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: Vacuum plasma windows and microwave accelerators
Date: Sep 20, 2:48 pm
Poster: Jim Lux

On Sep 20, 2:48 pm, Jim Lux wrote:

>JL >You'll probably want to leave it in the closet... TWTs are notoriously difficult to adjust.. It also might be a cavity TWT and not a helix TWT.
>It is a helix TWT made in Germany with no documentation and yes, adjustment difficulties are probably the reason you can even buy these things cheaply at all - but remember, for simple irradiation applications we aren't talking about getting the thing to transmit in precise ranges of a few Khz - but only to put out a few hundred watts at frequencies that can vary all over the place - or in the case of a plasma window to dump a mix of electrons and photons into an already created plasma.

The tuning is to get it to work at all (guiding the electron beam down the center of the helix). Helix TWT's are inherently wideband devices.

If you want lots of Microwave power, I'd go with a Magnetron or a Klystron. Surplus tubes are available all over the place in various ratings, frequencies, etc. Megawatt peak powers aren't unusual or expensive for a magnetron (although the duty cycle will be low.. <1%)
>But you're probably right about this not being the most promising idea in the world as I don't think microwaves are anywhere near the frequenices that are required for resonance... however, back to the subject of plasma windows, do you recall the Kapitza atmospheric pressure reactor? I can't seem to find it in my files.