Sciencemadness Discussion Board

Elemental transmutation via Farnsworth fusor

killswitch - 26-2-2012 at 13:56

I have long been interested in the Farnsworth fusor, though mostly for curiosity purposes. Recently, however, I have been mulling over the idea of using the neutron flux for elemental transmutation.

I understand that this has potential to present an extreme health hazard, and is not very affordable. But does anyone have any suggestions for target transmutations?

entropy51 - 26-2-2012 at 14:28

If by transmutation you mean activating enough target nuclei by neutron capture to be detectable, then this is possible. The neutron capture reactions will result in the formation of a beta emitting isotope of the target nuclei. It would most likely require the use of a target material with a high thermal neutron absorption cross section, such as indium, gold, silver, manganese as well as a moderator such as paraffin to slow the 2 MeV neutrons produced by the deuteron-deuteron fusion reaction down to thermal energies.

If by transmutation you mean the production of macroscopic amounts of elements different from the target nuclei, forget it. The neutron fluxes produced by any reasonably powered Farnsworth Fusor are just not in the same league as a nuclear reactor.

killswitch - 26-2-2012 at 14:31

Quote: Originally posted by entropy51  
If by transmutation you mean activating enough target nuclei by neutron capture to be detectable, then this is possible. The neutron capture reactions will result in the formation of a beta emitting isotope of the target nuclei. It would most likely require the use of a target material with a high thermal neutron absorption cross section, such as indium, gold, silver, manganese as well as a moderator such as paraffin to slow the 2 MeV neutrons produced by the deuteron-deuteron fusion reaction down to thermal energies.

If by transmutation you mean the production of macroscopic amounts of elements different from the target nuclei, forget it. The neutron fluxes produced by any reasonably powered Farnsworth Fusor are just not in the same league as a nuclear reactor.


What about a Bussard-type polywell device? Could it produce greater neutron flux?

[Edited on 26-2-2012 by killswitch]

[Edited on 26-2-2012 by killswitch]

entropy51 - 26-2-2012 at 17:09

Quote: Originally posted by killswitch  
[What about a Bussard-type polywell device? Could it produce greater neutron flux?
Yes, it could. But the production of really signifiicant neutron fluxes with these devices requires use of the deuteron-tritium fusion reaction and safely handling tritium is not a home project. There is no way to legally obtain tritium for home use.

Just the production of detectable, say microcurie, amounts of activity with a fusor is a very worthwhile project, but anything beyond that is very difficult.

Although the neutron flux is not terribly high, the x-ray output from even a modest fusor can be hazardous.

neptunium - 27-2-2012 at 06:14

i `ve seen amateur fusor capable of 1e6 neutrons/s and this is not a small thing..
a fusor usually has a neutron outup of a spherical shape if you could focus these 1 million neutron on a small target of Mn55 for example then it should be interesting .

a gamma spectrometer is needed to identify and quantify the isotopes generated.
if fusion is your interest then yes become a part of a select group of home fusioner..

if activation is the goal then build a particle accelerator and speed up ionized helium towards a beryllium target !

none of these project are impossible but costly, time consuming, and challenging!
but fascinating!