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Oral History Transcript — Dr. Raoul N. Franklin

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Interview with Dr. Raoul N. Franklin
By Gary L. Cameron
At the Gaseous Electronics Conference
October 15, 2008

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Raoul Franklin; October 15, 2008

ABSTRACT: In this interview Raoul Franklin discusses topics such as: getting his doctorate at University of Oxford; [Alfred] Hans Von Engel; atomic and molecular physics; ionized gases; Sandy Brown; plasma physics; David Bohm; City University in London; Manfred Biondi.

Transcript

Cameron:

Iíve been asking people to give their own story first, and then I fill in with any questions I have, generally talking about when did you first get involved in the GEC, memories of how it was in the old days, how things have changed, things like that.

Franklin:

Well, I did my doctorate in Oxford, and my supervisor was Hans Von Engel. He was a person of international reputation, and that meant that quite frequently one met people who were associated with the GEC as they passed through Oxford. For instance, Will Allis spent, I think, a term with him. I believe perhaps Von Engel attended an early GEC conference, and basically it was that that led him to establish the International Conference of Phenomena in Ionized Gases [ICPIG]. That first met in 1953, so I think by looking back at the epitomes between í48 and í53 you most probably will be able to find the evidence I havenít sought but I believe will be there that he attended one of those conferences. So it seems to me one of the important functions has been this forming of other conferences. At a later date there was, now called the ESCAMPIG, the European Sectional Conference of Atomic and Molecular Processes in Ionized Gases. Those two conferences, ICPIG is in the odd years and ESCAMPIG is in the even years. ICPIG was a conference that was essentially European for quite a long time, but it really did became international when it met here in the United States at Hoboken, I think in 1997, and it met again in Nagoya in 2001, and it will be in Cancun next year, 2009. From an early date I was aware of people working in the field, and Langmuir in one of his papers has an equation: I = SEX. [Chuckles] Langmuir, I think fairly clearly, he may have attended GEC, as he was honored at one of the early GECs, but he was no longer really interested in plasma physics at that time. The people that I knew and met were through Sandy Brown, and so on. So I felt that I was part of that family in some sense, even though I only first attended GEC in 1998, but Iíve been every year since then. But since I became aware of it, I used to go into the library at the appropriate time of the year and read through the epitome, and if there were papers that were of interest to me, I would write to the person concerned and ask whether they had a fuller version of it, because all you get is abstract there, and sometimes Iíd have to wait for it to be published. It was quite natural for people to be reticent and wait to see if their work was peer reviewed and published. So I followed it regularly. In terms of the correct form that you got, as to important issues, there are two things that I remember very clearly. After the Second World War, magnetrons had been developed for radar, and then people started thinking of applying them in various ways. Of course we wouldnít have the microwave to cook with if it hadnít been for them. But very early on, the MIT group used magnetrons to create plasmas, and then look at the decay after the microwave power had been switched off. That was used essentially to measure recombination coefficients. So that was a great industry, successive research students that went through MIT and worked their way through various gases. But the field was thrown into total disarray when one of Sandy Brownís research students, Persson, a Swede in origin, varied the power and the recombination rate varied — should never have happened. So what was realized is they were operating at powerful volts that essentially blasted impurities off the walls. So a whole body of work had to be discarded and it had to be done again.

Cameron:

It was basically contaminated.

Franklin:

Yes. So I can remember that clearly and basically it was at the time that I was a research student.

Cameron:

When was that?

Franklin:

I started my doctorate in 1957, so í57 to í60. The other is a related thing that had also to do with an afterglow. Now, recombination is the sort of thing that occurs in volume, but there is essentially a competing process which is diffusion of the charged particles to the walls, and it was quite some time before it was realized that you had to make measurements over something like five orders of magnitude (in other words, 105) in terms of time scale before you could actually distinguish between recombination in the volume and diffusion to the walls. I should have brought the names of people associated with that. My memory is that one of them was gray, I think E. P. Gray, but Iím fairly confident that that must have emerged first at the GEC conferences. So I think thatís really all that Iíve got to say, except that I mentioned the business of spanning other conferences, and just now, within the past few months, all three conferences have agreed to share their address lists, so there is now effectively a worldwide community of people that get early notice of all three conferences. That that grew out of the GEC is I think a very important thing.

