In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: An interesting benefit to pulsed fusors
Date: Nov 20, 7:42 pm
Poster: Tom Ligon
On Nov 20, 7:42 pm, Tom Ligon wrote:
>I guess the question is how fast neutrals recombine during the quiet periods. The discussion earlier included a small "sustainer" current constantly on, which I think would suppress re-combination of neutrals. I may of course be completely off my nut.
I take it you mean how fast ions recombine to neutrals? At high keV there is a fairly small recombination crossection for ions and electrons. But upon turning off the high voltage the ions would slam straight into the nearest wall. Faster than waiting for a passing electron, I'll reckon', and a total loss of the energy of the ions.
A small "sustainer current" at reduced potential would probably increase the recombination crossection. Might still work if the numbers are right.
With Miley's version of pulsing, at least the system I've seen, the idea is to pulse in sync with the transit times of ion packets, i.e. pretty fast. This avoids losing the ions to the walls. The potential is attractive with the ion packet outside the "inner grid" (or whatever the machine uses) and reverses as they pass inside.
One of the biggest loss mechanisms in IXL or EXL machines is the high collision crossection between fast ions and slow neutrals, giving slow ions and fast neutrals. Neither is very useful. Thus, you want to get rid of neutrals.