I'm somewhat stuck trying to build the electrical system for a discharge lamp, and could use some advice. It's an experimental sliding spark lamp for laboratory use. It's basically a pulsed discharge lamp, and I'd like to feed it with ~1kV pulses. Pulse width should be around 20 us long, and pulse frequency should be around 200 Hz.
My initial idea is shown in the attached schematic. The Control signal is connected to a simple 555 timer circuit that produces the pulses as described above. The SCR is rated for 1600V and 105A continuous; the capacitor is rated for 2kV. The high voltage power supply can only output negative voltage (other terminal is connected to the chassis ground).
The problem is, the discharge doesn't stop at the end of each pulse. I was hoping each pulse would terminate by itself as the capacitor is discharged, and the voltage dropped to a point where the lamp would no longer conduct. However it seems the power supply can maintain a high enough current and voltage so the lamp and SCR never shut down.
If I connect another SCR in parallel with the lamp+SCR, and trigger it after each pulse, would that be a reliable way to shut off the SCR connected to the lamp? Or would it be better to have some sort of switch (solid-state relay?) between the capacitor and power supply and open this during discharge? Any other options? Or are more major changes called for?
My initial idea is shown in the attached schematic. The Control signal is connected to a simple 555 timer circuit that produces the pulses as described above. The SCR is rated for 1600V and 105A continuous; the capacitor is rated for 2kV. The high voltage power supply can only output negative voltage (other terminal is connected to the chassis ground).
The problem is, the discharge doesn't stop at the end of each pulse. I was hoping each pulse would terminate by itself as the capacitor is discharged, and the voltage dropped to a point where the lamp would no longer conduct. However it seems the power supply can maintain a high enough current and voltage so the lamp and SCR never shut down.
If I connect another SCR in parallel with the lamp+SCR, and trigger it after each pulse, would that be a reliable way to shut off the SCR connected to the lamp? Or would it be better to have some sort of switch (solid-state relay?) between the capacitor and power supply and open this during discharge? Any other options? Or are more major changes called for?
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