Anode layer ion source. Operation pictures

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
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Werner Engel
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Re: Anode layer ion source. Operation pictures

Post by Werner Engel » Fri Mar 20, 2015 6:12 pm

Hi Andrew!

Great that you still work on the fusor! Thanks for all your posts - great pictures and details!

What kind of "laser density probe" do you use in this case?
Interferometry, reflectometry, scattering, refractive index?

BR,
Werner

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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Sat Mar 21, 2015 2:00 pm

Hi Werner,

It's going to be a CO2 interferometer.
http://www.rtftechnologies.org/physics/ ... ometer.htm

Andrew
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Werner Engel
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Re: Anode layer ion source. Operation pictures

Post by Werner Engel » Sat Mar 21, 2015 5:04 pm

Hi Andrew!

Congratulations to your final picture (the one showing the interference pattern)!
It's an enormous amount of work doing this @10,6µm with all the special materials. The carbon-pipe is it really stiff enough? What about vibrations from the roughing pump? Or did you switch off pumping during the measurement? Did you choose the 10,6 due to absorption of the plasma to be expected at that density (plasma frequency) or to reduce vibration induced problems?? Thomson Scattering is done @1064 nm (Nd:YAG) at the Tokamak in Garching. It seems they do not care about wavelength. But other refractive index measurements try to use as large as possible wavelengths.
I just built a “normal” HeNe-Michelson to get comfortable with optics. But this will be adapted in several steps.

Attached a Picture of my Michelson and one of the Nd:YAGs in Garching.

BR,
Werner
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IMG_4433 small.jpg
IMG_4774_small.jpg

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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Tue Nov 24, 2015 4:04 am

New modifications to the anode layer ion source:

The old flat anode ring has been replaces with a conical anode ring (6.6 degree inward) for better beam focusing. this should have the focal point about 3" in front of the face of the source, right at the focal point of the fusor. In reality there still is the effect from space charge repelling the beam so it doesn't focus to a point, though the beam is considerably better defined with a tighter focus.

The NdFeB magnet has also been replaced with a SmCo magnet for higher temperature operation(up to 300C instead of 80C for the NdFeB)

Stainless Steel Belleville Disc Spring (mcmaster 9713K437) (6.6 degree inward angle) and jig to bore to correct ID
IMG_20151123_160242765_HDRa.jpg
New and old anode rings
SAM_4575a.jpg
SmCo magnet installed
SAM_4576a.jpg
Modified injector re-assembled
SAM_4578a.jpg
Ion beam
SAM_4581a.jpg
SAM_4584a.jpg
SAM_4582a.jpg
Video of operation
https://www.youtube.com/watch?v=DbfmR5t ... e=youtu.be
https://www.youtube.com/watch?v=UDQ1BAH ... e=youtu.be
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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Thu Nov 26, 2015 4:21 am

Additional pole pieces have been tested to determine the effect of the magnetic field position on beam focusing
Numbers 1,2,and 3 from left, pole piece 1 was the one used in all previous tests
The version 1 has a 1/8" step of 0.5" dia, then a 1/16" step of 0.625" dia, then a 45degree taper over 1/16"
The version 2 has a1/16" step of 0.5" dia, then a 1/16" step of 0.58" dia, then a 15degree taper over 1/16"
The version 3 has a 1/16" step of 0.5" dia, then a 15degree taper over 0.1875"
SAM_4611a.jpg
SAM_4612a.jpg
Version 2 pole piece and plasma focus
SAM_4589a.jpg
SAM_4599a.jpg
Version 2 pole piece recessed and plasma focus
SAM_4606a.jpg
SAM_4609a.jpg
Version 3 pole piece and plasma focus
SAM_4621a.jpg
SAM_4622a.jpg
Version 3 pole piece recessed and plasma focus
SAM_4614a.jpg
SAM_4616a.jpg
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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Tue Dec 01, 2015 3:58 pm

Further pole pieces tested
Numbers 1,2,and 3 from left, pole piece 1 was the one used in all previous tests
The version 1 has a 1/8" step of 0.5" dia, then a 1/16" step of 0.625" dia, then a 45degree taper over 1/16"
The version 2 has a 1/16" step of 0.5" dia, then a 1/16" step of 0.58" dia, then a 15degree taper over 1/16"
The version 3 has a 1/16" step of 0.5" dia, then a 15degree taper over 0.1875"
The version 4 is 7.5mm long 14mm dia
The version 5 has a 1/16" step of 0.5" dia, then a 1/16" step of 0.58" dia, then a 15degree taper over 1/8"
Version 4 and 5 have a pump out groove milled in the base to vent the trapped volume inside the magnet
SAM_4651a.jpg
SAM_4652a.jpg
Version 4 pole piece and plasma focus
SAM_4653a.jpg
SAM_4659a.jpg
Version 5 pole piece and plasma focus
SAM_4660a.jpg
SAM_4662a.jpg
SAM_4663a.jpg
Version 5 is going to be the final version used to upgrade the ion sources, it seems to hold the best focus
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Steven Sesselmann
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Re: Anode layer ion source. Operation pictures

Post by Steven Sesselmann » Tue Dec 01, 2015 8:23 pm

Andrew,

Once again I commend you on your engineering skills and systematic approach to solving a problem, this work on your anode layer source would be worth writing a paper on.

It will be interesting to see if the narrower beam increases the fusion rate or efficiency.

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Wed Feb 01, 2017 11:21 pm

Performance curves for the anode layer ion source
ALIS_curves.jpg
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Re: Anode layer ion source. Operation pictures

Post by Andrew Seltzman » Thu Feb 02, 2017 5:45 am

I finally got around to converting all the drawing for the ion source from my old cad program (KeyCad, made in 1992) into a modern program (Autodesk Inventor) and made some 3D models:
side.jpg
half-cut2.jpg
half-cut1.jpg
Anode-layer-ion-source-MF.jpg
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Werner Engel
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Re: Anode layer ion source. Operation pictures

Post by Werner Engel » Thu Feb 02, 2017 5:52 pm

Did you allready try to focus the beam? Maybe with a Wehnelt cylinder or an einzellens?
Or is this even planned?
Higher luminosity would be nice - I think.

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