egun materials

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
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fisikdan
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egun materials

Post by fisikdan »

any one knows what is the normal material for the base of cathode and also anode and grid for a thermionic electron gun?
many thanks,
3l
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Re: egun materials

Post by 3l »

Hi:

For hot gun sources:

The materials for the grid is usually tungsten but can be made of other platinum alloys (read expensive).
The bodies of the guns can be ss,tungsten ,molybendum,
rhenium, vanadium any high tem material.

Happy Fusing!
Larry Leins
Fusor Tech
fisikdan
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Re: egun materials

Post by fisikdan »

Larry, why we dont use copper for non-emitter bodies like anode, or grid? i am gonig to use mixed oxides for the cathode material, but for the bodies of anode, grid and cathode ive been confused.
3l
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Re: egun materials

Post by 3l »

Hi:

Copper has undesirable physical characteristics for a vacuum ion/electron source.
It has a relatively low melting point and vaporises easily.
Fusors get hot and even Anodes have sputtering due to electron bombardment.
Daily vacuum operations are complicated by coppers active desire to corrode. It holds water like a sponge on it surface if it's oxidized making for longer pump down.
It sputters and leaves copper plate on all surfaces during a run.
Fowls electrical connectors and viewports after some operation time. It is ok for demo or short time use but for high power it leaves much to be desired compared to ss.

Happy Fusing!
Larry Leins
Fusor Tech
fisikdan
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Re: egun materials

Post by fisikdan »

Hello,
as the latest question in my electron gun design, im gona test the trajectory of electrons between cathode and anode before manufacturing the egun, any body knows any code for that? ive been tried for EGUN of SLAC , but couldnt find a downloadable version of it in the web. I will send the pdf dtail of my design later,
many thanks for any suggestion for the software... i am just waiting for it..
DaveC
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Re: egun materials

Post by DaveC »

EGun is a commercial program and sells for around $3000. (About half that if you are an active student or Faculty) Probably why you can't find a current version. Also, it is 2D.

Dave Cooper
JohnCuthbert
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Re: egun materials

Post by JohnCuthbert »

Can I just point out that copper doesn't oxidise in low pressure hydrogen (Or D2). Of course this doesn't stop it melting and sputtering.
seadat_mis
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Re: egun materials

Post by seadat_mis »

I think the best material for the body is SS. for the grid, tungstan is fine. for the anode as well SS makes a better performance for the electron gun.

Seadat Varnaseri
3l
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Re: egun materials

Post by 3l »

Hi John:

It's not the problem when copper is in vacuum but what happens when you have to open your chamber for upgrade or repair.
I have nickel plated all copper feedtroughs to prevent this problem.

Happy Fusoring!
Larry Leins
Fusor Tech
DaveC
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Re: egun materials

Post by DaveC »

I think you will have sputtering with any metal, just a matter of extent. After all, all the ion has to have is sufficient energy to overcome VanderWaal forces, and metal atoms are free. Electrons just need a boot with more energy than the vacuum level work function (couple eV) and they're out and about.

With those10kEV or higher electrons and ions, there's enough energy to do....even fusion. Ya sure you betcha.

Dave Cooper
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