Search found 211 matches

by Jeroen Vriesman
Sun Sep 11, 2016 4:36 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: My Manhattan Project...
Replies: 6
Views: 3377

Re: My Manhattan Project...

Sven, we got our 350W RF power supply from a vacuum equipment surplus seller. With the matching network. So we took the easy road :) did cost some money. The goal of a matching network is to transform the impedance of the load (the plasma) to about 50 ohm load on the coax cable. That is simple with ...
by Jeroen Vriesman
Wed Sep 07, 2016 9:21 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: My Manhattan Project...
Replies: 6
Views: 3377

Re: My Manhattan Project...

picture of our home-build plasma cleaning, bell jar with coil, 13.56MHz 350W
by Jeroen Vriesman
Wed Sep 07, 2016 9:05 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: Shining UV-C on a Tungsten wire to increase emittance?
Replies: 5
Views: 3312

Re: Shining UV-C on a Tungsten wire to increase emittance?

Sven, ...a Tungsten filament that is untreated (not treated with Barium or Strontium)... I think you are mixing the idea of a treated tungsten filament (thoriated and/or carburized) for direct emission with an indirectly heated cathode. An indirectly heated cathode (which can be heated with any sour...
by Jeroen Vriesman
Thu Sep 01, 2016 2:44 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: A question on heated filaments?
Replies: 6
Views: 2900

Re: A question on heated filaments?

Dan, none of the oxide coated filaments survive atmospheric conditions, they react with the water in the air, forming hydroxides. Usually such a "indirectly heated" oxide-coated filament is stored with a carbonate coating, and then activated in vacuum by heating it, the carbonate releases CO2 and be...
by Jeroen Vriesman
Tue Aug 30, 2016 9:19 am
Forum: Images du Jour
Topic: radioactive food?
Replies: 3
Views: 1946

Re: radioactive food?

funny!

but really... there was a time people thought that radium was some kind of magic medicine, radioactive chocolate, even radioactive toothpaste!

http://mentalfloss.com/article/12732/9- ... tood-risks
by Jeroen Vriesman
Sun Jul 31, 2016 5:39 pm
Forum: Vacuum Technology (& FAQs)
Topic: making thoriated tungsten filaments
Replies: 0
Views: 1127

making thoriated tungsten filaments

First step towards carburasation of thoriated tungsten filaments is making the filament. We started with a mold of graphite, in which we put two Ti-5Al-2.5Sn wires and some lead-glass powder. We heated the graphite with an induction heater, the coil is air-cooled with a compressor. Next, we spot-wel...
by Jeroen Vriesman
Thu Jul 28, 2016 9:14 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electron gun- what's wrong here?
Replies: 54
Views: 35314

Re: Electron gun- what's wrong here?

Hi Steven, in your reference you seem to state that potential is limited because relative velocity is limited, however, the energy associated with relative velocity is not limited, it goes to infinity near the speed of light, so the potential is not limited. You are using the special theory of relat...
by Jeroen Vriesman
Thu Jul 28, 2016 8:12 am
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electron gun- what's wrong here?
Replies: 54
Views: 35314

Re: Electron gun- what's wrong here?

Hi david, But with Gauss' Law, wouldn't there be zero E field inside the nipple and the spherical chamber to pull the electrons to the walls? Yes, but only if there are no objects in the chamber with some other potential. If you have something inside your chamber at a potential U, and the chamber is...
by Jeroen Vriesman
Wed Jul 27, 2016 1:17 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electron gun- what's wrong here?
Replies: 54
Views: 35314

Re: Electron gun- what's wrong here?

Hi Steven, I just tried to answer the original question about an electron source, not the ion source related stuff. The filament-anode ring-target setup is comparable to a ordinary triode (cathode-grid-anode) with well-known behaviour. Making the grid in a triode positive a little bit gives more ano...
by Jeroen Vriesman
Wed Jul 27, 2016 12:05 pm
Forum: Ion Gun Design and Construction (& FAQs)
Topic: Electron gun- what's wrong here?
Replies: 54
Views: 35314

Re: Electron gun- what's wrong here?

I don't really get the idea of a high negative bias on the filament. Indeed, it would accelerate the electrons more, but imho this might be the problem, not the solution, and the negative power supply would just be used for running current through the diode (filament + anode ring = diode). If you ta...