Magnetron Ion Gun

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
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Steven Sesselmann
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Re: Magnetron Ion Gun

Post by Steven Sesselmann » Wed Feb 24, 2010 10:52 pm


Not sure which diagram you are referring to, but to clarify the Starfire ion source merely uses the filament and power supply "from" a commercial magnetron, as it happens to be the perfect shape and very robust. So not a magnetron per se.

Steven - Gamma Spectrometry Systems - Various papers and patents on RG

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Chris Bradley
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Re: Magnetron Ion Gun

Post by Chris Bradley » Wed Feb 24, 2010 10:55 pm

It was a post under (and in respect of) Ethan's, with "magnetron" printed on his image.

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Carl Willis
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Re: Magnetron Ion Gun

Post by Carl Willis » Thu Feb 25, 2010 12:07 am


"Figure 2A" represents the standard circuit of a household microwave oven.

The magnetron tube is depicted as a high-vacuum diode, of which it is a variant.

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Re: Magnetron Ion Gun

Post by EthanH719 » Thu Feb 25, 2010 12:58 am

Doug, you say that the ideal voltage is 70-150v? Doesn't a magnetron filament transformer only produce 3-6v (with the 2kv bias)? Yes, I do have a variac to limit current, might also be a good idea to stick a light bulb in there. I found some barium carbonate laying around, so I'll probably just use that for the coating. Also, will the fact that my vacuum chamber is charged to 15kv during operation effect the ion gun? I had to do this so I could get 30kv total across the chamber and inner grid without using a ton of current.

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Doug Coulter
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Re: Magnetron Ion Gun

Post by Doug Coulter » Thu Feb 25, 2010 4:09 am

That 70-100v number is for the electron velocity, not the filament heating voltage. You can try more or less, Steven seems to be saying he's using the full couple kV for this.

You'd have to ask Steven about that other question, or fill me in with a bunch more detail for me to answer. If I understand right, Steven's design uses the tank itself as the anode for the electrons, so this would make some problems perhaps....

I'm avoiding chambers that are off ground for now, but I do plan to do some interesting things in quartz tubing (pumped by the same system) with split supplies so I can use less voltage from ground on either end (which what I think you meant by "current" -- very much not the same thing, think of voltage as pressure and current as flow in a plumbing analogy and you're close).
Why guess when you can know? Measure!

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Re: Magnetron Ion Gun

Post by Starfire » Thu Feb 25, 2010 11:47 am

The Starfure uses a Tungsten ring as the anode - it is swetted to the body. It is shown in photo 2


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