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Registered Member #1521
Joined: Thu Jun 05 2008, 10:46AM
Location: Hungary
Posts: 128
Actually you need some series resistors with the power supply to limit the shortcircuit current, which flows through the output spark gap, when the marx fires. I didn't used any, and my transformer buzzed very loud.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
I might use a HV relay to disconnect the Marx from the power supply when it fires. Or I might just use a triggered spark gap, which is infinitely easier to build
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
Finally started building this beast. I wound 15 charging inductors today, each 6" long and ~200 turns of 22 AWG wire on a 1" OD PVC former. The calculated inductance is around 180 uH per inductor. I'm beginning to worry that 6" is not enough to hold off the stage voltage
Registered Member #1521
Joined: Thu Jun 05 2008, 10:46AM
Location: Hungary
Posts: 128
bwang wrote ...
Finally started building this beast. I wound 15 charging inductors today, each 6" long and ~200 turns of 22 AWG wire on a 1" OD PVC former. The calculated inductance is around 180 uH per inductor. I'm beginning to worry that 6" is not enough to hold off the stage voltage
22AWG, why? It's totally unnecessary to use so thick wire. I used 0,3mm wire (29AWG), and I think a thinner wire can be used too.
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
omegalabs wrote ...
22AWG, why? It's totally unnecessary to use so thick wire. I used 0,3mm wire (29AWG), and I think a thinner wire can be used too.
Most likely to get the 6" physical length without an excessive number of windings. Surface tracking is a bitch, and 10kV can easily track 1" under the right conditions. I would not trust those with more than 50kV unless you have some fancy isolated connectors.
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
Yes, the 22 AWG wire is so I don't have to wind 500+ turns on each coil, which would be a serious pain in the ass. I'm going to need to work a bit to get 80KV to work with these inductors, I guess. Would copiously varnishing the coils help reduce surface tracking?
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
Remember that your inductors are going to see the full capacitor charging voltage, and that the voltage seen between each winding is [charging voltage]/[number of windings]. Magnet wire has had different results for different people, with some people testing it to kV, but it is not commercially rated very high. I don't think you specified the type of wire you used, besides 22 AWG, but if you wanted to make it longer without extra windings and have good insulation, I think you should have chosen a wire with thick plastic insulation. I know this is a bad time to mention that, sorry, but I thought you were planning on using larger inductors than 6"...
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
The wire is this: I might wind another set of inductors and series two per stage. The voltage between adjacent windings is 400V with my current inductors...a bit too high for my liking
Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
This project is not dead yet! I have all of the inductors done...over a mile of 22AWG wire. Next step is to varnish the coils and do some mechanical assembly. Charging has changed from an X-ray transformer to Steve Ward's CCPS driving a 4-stage CW.
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1.2 MV Marx Generator
