Fuel Introduction

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Fuel Introduction

Post by guest » Thu Sep 20, 2001 11:47 pm

Does anyone know the performance differences between introducing D via an electron gun and using the double ringed system that the U of Wiscon is has?

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Richard Hull
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Re: Fuel Introduction

Post by Richard Hull » Fri Sep 21, 2001 6:56 pm

I guess your question was not clear to me. I assume you mean introduction of Deuterium ions via an ion gun.

Another method is creation of the ions in a region close to the outer shell with a hot or thermionic electron emitter wire to perform the ionization against a second ionizer grid.

An electron gun per se would be of little value in a fusor though a crude form exists as just a small part of most ion gun designs which are then attached to the outside of the fusor shell.

To answer your question, Whatever method produces the highest deuteron current at the outer shell in a fusor is the winner. The methodology for accomplishing this can vary widely. Ion guns can supply healthy amounts of current, but only in microscopically small cross sections. They must, therefore, be precisely aligned and carefully controlled.

Volumetric ionizer systems of thermionic emitters and accelerator grids have the advantage of distributing their ion currents over the surface area of nearly that of the outer shell.

It is a matter of form and function and only results wins the game.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

guest

Re: Fuel Introduction

Post by guest » Mon Sep 24, 2001 10:54 pm

>> Another method is creation of the ions in a region close to the outer shell with a hot or thermionic electron emitter wire to perform the ionization against a second ionizer grid.

I'm not sure I follow your reasoning here. I haven't done much reading on this and I'm not up on the jargon. Could you explain this? Thanks for answering my post. I was afraid you guys had abandoned this site.

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Re: Fuel Introduction

Post by Richard Hull » Tue Sep 25, 2001 1:44 pm

We have not abandoned this site.........We abandoned the intranets site in July. This is the new site. It is up and running fine thanks to Ryan and the Perfesser.

Ideally, ions are not to be created at or near the cathode in the fusor. As it is an accelerator-collider, the ions need to accelerate or "fall" through the full potential between the shell to inner grid (cathode). The only way they can do this is to form or be created out near the shell of the device.

In a simple fusor, they are created through out the volume of the device with preferential towards the inner grid region (not good). The bulk of the losses in the simplest form of the fusor are due to its high pressure which makes it a single pass device, (no recirculation of ions), and the fact that a large number of ions are created near the inner grid which makes them unable to achieve fusion energy during their infall to the inner grid. These problems are further complicated by ion neutral and neutral neutral collisions.

By placing a hot wire or thermionic emitter just off the outer shell on the inside of the device and a large second grid biased about 100-200 volts positive with respect to the heater/emitter, ions are created in this space and this is highly desirable. It is about as close as we can come in a simple design to a gunned device.

This is the Hirsch-Meeks fusor.

I suggest you check out the patent in the "files" or "links" portion of this forum.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

guest

Re: Fuel Introduction

Post by guest » Thu Sep 27, 2001 11:47 pm

By "hot wire or thermionic emitter" do people mean a wire tapped into a high voltage? I've read something about it but the language is a little beyond me. Is this heater/emitter idea similar to what was done in the University of Wisconsin? The article is on the internet at http://www.finds-space.org/He3.2000.html. They use two concentric spheres (like the cathode only much larger) with similar radii and attach them with an AC voltage and use that as an ionizer. Because the spheres are just smaller than the device, the ions are generated on the periphery of the chamber. Also, do you know much about X-ray tube heads. I have one which should work but I'm not sure if the transformer is actually located inside the tube-head or not.

bob villa

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Re: Fuel Introduction

Post by r_c_edgar » Fri Sep 28, 2001 12:09 am

Basically, a thermionic emitter is just a filament with a current running through it. The current heats up the filament, which releases electrons (I've seen it described as "boiling off" electrons). The whole filament is biases about 1-2 hundred volts more negative than the area surrounding it, so the electrons are repelled from the filament once they are free.

The electrons impact with gas atoms (in our case, Deuterium) and impart enough energy through the impact that the nuclei and electron are freed from each other. So you end up with another electron, and an ionized Deuterium nucleus.

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