Radio waves to increase fusion yield

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Andrew Seltzman
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Re: Radio waves to increase fusion yield

Post by Andrew Seltzman » Tue Oct 23, 2018 11:13 pm

Yes, the window would be possible, however you would need to ensure the nipple the window is mounted on will transmit the RF frequency. The nipple would act as a cylindrical waveguide, the cutoff frequency, determined by radius would have to be below your operating frequency (it should be below by some margin to reduce losses).
https://www.pasternack.com/t-calculator ... cular.aspx

The window itself would also have to be designed for low reflection of RF power, typically this is done with a numerical finite element solver such as comsol multiphysics.

Using ion sources or filaments for ionization control are better ways of increasing fusion rates since they are better able to control the location where deuterium ions are generated.
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Robert Dwyer
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Re: Radio waves to increase fusion yield

Post by Robert Dwyer » Wed Oct 24, 2018 8:07 pm

I really would not suggest using microwaves, due to the potential danger, until you get more experience working with Rf plasmas under your belt.

I work in a lab that studies RF generated plasmas and have conducted research on various topics of interest to those in fusion (turbulence, Ion-neutral collisions, probe theory, etc..). People here have built RF coils coupled around a glass tube to generate an inductively coupled plasma before as the ion source for beam target fusion. With proper Ion optics, I am sure these plasmas can be focused into the inner grid of an operating fusor to increase ion density in the grid. How much will this increase fusion?
Only you can say for your setup.

If you are interested in doing something a bit different and want something to fuel your fusor with a higher energy and density than an ICP, then a Helicon Ion Source may be the next easiest (and definitely less dangerous) option. A Helicon plasma is generated when an RF coil (typically driven at 10.0 MHz to appease the FCC for the large sources) is in the presence of a magnetic field that is axial to the coil. Usually minimum coupling is done around 50 gauss, but can be driven up to thousands of gauss (giving way to many different interesting forms of turbulence and fluctuations). This magnetic field causes the initial Inductively coupled plasma to enter 'W' mode, which has the advantage of far higher densities and temperatures (typically 3-5ev). For the amaeture, this could easily be done with a set of large ring-type neodymium magnets. The hardest part would be building the driver and tuning the antenna. The ions would be accelerated by your large potential difference and gain energy based on your voltage drop. You benefit not from the temperature, but the improved density and ion species in your device.

Overall, if you want to seriously, and in detail design any RF driven source, you must use some type of ion optics software to get an idea of what will happen. Or, you can just built it and try it! However, I do recommend against using any sort of microwave source to start, as steady state microwave sources of any significant power can be a serious hazard. There are easier and safer ways to create an RF driven plasma than microwaves.
If we throw more money at it, it will have to work... right?

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Bob Reite
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Re: Radio waves to increase fusion yield

Post by Bob Reite » Thu Oct 25, 2018 10:44 pm

No, you don't want it on 10.0 MHz, unless it's shielded real good, or you'll interfere with WWV. The nearest ISM frequency is 13.56 MHz. There other services must accept harmful interference caused by industrial, scientific and medical uses.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

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