Search found 161 matches

by prestonbarrows
Sat Jun 23, 2018 3:01 am
Forum: Images du Jour
Topic: Deposition within a fusor
Replies: 4
Views: 3444

Re: Deposition within a fusor

My question was, were the deposition patterns you are reffering to a 'positive' pattern (the outlines of the grid aligned with lines of the grid material deposited on the outer chamber wall) or a 'negative' pattern (isolated spots of the grid mateial aligned with the voids between the central grid o...
by prestonbarrows
Sat Jun 23, 2018 2:49 am
Forum: Images du Jour
Topic: First Plasma
Replies: 11
Views: 4483

Re: First Plasma

That vacuum chamber was one that I was just using for plasma generation. I am going to purchase a 2.75 inch conflat cross for the actual chamber with the proper conflat fittings. Vacuum systems are a 'weakest link' situation. It dosen't matter if you have a vacuum chamber from CERN and a vacuum pum...
by prestonbarrows
Sat Jun 23, 2018 2:30 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Build a HV bias meter for free.
Replies: 9
Views: 5024

Re: Build a HV bias meter for free.

Once the failure rate of an insturment approaches (inevitably in your mind) unity, the effective accuracy (for all previous times) approaches zero.
by prestonbarrows
Tue May 22, 2018 4:20 am
Forum: Images du Jour
Topic: Deposition within a fusor
Replies: 4
Views: 3444

Re: Deposition within a fusor

Have you fooled around with srim for these materials, energies and currents? Do those sims match up with what you see?

Are you saying you saw a 'positive' grid pattern on the walls (lines) or a 'negative' one (spots)?
by prestonbarrows
Tue May 22, 2018 3:46 am
Forum: Vacuum Technology (& FAQs)
Topic: Vacuum Pump Issues
Replies: 8
Views: 3535

Re: Vacuum Pump Issues

A bit hard to tell from your pic but the oil through viewport should look clear and translucent(like maple syrup) not milky or opaque (like caramel). Opaque means air bubble or water emulsion. If it gets bad, only solution is to flush the oil. You should do initial tests with the pump deadheaded to ...
by prestonbarrows
Tue May 22, 2018 3:07 am
Forum: Images du Jour
Topic: First Plasma
Replies: 11
Views: 4483

Re: First Plasma

What kind of vacuum gauge were you using before it broke? What makes you think the gauge is broken? What makes you think the gauge is leaking oil into the vacuum?

What type of pump are you using?
by prestonbarrows
Sat May 19, 2018 4:17 am
Forum: Images du Jour
Topic: First Plasma
Replies: 11
Views: 4483

Re: First Plasma

The fact that there is a visable glow discharge around your electrode shows you are making a plasma. The visable light comes from free ions and free electrons (a plasma) relaxing back into a neutral gas and spitting out the excess energy as a photon. ~300 microns or 0.3 Torr, is a very high pressure...
by prestonbarrows
Sat May 19, 2018 3:41 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Reusability of Swagelok
Replies: 14
Views: 6416

Re: Reusability of Swagelok

Standard "Swagelok" fittings (the crimp ferrules) are really only meant for one or two uses with every day fluids like, say, a refrigerator condensor. They can be pressed into use for vacuum, but expect to hit problems if retightened more then once or twice. Maximum performance in the 1E-5 ish Torr ...
by prestonbarrows
Sat May 19, 2018 3:28 am
Forum: Vacuum Technology (& FAQs)
Topic: Turbopump Screen
Replies: 4
Views: 2342

Re: Turbopump Screen

Turbo inlet screens are typically just loosly retained by the conflat or ISO gasket on the inlet port. That is, they won't be positivly fixed until you install the pump on the mating flange. Then, they should be a bit loose, but not able to grossly fall out.
by prestonbarrows
Sat May 19, 2018 2:39 am
Forum: FAQs: Fusion and Fusor Theory
Topic: FAQ - Magnetics
Replies: 1
Views: 3483

Re: FAQ - Magnetics

To add to what Richard said, modeling permanent and electromagnets is dead simple in theory. Just plug and chug through Maxwell's equations from first principles. FEMM is a great freeware 2D magnetics modeling package. http://www.femm.info/wiki/HomePage The trickiness is the mismatches between reali...