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: A few questions, Richard Hull
Date: Oct 21, 8:00 am
Poster: Richard Hull

On Oct 21, 8:00 am, Richard Hull wrote:

>Thank you very much for answering my questions. Just a few more ones. You mention that star mode is unavoidable in a glow mode fusor. What is "glow mode"?


Glow mode is a combination of pressure and voltage in any evacuated device where there is just enough gas remaining to support moderately high current conduction via a plasma. Common examples are flourescent lamps, neon signage, etc.

This mode disappears when common field emission and conduction via gas ions fails to pass a significant current and the visible glow in the device disapppears optically. In most regimes of vacuum devices, this occurs at or near 1 micron (10e-3 torr). Increased voltages can carry it submicron, but not by much.

The mean free path for ions in glow mode devices rarely exceeds a few centimeters. Thus, there is a lot of collisions with attendent ionizations and recombinations. The glow is given off mainly by recombinations.

With heated dispenser cathodes in the device, the fusor can operate into the deep vacuum regions, but the glow is not there to the degree where it is an optically satisfying or significant display. RH

>Also, I am trying to make neutron producing fusors so is 40kV the lowest voltage that would work and what is the lowest amperage?


Neutrons are easily detected in the fusor above 20kv. The currents where I have found counting obvious and easy can be as low a 8ma. The limit is related to the heating of the inner grid. Too much current at a given voltage and the inner grid is vaporized. This is why a demo model is so critical to the study. you need to be able to play with the plasma to get a good old fashion feel for controling the processes. RH

>Lastly, are X-ray transformers capable of doing this? Do you have any idea where I could get a used one donated, or where I could buy one? (Perhapse places that take X-rays, if my inference on what they are employed for is correct)?


X-ray transformers are capable of fusor work. I assume you read the recent post on x-ray power supply purchasing in North Carolina?

I have no specifics on purchase beyond those already expressed on the list. The obvious place is a place that sells, repairs and maintains medical X-ray equipment for dentists mainly.

Richard Hull