Fusion Message Board

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, 2:55 am
Poster: Pierce Nichols

On Nov 20, 2:55 am, Pierce Nichols wrote:

>The Miley device I have seen is not actually a spherical "Fusor" but rather a conical section of an IEC machine. If you could imagine pushing an apple-corer thru a Fusor, that is what he was trying to do. Ions from either end of a cylinder converged on the center, pulled by ring grids just to either side of the center. Just before the ion packet reaches the grids they reverse polarity, so the ions avoid the grids and collide in the center.
>This device attempts to avoid grid losses by its pulsed operation. If that can work, the concept has great merit and would be better than any steady-state fusor.

That I was not aware of. Thank you for extending my knowledge. It gives me an interesting idea -- do a strong fast pulse followed by a short voltage reversal to keep the incoming ions off of the grid. The problem is that it requires an extremely fast pulse time.
So doing it as discrete pulses appears to be quite difficult. That leaves RF. I don't think it would be productive to go as far in the reverse voltage direction as in the forward voltage direction, so add a big DC component, so the waveform dips a little into the reverse voltage before heading up again. Prolly easier to do then short pulses.
Alternately, you could run the high power RF output through a diode (so no reverse voltage pulses), and combine it with smaller amplitude reverse voltage pulses from a different source.

>I would personally be more inclined to work with RF rather than any relatively slow pulsing. I believe the Fusor depends on elimination of background neutrals by heating (reducing their density until they are no longer a significant loss mechanism for ions), a critical part of getting long mean free paths. If pulsing allowed the neutral population to climb it would be a killer. Pulsing would have to be to fast to allow this.

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.