Cameron:

Itís come up in previous conversations. One person had a question about when plasma physics split off from the GEC. In fact, Waymouth and Phelps were able to fill me in on that, and basically it was just that plasma physics just became too big.

Franklin:

In a sense, the plasma physics conference now is dominated by fusion. Well, there was a period when people were arguing about whether their plasma was a real plasma or not. Now of course, when Langmuir appropriated the word, it was in relation to gas discharges, where the degree of ionization was not an important issue. As far as fusion is concerned, of course in the center of plasma, they are in quite a different regime. But it has taken them quite a long time to realize this, in the edges youíve got something that is very similar to the sort of plasmas that people are talking about here. So those who were really thinking hard about these things are coming together now, and in that conference thereís someone talking about the effect on the lining of the fusion vessels, and itís all the sort of basic physics that is better understood here, shall we say, than in the fusion entity.

Cameron:

My primary interest in the history of science is the social history of science, so in a way I guess I like looking at the dynamics of the people within the community and how that works.

Franklin:

Something I think Iíve come to rather late — Goodness, did David Bohmís name come up at all? Over the years there will have been many papers associated with so-called Bohm Criterion.

Cameron:

Actually, the only list of names I have is from the very first conference. So if he was after that, I donít have that.

Franklin:

In í48 he would have been at Princeton. Bohm worked with the British group at Los Alamos during World War II, and it was while he was working in that group that he enunciated the Bohm Criterion. It looked as if he was going to have a glorious career. He went off to Princeton and to the university, not the Plasma Physics Laboratory; having been attracted there because of Oppenheimer had gone there. Bohm produced several good papers, but one day the president called Bohm to his office and said, ďClear your desk and never darken our doors again.Ē Bohm had refused to testify before the Un-American Committee against colleagues. Now they were quite civilized. They said they would give him his salary for the remainder of his present contract, which was probably three years. He then went off to Brazil. He had had a research student who was Brazilian. When he landed there, the immigration authorities said (Iím corrupting this a bit), ďOur masters in the United States have told us to confiscate your passport,Ē and he was imprisoned in Brazil. Then he remembered that his parents were of Jewish origin, and that would entitle him to go to Israel. Bohm then went to Israel. Again he picked up a good research student, and that research student and Bohm have an effect in physics named after them (the Aharonov-Bohm effect). But Bohm wasnít terribly happy in Israel. He was attracted to England by a professor of physics. He said, ďWhile I canít do anything for you immediately, but I can get you a doctoral position.Ē So he has this career that was going up and down [gesture] like that. But that gave Bohm the breathing space. The research student that I mentioned also joined him in Bristol. They published a paper, really a groundbreaking paper, and the experiment was done within two years. So there was his name forever in physics. But while he was at Princeton, he had to lecture on quantum mechanics, and that got him interested in the foundation of quantum mechanics. So when he died a few years ago, he was better known to philosophers of science rather than mainstream scientists. But nevertheless, at the age of 73 he was elected to a fellowship of the Royal Society. Now they donít normally elect people that old; they try to capture people on their way up in their 50s. The next year Bohm was awarded the Gold Medal of the Franklin Institute in the United States. Thatís remarkable, isnít it?

Cameron:

It makes me think about a question that came up very early in my research. Varney and Fisher, I was talking to them about the makeup of the people doing gaseous electronics in the late í40s, and their impression was that in America you had very much a blend of theoretical and practical research. On the continent of Europe it was very much practical research, and in Britain it was very much theoretical research. Is that how you see it?

Franklin:

Not really, because the talk I gave yesterday was on electronegative plasma, and the early work there was done by Emeleus in Belfast, and that was largely experimental, and by Massey, who was of Australian origin. A lot of the stuff that Massey did was theoretical, but there was quite a lot of experimental work associated with it. And of course they were beginning to explore the ionosphere. It seems to me thatís an oversimplification.

Cameron:

I think that even in the history of science, the picture of Britain after World War II in terms of science is that the budgets were being tightened and so forth, as compared to certainly the United States, where the pocketbook of the government was pretty much open.

Franklin:

Well, Von Engel fled from Germany very late, and he supported himself and his research group entirely on external money, which he got some of it from the Atomic Energy Authority, some of it from the Central Electricity Generating Board, and other organizations. So some people, if they were of sufficient standing, were able to draw on other sources.

Cameron:

How much cooperation was there in Britain between academia and industry?

