standard reference in the papers and who knows the most about the subject, but a lot of other people as well. This is the May issue of Plasma Sources Science and Technology. This has got a section based on an International Conference on Phenomena in Ionized Gases, ICPIG, which is one of the meetings that wonders around the world, and we often publish issues of papers that are motivated by papers that were given at those meetings. But itís not a conference proceedings. These are scientific papers that are based on the material that was present. If you look at the journal, one of the things, my view of plasma sources from the beginning of time of the journal was that the natural way to think of plasma is in terms of neutral pressure, and so on the inside cover thereís an ordering of papers by neutral pressure. The way theyíre published in the journal is by how theyíre actually accepted, and that may change in time, but electronically that was the most convenient way to do it, since theyíre published electronically online whenever theyíre received. The journal only comes out quarterly, but the papers are published as soon as theyíre accepted. So donít attach a logic to how theyíre published. Theyíre published by receive date. But in fact, if you look inside, you see some lower high pressure. So the things that low temperature plasmas do (these are non-fusion plasmas), they range from very low pressure to very high pressure. And nowadays the subject thatís really exciting to everybody is atmospheric pressure plasmas, which are involved in all kinds of things. Theyíre easy to do, and they have lots of applications. But low temperature plasmas have also been around for a long time, and everywhere in between. So from very close to vacuum to very good vacuum up to a few atmospheres. We have papers inside, a couple of pages in, thereís an ordering that list papers that way. I guess the thing Iíd like to talk to you about is to point out how many applications and how exciting this stuff is, and how important it is and everything else. If you look at the stuff that the American Physical Society does, when they try to justify how important plasma is when they go to conferences and stuff they always point out all of the applications. The applications and all that stuff is being done by the non-fusion part of the plasma community. In fact, the gaseous electronics part of the community. So this is the place this is being done. And the applications are just immense. Itís interesting that the applications thatís doing a lot of stuff nowadays are dielectric barrier discharges, which are atmospheric pressure discharges. Dielectric barrier discharges were invented by [???] in 1857, so they were one of the oldest form of plasma applications. Theyíve been used for ozone generation and things like that since then. But a lot of the details and a lot of the things about them are not understood, and itís only been in the last decade or so that theyíve started to be understood. It turns out that theyíre very easy to make, so places like China have gone overboard with lots and lots of experiments and lots and lots of applications. The applications of plasma, Iím sure youíve come into contact with a number of them, are enormous. If you look through the journal, if you look at the subject matter, thereís a wide range of discussion of plasma characteristics, but a lot of them are based on applications of plasmas. The biggest application right now are semiconductor types of things: 40% of the steps are doing or companion chip or plasma base. So in terms of dollars, thatís probably the biggest application. But thereís a big effort in things like computing tense levels with plasmas to change the wavability, whether the absorb water or they repel water and stuff like that. For cleaning things and putting different chemicals on stuff. Then thereís all over place doing applications. You can look through subjects here and this will give you an idea what the subjects are and who is doing it. Itís a very international effort, and the international community thatís doing these kinds of things is well represented by the GEC.

Cameron:

That was one of my comments to some of the earlier interviewees, the fact that when the GEC first got started it was strictly an American organization back in the í50s, but now itís pretty much completely internationalized, and certainly I would say at the time you started it was probably tending that direction. Has there been any noticeable change since you first started in terms of how itís become more international?

Hershkowitz:

Oh, yeah, I think so. Bill Graham is going to be the chairman next year and heís from Ireland. Peter [???] was the chairman, and heís American but he was in Japan for a long time. Yes, I think certainly the applications are being developed all over the world. There have been very large efforts in Japan and Korea and China now, and certainly throughout Europe, a little bit in South America but not too much, Australia. And people spend a lot of time visiting other places. Iíve enjoyed because Iíve gotten to go European places, got to go to interesting places and meet interesting people. And then to see people from all over the place as they wonder around, change your location with the same people.

Cameron:

You talked a little about people you thought were influential, or helpful, supportive, notable — who stands out in your mind?

Hershkowitz:

Leading figures, as far as Iím concerned, well in the old days, Will Alice would be a person. I can remember, that was my vision Iíd see, Iíd come to the meeting and heíd be sitting right there in the front row, asking questions. Now a person I think of at GEC is Art Phelps. Heís an extremely knowledgeable person, and he has strong opinions about whatís good science and whatís not good science, and thatís good, I really respect that. And heís a person who gives very good advice. Heís a nice kind of person to be [inaudible]. Iíve asked him to do favors for journal stuff many times, and heís always been very, very cooperative. Other people, if you look at the people on the editorial board, which I was instrumental in getting most of them on the editorial board. Of course itís changed over the years, but right now Bill Graham is on the board, Mark Krisner [?] is the editor now. The associate editors are myself, Bill Graham, and Richard Anderson from Hoboken [?]. The journal itself has always been about twice the number of papers from Europe as the US, and then papers from everywhere else. But on our board right now, the people, Dan Schram [?] was part of the journal very early, and he was always a strong figure in the GEC community. Jim Willard from Wisconsin physics department, heís been with the GEC a long, long time. Alan Bruscaden [?] is certainly a senior figure in the GEC. Dan Pitchford from Toulouse, France has been very helpful for a long time as well. Will Riser [?] from Russia is a senior person and quite knowledgeable in many aspects of GEC related stuff.

