Talk-Polywell.org

I know that the original Farnsworth Fusor was orders of magnitude away from producing as much energy as it consumed. It was however an excelent source of fast neutrons if fueled with deuterium or D plus tritium. Has anyone ever put a blanket of U238 around a fusor? The fast neutrons would fission the uranium but there would be no chain reaction because the neutrons released by U238 fission are not energetic enough to split further uranium nuclei. Is there a chance that enough energy would be released to break even? If not, you would still have a portable gamma ray source that could be turned on and off at the flick of a switch. This might have industrial applications where isotopes like cobalt60 are used today.

THey're looking at using a variety of fusion sources for this.

DR.ZARKOF wrote:I know that the original Farnsworth Fusor was orders of magnitude away from producing as much energy as it consumed. It was however an excelent source of fast neutrons if fueled with deuterium or D plus tritium. Has anyone ever put a blanket of U238 around a fusor? The fast neutrons would fission the uranium but there would be no chain reaction because the neutrons released by U238 fission are not energetic enough to split further uranium nuclei. Is there a chance that enough energy would be released to break even? If not, you would still have a portable gamma ray source that could be turned on and off at the flick of a switch. This might have industrial applications where isotopes like cobalt60 are used today.

Hirsch Farnsworth type fusors are ~ 1 million to 1 billion times more energy in than fusion energy out. I'm guessing for a fusion fission hybird the fusion afficiency would have to be within a factor of perhaps 5-10 to provide enough neutrons for the much more energetic fission reactions to make up the difference. A marginally performing Polywell, FRC or focus fusion approach would be more promising.

Dan Tibbets

OK. So there is no hope of using this idea as a power source. But what about as a gamma ray source? Could it produce enough radiation to be useful in things like food sterilization, medical radiation treatments or finding microfractures in steel and concrete?

One plan was to take a tank, and line it with a whole bunch of fusors. These would be providing extra neutrons, burning the fission fuel in the middle more efficiently. This can also burn fuels that cannot fission in a traditional reactor.

Variations on this use different neutron sources, but anywhere a good neutron source would help, a fusor is an effective way to get neutrons.

DR.ZARKOF wrote:OK. So there is no hope of using this idea as a power source. But what about as a gamma ray source? Could it produce enough radiation to be useful in things like food sterilization, medical radiation treatments or finding microfractures in steel and concrete?

Gamma rays- I don't think that the typical fusion reactions if a Fusor produces gamma rays. Some of the CNO reactions (occurs in heavy stars) produce gamma rays but the reactions are several orders less efficient at obtainable Fusor conditions compared to D-D fusion.
Certainly Fusors can produce lots of steralizing x-rays (just not as penitrating as gamma rays). I'm not sure how efficient/ expensive they would be compared to other x-ray generating approaches.

Dan Tibbets

The gamma rays would be provided by the fissioning U238. Portable gamma sources such as radioisotopes are dangerous unless shielded. A fusor could be turned on and off instantly. You wouldn"t have to worry about someone stealing it to make a dirty bomb either.