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can't make a "fusor" with a refrigerator compressor

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radhoo

Thu Jan 06 2011, 11:14PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

I had to try it:

A Flask + Compressor + My 50KV supply + Badly shaped concentric electrodes - deuterium = 2 hours wasted.

Proud Mary

Fri Jan 07 2011, 12:41AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

It is possible to generate abundant soft X-rays in Grimm-type glow discharge devices at relatively high pressures and relatively low voltages. For example only, say 0.25 Torr/2kV using an aluminium thin film shoot-through target and cheap helium balloon fill gas, but both the source and the detector must be in the same evacuated space, as the strong Al KÎ± rays are stopped by even a sheet of paper.

Pressures suitable for Grimm discharge operation are readily achieved with an ordinary two-stage rotary air conditioning pump, but I don't know enough about refrigerator pumps to say how useful they might be.

There is a 'fusor' flunkies forum for all that sort of thing, Quixotic characters forever trying to get a quart out of a pint pot, as I'm sure you know.

Ash Small

Fri Jan 07 2011, 01:41AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Proud Mary, actually the 'official' view on that site is that getting a quart out of a pint pot is impossible. Let's wait for ITER to prove them wrong.

EDIT: You'll need a diff pump as well.(or a turbo)

radhoo

Fri Jan 07 2011, 12:54PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

as I said, I had to try it. Now I can put that pump somewhere else and save some space.

Mark-H

Fri Jan 07 2011, 01:51PM

Registered Member #607 Joined: Tue Mar 27 2007, 10:39AM
Location:
Posts: 64

I may be wrong about this, but your psu may be a bit weak current wise... (Are you using the flyback in the background?)
I used a rectified NST with my fusor (a bit low on voltage, but gave me a nice poiser.). Your current may be a bit low even though you have 50KV.

Also, it looks as though you have contamination on the electrodes, hence the purple corona.

When I had an oil leak in my pump and oil got sucked back, I had to clean everything thouroughly with nasty solvents to get the "poiser" to come back.

I never went any further than showing a "star" at Teslathons. (I think I have pictures from the 2005/6 Notts Gaussfest.)

Cheers.

Mark.

Proud Mary

Fri Jan 07 2011, 02:04PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

radhoo wrote ...

as I said, I had to try it. Now I can put that pump somewhere else and save some space.

It's better to have tried and failed, than never to have failed at all.

radhoo

Fri Jan 07 2011, 02:07PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

@Mark, I'd love to see your pics. I have no experience in this field, so I did everything without too much thought or research. I might have had a lot of contamination (mostly oil and paraffin) not only on the electrodes but also in the Flask I used. Do you think it would make sense to give it another try? I could clean everything with NaOH .

@Stella, indeed, thanks for the encouragement :)

Mark-H

Fri Jan 07 2011, 02:23PM

Registered Member #607 Joined: Tue Mar 27 2007, 10:39AM
Location:
Posts: 64

Cheers radhoo...

As I said, I'm no expert and it was some years ago I did this... But... The contamination stopped the fusor working dead in its tracks.

It's your call as to whether you carry on if it's a lot of work for you.
If it were me, I'd give it one more go. Clean everything thouroughly, especially any oily contaminants.
Then maybe look at the power supply... Tens of milliamps is better than a few.

I'll hunt out the photos. There were some taken at the Amberly Teslathon around the same year too.

Mark.

Ash Small

Fri Jan 07 2011, 03:08PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Remember the maximum vacuum your system can reach is also the point of maximum backstreaming. It is better to have some flow of gas through the system and to operate the fusor at a considerably higher pressure than the 'base' pressure of the system.

While it is possible to obtain a poisser with a two-stage vacuum pump, your pump is probably single stage. Do you know what pressure you were operating at, and what the base pressure of your system is?

Mark-H

Fri Jan 07 2011, 04:50PM

Registered Member #607 Joined: Tue Mar 27 2007, 10:39AM
Location:
Posts: 64

Ash is right about your pump...

Fridge compressors are generally twin piston reed valve pumps (imagine a 2 stroke engine with non cam operated poppet/reed valves) that have trouble opening the reeds against atmospheric pressure.
I've used them for homemade glow tubes and "Nixie types, but had trouble with them when making valves (tubes.)
I even tried using two in series and got just as bad results.

I've still got my old 2 stage "oil leaky" pump in the garage doing nothing which I'd offer to you free, but shipping would be prohibitve I think.

Cheers.

Mark.

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