Hello!
I have a problem...
I have a 450v capacitor charged to 320v, which I have to discharge across two electrodes inside a vacuum chamber. The vacuum chamber has a pressure low enough to allow plasmas to generate at about 1000v or so.
Ive gone through several attempts to solve this:
Using a HV transformer outputting 2kV to create an arc, and discharge the capacitors through said arc. (Plasma is conductive, so it shorts out the electrodes and discharges the capacitors)
The idea was to use a couple of microwave oven diodes to prevent the 2kV from popping the 450v caps, and it worked. However, upon increasing the size of the capacitor, (from 1000uF to 5000uF) it would still work, albeit destroying the diode in the process.
For this reason I tried using an old flyback to generate the spark. The flyback is isolated from the capacitor by two capacitors which dont allow DC through, and the capacitors are protected by two inductors which filter out the 25kHz from the flyback.
This again, worked, however, since the inductors have arround 35ohms of resistance each, it they dont allow the capacitor bank to discharge with a spark. (Otherwise the resistance of the path to the electrodes is a bit less than 1ohm).
The problem is, I need a method of discharging the 320v as fast as possibe, inside a vacuum chamber.
I was thinking of three possible solutions:
1 - Substituting the large inductors for smaller 10mH inductors which only have 40 milliohms of resistance each, and use the flyback method,
2 - Since the capacitor bank is composed of 5, 450v 1000uF caps, I could rig them in series to get a 2700v 160uF capacitor bank, and then charge that with the HV transformer to 2kV. (Which should be able to discharge on its own, without the need for an additional spark)
3 - Using the HV transformer outputting 2kV and relying on the fact that the capacitors can withstand 450v, and that the 2kV are only applied for arround 20ms. (The capacitors will not be in continuous operation, and they will probably only see about 50 2kV pulses total in their entire life. Maybe even less)
What do you guys think? Any ideas?
I have a problem...
I have a 450v capacitor charged to 320v, which I have to discharge across two electrodes inside a vacuum chamber. The vacuum chamber has a pressure low enough to allow plasmas to generate at about 1000v or so.
Ive gone through several attempts to solve this:
Using a HV transformer outputting 2kV to create an arc, and discharge the capacitors through said arc. (Plasma is conductive, so it shorts out the electrodes and discharges the capacitors)
The idea was to use a couple of microwave oven diodes to prevent the 2kV from popping the 450v caps, and it worked. However, upon increasing the size of the capacitor, (from 1000uF to 5000uF) it would still work, albeit destroying the diode in the process.
For this reason I tried using an old flyback to generate the spark. The flyback is isolated from the capacitor by two capacitors which dont allow DC through, and the capacitors are protected by two inductors which filter out the 25kHz from the flyback.
This again, worked, however, since the inductors have arround 35ohms of resistance each, it they dont allow the capacitor bank to discharge with a spark. (Otherwise the resistance of the path to the electrodes is a bit less than 1ohm).
The problem is, I need a method of discharging the 320v as fast as possibe, inside a vacuum chamber.
I was thinking of three possible solutions:
1 - Substituting the large inductors for smaller 10mH inductors which only have 40 milliohms of resistance each, and use the flyback method,
2 - Since the capacitor bank is composed of 5, 450v 1000uF caps, I could rig them in series to get a 2700v 160uF capacitor bank, and then charge that with the HV transformer to 2kV. (Which should be able to discharge on its own, without the need for an additional spark)
3 - Using the HV transformer outputting 2kV and relying on the fact that the capacitors can withstand 450v, and that the 2kV are only applied for arround 20ms. (The capacitors will not be in continuous operation, and they will probably only see about 50 2kV pulses total in their entire life. Maybe even less)
What do you guys think? Any ideas?