Cameron:

That makes me think about, it might have been Art Phelps saying that he had noticed that in the í70s is when a lot of scientists from the Soviet Union started coming to meetings and being involved in the community. Did you notice anything in the í90s, after the Soviet Union collapsed, people coming over here?

Hershkowitz:

Not so much over here. There are a number of people who have been on our editorial board in the past. Iím not so sure right. Mishu Benalow [?] from Portugal is from Russia originally; I don't know when he came over. Liger [?] has been on the board since the beginning. I don't know how many people have — there certainly have been people. There are people in the atmospheric pressure discharge community who are Russian based.

Cameron:

There had been a lot of things in both the general news and scientific news about people leaving jobs in the former Soviet Union because there were no jobs.

Hershkowitz:

Well, Barry Godeack [?] is a prime example. Heís not such a strong member of the GEC community I donít think, but he is certainly an active participant. He was a scientist at Moscow State University, did very respected work there, and then applied to leave the Soviet Union, at that time he was Jewish, and so they took away his job and forced him to work, I don't know, not very nice. And then eventually after many years he was able to get out. He got out in the early í80s. So heís one example of that. And then people discovered all the stuff that heíd done in Russia that was very important. Mike Lieberman thought he had discovered stuff at Berkeley, and it turned out that Barry had discovered it before him in Russia. So he is one example of a person like that, but I don't know too many that have been in that category. There are a number of Russians. Latsa Bacow [?], I think sheís from Paris, was a person on our board, and sheís originally from Russia, but I don't know under what circumstances she got out. That was before that time. Itís certainly has become more international. It is a very international community; itís nice. I always thought about plasma physics was even in the days when we were having no relations to speak of with the Soviets, in most cases in terms of plasma physics we had good interactions with them. When I visited China in í83, we werenít quite an official delegation, but the US didnít have any official delegation to China and we were supposed to be the first ones, we three people, but they didnít get the paperwork signed, the agreements form signed, so we went unofficially. They were very cooperative, lots of good discussions with the Chinese. The first Chinese came as visiting scholars to the US I think in 1979, and that was the start of a lot of the Chinese who had grown up in the cultural revolution, so there were people who grew up in that and had all of their things taken away from them, and no one got any PhDs or things like that. They had a whole generation of people who had been educated but somehow survived being farmers or whatever they did for ten years, and so they brought them to the US to educate them, or get them to a higher level of education. So they came, so that was one thing that did happen. I donít think many of them stayed here. I had one scientist who came who worked with me, he came in that group in í81, he was the second group that came, and he worked with me for two years, and then eventually both of his sons came and did PhDs with me, and they both stayed in the US, at least for the time being. So that was part of that. But itís not clear to me that there were more opportunities. In terms of basic plasma physics, the support that people got in recent years in Germany is better than anything that was in the US in terms of basics. Low temperature community really hasnít been so active and well supported. I think if you looked through here you can get an idea of all the kind of applications. Thereís an enormous number of applications.

Cameron:

That was another question I had, about the balance between basic fundamental research and applied industrial work.

Hershkowitz:

Well I think itís a good balance in this community. The Gaseous Electronics Conference is a good community with a good balance. The American Vacuum Society, thatís basically industrial applications, and thatís where most of the stuff thatís done is, and if you look at the work itís very specific kinds of applications. Thatís improved because used to be youíd go to talks there and they would put up graphs and they wouldnít put numbers on the scales, just tick marks and you couldnít tell, so that you didnít know really what the characteristics of their devices were. Thatís better now than it used to be. But in this community, there has always been an effort to try to get to the understanding of thing and get a fair amount of basic stuff going on. Thereís also applications, so thereís a mixture. And thatís because there are so many things you can do with plasma. I think the medical physics, which is starting to become a big thing, is mostly applications and not so much plasma physics. I personally thought that — I don't know, I like to see more basic stuff. But itís important, and the reason people do it is because they find that they have techniques that can actually be put into applications that can help people in a significant way, and feel like why spend the time understanding in detail what youíre doing if in fact you can go ahead and do something and be useful. So people are doing surgery with plasmas and things. And that makes sense. In terms of the applications, the textile people like it because you can change the surface functionality of things and make any surface look like something else, so theyíre doing stuff with that. And then thereís the plas band [?]. You can put coatings on surfaces to make them harder or more slippery, or other things, so why not do that.

