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Historical AttributesHarvard Professor of Physics Kenneth Bainbridge developed this apparatus in the late 1930's for use in separating nuclear isotopes with a Holweck pump. With the discovery of nuclear fission, Bainbridge realized the method might be valuable in separating Uranium-235 from Uranium-238 for use in atomic weapons. He enlisted the help of George Kistiakowsky and E. Bright Wilson. In 1991, Bainbridge described their work as follows:
"Before fission was discovered, I was working on separating isotopes. I'd built up a Hevesy isotope separator. I had a theory of a way of separating isotopes using a Holveck pump, which is simply a cylinder rotating at hellishly high speed with close clearances and helical grooves around the stator. This is a very effective pump. I did a theory on what it would do to separate isotopes. When Uranium fission was discovered, U235 was the fissionable material. If you wanted to concentrate that — it's only present to 0.7 percent — you could do it with a pump like this. The light isotope, the one you want, would congregate more at the low-pressure end, and the heavy stuff would be at the high-pressure end. So you had a separating device. I told this to George B. Kistiakowsky and Bright Wilson. Wilson did an exact theory of this thing, which was not as optimistic as my crude theory, and we tested it. We got a Holveck pump from Alfred Loomis. Kisty (Kistiakowsky) had been with Alfred Loomis, and I asked him if he could get this pump from Loomis, which he did. I don't think it's ever been returned. Loomis never wanted it back after all. Anyhow, it was set up in the chemistry building and Kisty was put in charge. He got someone to help him run the damn thing. Wilson did the precise theory. I had a mass spectrometer to measure how much separation it produced. The separation of the argon isotopes came out according to Wilson's theory. So we had a theory, and we had a way of testing it, and so on. Then Kisty went to Washington, DC to sell this to the government. He went to the Navy, and they said, "Well, boys, just relax. We've got people working on this sort of thing. You just go back and forget about it." They pushed us off! So we quit on that. "
Primary SourcesKenneth T. Bainbridge: An Interview Conducted by John Bryant, IEEE History Center, 10 June 1991; transcription is on this
IEEE website.
Papers of Kenneth T. Bainbridge, Harvard University Archives, finding aid can be seen here.
Kenneth T. Bainbridge, "Prelude to Trinity," Bulletin of the Atomic Scientists, April 1975, pp. 42-46, esp. 42-43.
ProvenanceFrom the Department of Physics, Harvard University.