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Registered Member #2063
Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352
Came across this instructables few days ago too bad I fried all my flyback transformers, my only source of HV is a 10kV 20mA oil ignition transformer, which is AC btw. would the fridge pump stall if its left on for too long? the fridge pump seems too weak to pump a proper vacuum because it takes like 50 attemps to get an arc started. but once its started, it looks AWESOME
Registered Member #3271
Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159
looks nice. I would strongly suggest a sheet of plexi on top as protection. Local heating could cause the glass to shatter, implode and send shrads all over.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Nice project. Heed safety warnings, at minimum wear face/eye protection.
Can you subject the plasma arc to an AC magnetic field, to see if the beam will display any wavelike deflection lengthwise or at the end surface? You could try regulating the beam current, with a Variac on the primary, as a weaker current will deflect beam further for a given field.
If you do get the deflection to work, and have an audio oscillator and an amplifier, you could try Lissajous patterns.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
An excellent experiment!
If you backfill your glass vessel with cheap helium balloon gas, and then pump it down again, you will find the mean free path of the electrons will be very much longer.
Registered Member #2063
Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352
yea it does get quite hot to touch after a few minutes with the HV on. how strong of a vacuum can a fridge pump suck? on the instructables video, theres glowing plasma around the bottle, but mine only have an arc. is it because theres still air inside the bottle?
yesterday i made another gas discharge tube from a thick test tube, can't wait to fill it with helium and see it glow.
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
If you want to continue further it would be worth investing in a better vacuum pump. Fridge pumps are OK, but not great. If you want to get down to e-beam levels you are going to need both a good mechanical pump and a diffusion pump (or something similar).
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
haxor5354 wrote ...
on the instructables video, theres glowing plasma around the bottle, but mine only have an arc. is it because theres still air inside the bottle?
Yes, you are correct.
An arc can only occur in a gas. You could try googling 'Paschen's law' for further information.
As PM has suggested, backfilling with helium (or cheap balloon gas, which isn't pure helium) should give better results at the pressure your pump achieves.
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wine bottle CRT/gas discharge tube
