ChipSHOUTER output voltage decreases when generating three or four pulses



I have been doing some performance testing with the ChipSHOUTER device using the 4 mm CW tip and I have run across a behaviour I didn’t expect.

When using the programmable pattern generator to generate three (3) or four (4) consecutive pulses that have a 80 ns width and a 500 ns deadtime (delay) spacing between each pulse, I noticed that when the output capacitor band voltage is set to >= 300 V, the first two pulses seem to be within +/- 10% of the maximum value of the first pulse. But, the third (and fourth) pulses start to decline as the voltage is increased up to 500 V. At the 500 V setting, the third (and fourth) pulse is down to less than half of the voltage of the first pulse.

I’m already meeting the restrictions listed in the “Inserted Pulse Characteristics” table on page 19 of the users manual:
Minimum consecutive pulse spacing (for 4 mm tip @ 500 V):

  • 3 pulses: 175 ns
  • 4 pulses: 250 ns

Given that I would want all the pulses to generate the same voltage, are there any restrictions that need to be met in order to generate three (or four) pulses that all have the same output voltage?

Any feedback would be appreciated.

  • Brad