Cameron:

Do you see basically that same balance since the í80s?

Hershkowitz:

Well the GEC used to be more cross-sectioned and less plasma processing, and as time went on the plasma processing increased, and so that particular application has expanded quite a bit more than the others. And the fundamental numbers that are behind doing things — you know, when youíre working with real gadgets, and the thing that the gadgets electronics community did thatís different from the plasma physics community, the plasma physics community concentrated on controlled fusion, so itís mostly worrying about the properties of hydrogen deterring plasma, whereas the GEC is working with real gadgets, and you have to worry about how real gadgets behave, and so thereís lots of cross-sections and things, and basic properties of the gadgets that have to be understood, and there are people in this community who are working on that. And then there are people who are taking advantage of using those gadgets to do things, and there have been an ever-growing number of applications of things that people have done that they havenít been able to do that wasnít so obvious that that was going to happen 10, 20 years ago. It seems like it was obvious, it seemed like it was going to happen, but it wasnít clear how far it would go, but it has continued and is likely to continue for some time to come.

Cameron:

Iím curious about funding, because thatís been a question thatís cropped up several times in different interviews that Iíve done. Have you noticed changes in who provides funding?

Hershkowitz:

Yes, it has changed in time. In the old days, when I first started doing plasma stuff in the early í70s, the National Science Foundation was the organization that you would have liked to get support from. They at that time did a very bad job of supporting new people. They had certain people that had been supported for some time and they continued, and if you tried to break into the system you couldnít. So I was unhappy with that. That was the physics NSF. The engineering NSF, in those days, actually did a pretty good job of supporting new people and new ideas, and so they were a possible source of support. The Air Force supported a little bit of work and the Navy supported a little bit. And then as plasma applications got to be more interesting, then DARPA and other kinds of government agencies started picking up bits and pieces of stuff. There was still lots of funding in the fusion and the cold power sectors, but in terms of the basic, the low temperature stuff, not a whole lot. And thatís sort of the way itís been, I think. The engineering NSF basically got out of supporting plasma physics, and the NSF lately has been supporting less than it did in the past. Thereís been the NSF plus DOE partnership in plasma physics supporting fundamental basically low temperature stuff. Thatís been in recent years, the last decade or so, that theyíve been supporting, and thatís been a pretty good source of support. The Navy I think has gotten out of it now, the Office of Naval Research that used to support it because there was a guy there who thought it was a good idea. He stopped, and then Basic Energy Sciences used to support plasma work, but I think theyíve been getting out of it as well. My big concern, actually, is not so much support. My big concern is that plasma physics as an academic discipline is having hard times, and that lots of electrical engineering departments have decided that it doesnít draw enough students and theyíve basically eliminated it from their programs. Most physics departments donít have plasma physics. Thereís been a little increase in that, but not much. So major schools like Berkeley and other places basically have gotten out of in their electrical engineering department of plasma physics, so I wonder if down the line as an academic discipline itís going to survive. It would be nice if we could do something about that. Thatís a real problem. Itís a question of how many students you can attract, what the needs are. There certainly are needs, butÖ

Cameron:

Do you see academia in other countries picking up the slack of that?

Hershkowitz:

No. I thought I did, but I think like in Germany they had a very nice program, they had a tenured program to do basic stuff, and Iím not sure, I think halfway through that that lost some measure of support. I donít know the details of that. There are certainly people here from that institution. There was a research center in Dublin doing plasma stuff, and I think that lost its support. You can talk to Mel Turner; heís here from that group. And with the economy the way it is now, who knows whatís going to happen. But if universities stop having plasma programs, then weíve got a serious problem. Iím very fortunate to be at Wisconsin. We have probably the biggest plasma program in the world as a university, and so itís a good place an there are a lot of people mostly doing GE stuff or some astrophysical plasmas and things like that. But itís at least acceptable at Wisconsin. At a lot of other places itís not, and thatís going to be a problem down the line.

Cameron:

Is industry at all providing any kind of funding?

