FAQ - Ion gun? What? Why?

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Richard Hull
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FAQ - Ion gun? What? Why?

Post by Richard Hull » Fri Oct 22, 2010 8:14 pm

This is the first FAQ in this forum and I will make it general to the Newbie.

The whole operation of the fusor in making fusion occur depends on or getting our hands on a whole bunch of positive, fusion fuel ions. (deuterons)

In the normal fusor these are created through field emission ionization where we force conduction through the gas via a huge potential difference applied between two electrodes. (The shell and the inner grid) This causes a break down of the gas and the insuing current and gradient ionizes the gas to a form of weak plasma. The plasma ideally consists of electrons and deuterons. This process is somewhat willy-nilly and unorganized, but it allows us to do fusion all over the volume of the fusor. It is a very confused fusion, but fusion, nonetheless.

A far more scientific and proper approach, albeit more expensive and difficult to achieve, is to make the deuterons enmass in a separate area and inject them directly into the fusor. The deuterons can then be released at the ideal location, near the outer positively charged shell, and aimed like in a gun to fire at each other and the inner negative accelerator grid. In this manner we seek to increase the fusion yield by "controlling" the process in a manner far better than in the simple fusor.

We need an "ion gun" to carry out the above controlled process.

The ion gun can take on many forms, but usually involves a heated filament in an enclosed cylinder surrounded by a ring magnet, between the filament and an extractor electrode. The filament supplies electrons and deuterium gas is admitted at very low pressure and a heavy, conductive arc is initiated creating a lot of deuterons eager to pass through a microscopic hole in the extractor electrode. This ion gun cylinder is attached to the outer shell of the fusor and the deuterons are launched into it in a pencil like beam towards the accelerator grid in the fusor.

Simple fusors can readily be adapted to use ion guns. The original Farnsworth devices of the 1960's used ion guns. As many as 8 ion guns can be used, but 4 is the norm, while just one or two would be helpful.

Ion guns are by no means limited to the above type of construction or excitation. To this end this forum is placed here. Few amateurs here or anywhere have used ion guns in their fusors, but there is hope that using these guns will help improve the performance of the fusor.

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.

Max O Donoghue
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Re: FAQ - Ion gun? What? Why?

Post by Max O Donoghue » Tue Apr 11, 2017 8:04 am

What is the optimum filament diameter, and roughly how much current is required to heat it. I am assuming the material is tungsten.

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