Wow! That's gotta' be the smallest demo fusor on record!!!
I am for working small, but that is "ship-in-a-bottle" size!
I am in somewhat regular contact with Scott little and have visited and worked with the Zambelli fusor and , of course my own Fusor III system. All are neutron producers.
The general threshold for a detectable neutron count is generally around 10kv applied to the fusor, but it is in the mud for most detectors. Obvious counts in excess of background to the untrained but well equipped casual observer/experimenter occur around 17kv. The thing really is cookin' at about 23kv and is neutron unfriendly at about 30-35 kv. Most of the output levels recorded are runs for max production and so only the realm of 20-30kv has been explored long term by the three of us. 20Kv can have about 5-10 thousand neutrons/sec. This rises sharpely at 25kv to about 40,000 or more and between 28-30kv just starts to exceed 10e5 neuts/sec.
The currents are usually between 8ma and 15ma and are pretty much limited by inner grid heating. Needless to say the neutron count more or less scales with current provided you are on a decent part of the operational cross section for d-d fusion. (voltage)
I felt I could not warrant any neutron production below 10kv, though there is surely some according to theory. It is just a matter of detection efficiency.
Certainly our output is way too low for use in heating water and even for neutron activation work. Thankfully, at a range over 1 meter from the core, the flux is minimal. Power levels in long run amateur fusor operations don't average more than about 250 RMS watts of electrical input energy so the device is not creating brown outs on the local grids while in operation.
For the short moments that we reach and exceed 10e5 neuts/sec total isotropic emission, we might be drawing 350 watts from the wall outlet and pouring it directly into the plasma. This naturally is not including the pumps or instruments which are necessary to support the run.
I hope this helps.
Richard Hull
Created on Monday, January 22, 2001 1:34 AM EDT by Richard Hull