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: Another 2 cents on microwaves
Date: Aug 16, 10:03 pm
Poster: Jones Beene

On Aug 16, 10:03 pm, Jones Beene wrote:

Wow, these two cents worth are adding up...

Jim Lux wrote:
>It would be the rare Gunn diode that is cheap and puts out more than a 100 mW, and I don't know that power that low would make any difference. As for combining the outputs, it would be a significant technical challenge, because you have to get the phases the same, a VERY non-trivial task with Gunn Oscillators. And, even then, the power would add only at a few points, depending on the geometry.

You are missing the main point entirely, Jim. At $10/ pop, the low output Gunn diode might be the cheapest item in your experiment...by far. Phase synchonization is NOT an issue with widely seperated diodes focused on a plasma whose radius is signiicant in excess of the wave length, so long as the radiation is well absorbed, and all indications are positve for that. But most importantly, in the spirit of Farnsworth himself, the whole point of playing around with these devices is the hunt for the unobvious - the anomaly. If you find that a 300 mW diode array gives you an order of magnitude more neutrons..well, then you have stumbled onto something really important. If nothing at all shows up, then you can say, like Edison,that the only thing he could tell someones about light bulb filaments is the several thousand materials that don't work. There are no simulation programs out there that are going to help you get anywhere near what a few extra hous of effort and a little luck might produce.

>If you want to use microwave power, use cheap, readily available microwave oven magnetrons (>1kW for <$100). Just know what you are doing before you cook yourself.

Again, its not the magnetron but the power supply and waveguide that is the problem. Not to mention the fact that an extra kW from a magnetron will fry your grid in less time than it took to answer that suggestion.

>Determining how to couple the power into the plasma is a bit tricky, since the plasma is a conductor, and reflects a fair amount of the incident power. A suitable cavity will reflect it back to the plasma, but, I suspect that the challenges in this would far outweigh any advantages.

Yes, the coupling part is tricky, but he plasma will relect incident power back roughly in proportion (ignoring resonance) to wavelength, so the Gunn diode gives you a factor of roughly 8 better chance of achieving good coupling

>It's worse, the wavelength is small (3 cm for 10 GHz), so propagation in your chamber (which is many wavelengths in size) will be hard to predict, unless you have a good (read high $$) simulation program. It is much easier to design a single mode cavity when most of the cavity dimensions are on the order of or smaller than a wavelength. (say, 2.45 GHz == 12 cm)

Forget simulation programs. If fusors could be simulated this forum would not exist and none of this would be of interest anyway. BTW, wouldn't most simulation programs tell you right off the top that you will achieve NO, nada , zilch, zero, DD reaction neutons below the theshhold level which if memeory serves is around 750 kev?