Hershkowitz:

Yeah, industry provides some measure of funding. In California there are economic advantages to doing work with industry because the state will basically provide half of the support for research projects if industry provides the other half for work at universities. So a university can go to the state and stay I want to do this or that and industry will pay for half of it. So everybody wins, except the people outside of California. So industry does provide a certain amount of funding, bits and pieces, but not too much. The problem with industrial money basically is it comes with very short strings attached to it, and they want results. They want to own everything that theyíre supporting, which is a problem for Wisconsin because the university doesnít like that. But they want to own everything, so they want to own all the intellectual property, and they want projects that have results in six months, nine months. We get lots of little jobs, can you take this surface that we have that we make a sink out of, and can you put a coating on it so it will be harder, or more slippery, or the water wonít stick to it, or something like that. But they want a result in six months, shorter if possible. At a university you really want projects where the timeline is three or four years, the time of support for a graduate student. There is some amount of support from industry, but not too much. And industry, lots of companies are changing their personnel and their priorities change on fairly short time scale, so not the ideal way to support science. I guess the message I am staring at from Jeralyn [?] here, just tons of applications. You should read through this and get an idea of things that people are doing, sort of the kind of questions that people are asking. There are a lot of new questions that people are asking.

Cameron:

What are some of the new things going on?

Hershkowitz:

Well the atmospheric pressure plasma are the ones that people donít really understand too well. Atmospheric pressure plasma is interacting with liquids, and if youíre dealing with the plasmas in the medical systems, then youíre interacting with skin and tissue and liquids and whatnot, so those kinds of questions. There are still lots of fundamental questions. Like the thing that attracted me to plasmas in the very beginning is it looked to me in the early í70s that there were lots of questions that were simple questions that no one had ever thought about, and I have been working on with that point of view since 1971, and it hasnít changed. I tell my students in plasma class and physics class that you can ask me questions in this class and I can tell you, ďWell, nobody knows the answer to that. Thatís something that people havenít yet really understood.Ē There are lots of questions that are not so terribly difficult that arenít understood simply because people have to work on them, and itís nice to be a subject that — Itís like doing classical mechanics in the 1800s or something — still got lots of questions, there are things to be understood, and they need to be looked at. My hope is that there will be funding and opportunities for people to do it, but you never know. Maybe people will say, ďWell, we donít really need to understand that. We need to do other things.Ē The students wonít come along. Theyíll say, ďWe worry about other problems. We donít worry about this,Ē and put plasma aside and not worry about it.

Cameron:

And I suppose one concern for students is if I get an advanced degree in this subject, am I going to be able to find employment.

Hershkowitz:

Well right now in applications, students are finding lots of jobs. That hasnít been a problem. Students who do work in fusion come to me after they get their fusion degrees and say, ďWhere can I work in plasma applications?Ē and I give them the names of people in industry, and many of them find jobs. That continues to be true. I figure itís better than working for the oil companies. But a lot of people do theoretical work in the past used to work with oil companies, but they knew how to run big computer programs and code and stuff. And then thatís what used to be, and then they started going to Wall Street, and I don't know whatís happening now. But lots of applications, lots of things, lots of possibilities. Lots of things to still understand. And if the country continues to have any money to support basic research, lots of basic questions that need to be understood.

Cameron:

Can you think of any one question that stands out to you as being ďtheĒ question?

Hershkowitz:

No, I donít think there is a ďtheĒ question. I mean there are things that I care about, and other people care about other kinds of things. No, I donít think there is a single question that if we knew the answer to we would be way ahead. I donít think there is such a thing.

Cameron:

Anything else youíd like to add?

Hershkowitz:

Iíll probably think of a dozen things later. No. The nice thing about plasma is if you have an unmagnetized plasma with a single charge species in it, single kind of ion, and you put it into a container, and some of the details of how that behaves are not understood. And then if you put two species in, then itís much less understood. And if you put three species in, even more so. Now the thing that the gaseous electronics community does which the plasma physics community doesnít do, the gaseous electronics community has always put the neutrals in the plasma on the same basis as charge particles — you canít have one without the other. And so itís very important to recognize how the neutral species interact with the charge species and with the surfaces. So thereís a report that was generated a couple of months ago that was looking at things about low temperature plasmas, and Mark Krisner was one of the editors of it, so he could probably share that with you. But anyway, the sense of the title of the report (I forget the exact wording), but itís basically at low temperatures, plasmas are all four states of matter, because you have to worry about boundaries to the solids, and then thereís liquids, and then thereís gases, and then thereís charge particles. So there are all four states of matter — in the study of low temperature plasmas theyíre all there, and you have to worry about them all, and the interactions of the solids, thatís a lot of the fuss. If you have ions and neutrals hitting solids, and what happens at the solid nobody knows most of that — thatís a big unknown. And if you have liquids on the surfaces, then itís even more complicated. So those are big questions that need to be sorted out. But itís those fundamental things that really are the [inaudible]. But thatís what makes it fun. Weíre at the point where we can answer those questions, people can start in clever ways to make measurements and understand things, and clever ways to model these situations. Weíre making progress, but thereís a lot more to do. So is it exciting? Yes.