Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA-9mA

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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Steven Sesselmann » Tue Aug 23, 2016 12:15 am

Andrew,

Did I understand this correctly, the cap was initially not brazed to the cooled grid and so became heated from the ion bombardment, so you have now brazed it to the grid so it now stays cool?

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: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Seltzman » Tue Aug 23, 2016 1:05 am

That's correct. The previous version had a molybdenum cap for shielding the lip of the ceramic. The cooling lines just stuck through, making electrical contact, but without making good thermal contact. The new version has a brazed stainless cap.
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Richard Hull » Tue Aug 23, 2016 3:43 am

Thanks for the info. My shell has no ion sources pointing at one another across the sphere. Those beams on delecate parts in the chamber would be a bad thing.
So much for taking the time to critically align stuff during assembly.

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.
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Seltzman » Tue Aug 23, 2016 7:05 pm

The beams seem very well aligned, the fact that they are hitting near the ion injector ports is due to the electrostatic lensing effect from the grid. The grid consists of 3 rings, and while it resembles a spherical source at a distance, nearer to the grid the discrete effects of the grid rings are noticeable. An ion beam fired directly radially inward at +-45 degrees to the midplane of the vacuum vessel will pass through the grid and bend towards the midplane. When exiting the grid it will be at an angle nearer to horizontal and will strike the shell about halfway between the midplane and the opposing injector port.
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Seltzman » Sun Feb 26, 2017 7:05 am

I've been working on converting my older CAD files on the fusor into autodesk inventor, here's what I have so far
core1high.jpg


Cross sectional view
core3high.jpg


Grid Detail
grid.jpg


Grid insulator box detail showing cooling lines
grid_box.jpg


Detail of machined macor grid insulator
grid_tip.jpg

grid_tip2.jpg

grid2.jpg
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Richard Hull » Sun Feb 26, 2017 9:34 am

Nice CAD work. Very professional. Fabulous images of what the finished product will resemble. Boy, times, they do change.

I took two classes in engineering drafting while in college in the mid-sixties. We joked about the drafting requirements, saying that should we fail as electronics engineers, we could always find work with International Havester designing self-propelled manure spreaders.

I bought the drafting table and a super nice set of drafting instruments and used them into the early 70's for my own work and pleasure. I still pull them out on occasion, but tend to use simple Computer drafting programs for mechanical stuff and schematic programs for electronic circuit printouts. I have never considered CAD, as I can doodle out a 3-D mechanical impression and see issues develop on that front. Without free access to CAM, I always felt CAD, by itself, a bit over blown. CAD-CAM need to be fully wed and implemented together. My thoughts.

As the brain ossifies, I currently only attempt to learn that which is supremely valuable immediately which is free of any cost. As I am retired, the only new stuff I need to know is that which presents itself in the press of advancing my own personal efforts. I don't have to impress any one person or employer any more. I have a lifetime accumulation of hard won knowledge, about 60% of which is useful now only for campfire stories about how it was in the "old days". This sort of specific, focused knowledge and its application, which the young folks here strive for now, will be part of their campfire story collection in later life, as well. There will always and forever be "this new thing" leaving the bulk of your past efforts and hard won experience, a relic on the trash pile of what was once the cat's pajamas.

All that past effort in life, as you advanced, served to put bread on the table, pay for the car, etc. However, just as the bread ultimately ended up in the sewer system as consumed waste product and the car, in the junk yard, having ferried the family around so valiently, so hot, current, specific skill sets in focused endevors will also fade from being of any real value in future.

This is why I can see the sage, yet sad, Yogi Berra quote in my closing salutation as truly humorous on many levels.

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.
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Robinson » Mon Feb 27, 2017 6:56 pm

Glad to see you pushing into some newer CAD software Andrew. Nice attention to detail. I keep trying to reinforce the usefulness and application of CAD here. With your level of past attention to detail, I know I don't need to try to convince you. I know it can be a daunting task to model everything but very rewarding in the end. We're now pushing into the 1000's of hours on our current model. I'd be happy to talk CAD with you. I'm sure we both have some tips and tricks we can share. Keep it up and as always, I continue to look forward to your progress.
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Robinson » Mon Feb 27, 2017 7:24 pm

Andrew,

You may be particularly interested in the thermal and flow characteristics we're modeling currently off your original design. Note the continuous feature via 3D sketches to enable the flow and thermal simulations of the grid. This was an early (and incomplete) 3D test and unfortunately I'm not at the office currently so I don't have our updated models or data to share at the moment, but like I said, send me a message sometime. We're investigating heavily into this area and building on your previous success. I would love to share data between teams.

Capture.PNG
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Robinson » Sat Mar 11, 2017 10:29 pm

Hey Andrew,

I fired off a few emails to you, but I'm not sure if I have the correct email address. I wont post it here in plain text due to crawlers but are you still at the university/using that email address? Looking forward to hearing back from you.

Cheers,
Andrew
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Re: Mark3 operation 3e-4 torr / quad ion source @ -40kV, 1mA

Postby Andrew Seltzman » Sun Mar 12, 2017 8:29 pm

I'm here(same address), I sent you a response via email.
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