Franklin:

Von Engel was a good asset whenever he would go and visit them, and then come back and say, ďOne more thing,Ē or, ďI can think about that aspect. And furthermore, Iíve got research students, and I can recruit some to do it.Ē And there was quite a strong cooperation between Oxford University and Culham Laboratory, and Harwell, first of all of course, and then Culham. So there was cooperation. And there was a strong lighting industry in the General Electric Company. The United Kingdom did have good people who were concerned with the science of lighting. It happened around about 1970 that GE got in a company doctor — sorry, thatís a technical term, someone who is really restructuring the industry, and basically he chopped research and he chopped a scheme whereby they supported sandwich students at university. Sandwich students took a year longer, they had some experience in industry, but they had, provided they had performed sufficiently well, a guaranteed job at the end. You can imagine how devastating that was. When I went to City University [London], basically I had to close physics because of the effect of that decision. We had had 40 students a year coming; suddenly it went almost zero, it wasnít absolutely zero, and it soon became nonviable.

Cameron:

How have you seen the GEC changing? You said you became involved fairly late, but maybe from a distant observerís point of view.

Franklin:

I think itís been a relatively slow evolution. All of the three conferences that Iíve mentioned now are quite heavily directed towards various aspects of plasma physics — not surprising, given the size of the industry worldwide.

Cameron:

And plasma processing involvingÖ?

Franklin:

Manufacture or computer chips, and all of that. There are various branches. The path that is financially significant is the manufacture of computer chips. It is the technology there that came really to fruition in the late 1990s that enabled computers to get smaller and smaller.

Cameron:

And this is basically the process of cutting out the —

Franklin:

Yes, the detail work with the silicon, and then filling the trenches with the other things that actually make plasma circuits. And itís a technology which most probably has another 20 years to run. Itís possible to make predictions as to when the scales will get too fine to use the current techniques. And there are people who are working on alternative technologies, but theyíre still quite a long way from application. So if I were advising someone at the present moment should he be going into the field, I would say yes, it isnít one that is likely to shut off in the foreseeable future. It will adapt and people will find other applications. There are people working on more advanced space propulsion systems. You know, when youíve got vehicles that really are outside the Earthís gravitational influence, then you can think of propelling these things, injecting ions out of the back of the vehicle.

Cameron:

Iíve asked a few people about student involvement. For example, to the conferences, do you try to bring a contingent of grad students with you?

Franklin:

Certainly I used to. And goodness, I mean there is left behind the department. When I was in Oxford, we ran the ICPIG conference that was profitable, and so we used the profits to establish a fund to enable younger people to get into conferences. I havenít supervised anyone myself for probably 20 years, but when I retired from my place in university, which in the end was largely administrative, I joined the research group in Oxford, and I said to them, ďI donít want to supervise research students. I donít want the responsibility. Iím perfectly prepared to talk to them and advise them. Iím perfectly prepared to examine them.Ē I carried on in that mode, and made friendships with younger people that way. I see these conferences as an important thing in terms of bringing on younger people. And it happens that ICPIG has a new prize for a younger person. He or she had to be within eight years of commencing their PhD I think, and I nominated the first person who was successful and interested in it. And young people will come up to me and introduce themselves and say, ďAh, I have a question Iíd like to ask you.Ē

Cameron:

Iíve noticed at the conference there are a fair number of grad students here. I don't know what exactly the proportion is, but it seems like itís a good test ground for it.

Franklin:

Yes. Another thing that is particularly true of this conference, I mean there are some advertisements downstairs in the doctoral division and so on, and there are fewer than there used to be. A new part of the process was showing yourself and hoping that way you might get a position.

Cameron:

Thatís one of the key things about GEC right from the very beginning. I interviewed Fred Biondi earlier this summer, and he said at the first GEC he was a grad student, and by the time the next conference rolled around he had a job because of the contacts he had made and was one of the hosts of the second GEC. So it seems to be a good tradition. And I think the mix of people involved in industry as well as academia here seems to help that as well.

Franklin:

Though there are still concerns, and GEC however many years ago was in San Jose, and it was remarkable how few people from Lam Research Corporation were there, and theyíd just sort of pop in for a day, seriously frightened I think of people trying to pump them — they werenít prepared to talk about current work.

Cameron:

Is there anything else, so you think?

Franklin:

I donít think so.

Cameron:

Well thank you.