Search found 15 matches

by Mark Kimball
Mon Jun 04, 2018 12:49 am
Forum: Vacuum Technology (& FAQs)
Topic: Foreline pump base pressure degraded
Replies: 10
Views: 4613

Re: Foreline pump base pressure degraded

At work we had a nice gold sputtering system for preparing samples for SEM examination. It used a small 2-stage mechanical pump to evacuate the chamber. It didn't take long for the pump oil to absorb a _lot_ of water (this was in Oregon, infamous for its damp weather). Symptoms included extended pum...
by Mark Kimball
Thu May 31, 2018 6:54 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: Plasma focus/Z pinch as an amateur fusion approach
Replies: 7
Views: 6277

Re: Plasma focus/Z pinch as an amateur fusion approach

The paper Dan referenced now appears to be behind a paywall. I did find a paper here -- https://www.plasmafocus.net/IPFS/associ ... 202010.PDF that likely references a similar (if not THE) design.
by Mark Kimball
Tue May 29, 2018 11:00 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 61
Views: 39407

Re: lab electromagnet from scratch

Chris,

Wow, you really got all over that one! It is good to know that FEMM does a pretty good job of simulating electromagnets. Hopefully it's as good with NdFeB magnets because that's what I'm interested in.

-Mark
by Mark Kimball
Mon May 28, 2018 9:18 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 61
Views: 39407

Re: lab electromagnet from scratch

If you are not already using it, I have found FEMM's scripting capability (via LUA) to be useful for playing with different magnet configurations. It can speed things up quite a bit compared to manually setting dimensions of your parts (or coil currents etc.). It can take a little time to write func...
by Mark Kimball
Sat May 26, 2018 5:27 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: TIG welding tubing and flanges with an automated fixture
Replies: 8
Views: 4656

Re: TIG welding tubing and flanges with an automated fixture

The link you included in your OP indicates that the base metals are joined with no filler metal. I didn't recognize any facility in your setup for feeding in filler metal. Am I correct in concluding that you are NOT doing so?

Mark
by Mark Kimball
Sat Jun 24, 2017 10:22 pm
Forum: Vacuum Technology (& FAQs)
Topic: Source for KF25 nipples
Replies: 10
Views: 3097

Re: Source for KF25 nipples

30% H2O2, once it's got something to destabilize it, decomposes in an exothermic reaction. Even 50mL in a beaker is enough to experience thermal runaway -- right up to the boiling point. Boiling peroxide, mmm. Anyone using this concentration or higher should know what they''re doing, and NEVER retur...
by Mark Kimball
Sat Jun 17, 2017 8:43 pm
Forum: Vacuum Technology (& FAQs)
Topic: Source for KF25 nipples
Replies: 10
Views: 3097

Re: Source for KF25 nipples

A PFIB! Very nice indeed. I have heard of folks using different gasses like neon and helium. If the tool can focus He+ maybe it could focus D+. Not sure how many neutrons you'd get -- IIRC PFIB beam currents max out at 20uA or less. Doesn't sound like a lot until you consider the current density at ...
by Mark Kimball
Sat Jun 17, 2017 4:54 pm
Forum: Vacuum Technology (& FAQs)
Topic: Source for KF25 nipples
Replies: 10
Views: 3097

Re: Source for KF25 nipples

Hi Jerry,

I think I know the gentleman at PSU as well. Tony, right? He worked in our lab for a short time. We also have used his services at PSU -- TEM work for the most part.

Mark
by Mark Kimball
Sat Jun 17, 2017 4:49 pm
Forum: Vacuum Technology (& FAQs)
Topic: Source for KF25 nipples
Replies: 10
Views: 3097

Re: Source for KF25 nipples

It is true that many carbonyls are extremely toxic. W(CO)6 is a solid at RT and has relatively low vapor pressure so it's not the baddest. The FIB system performs a very thorough purge before venting so it's pretty safe. In use the W(CO)6 pops the chamber pressure up to about 3E-5 torr (thank goodne...