15. Demonstration of a Simple 40,000 Volt Faraday Cup Modulator Concept
The demonstration model in
this picture generates a decaying 40,000 volt exponential with a 5
second cycle time. The waveforms show the decay followed by a rapid
recharge. There are multiple methods of generating an exponential
decaying voltage potential but the challenge is how to do it simply and
with low power. The solution in this case was to use a passive decay
with a precision resistors and capacitors capable of swamping the sensor
capacitance. The network is charged precisely to 40,000 volts and then
the power supply is actively shunted to allow for the precision
discharge. In the series of pictures, the upper left picture shows the
series resistor associated with the active shunt. The 4 circular
cavities each operate at 10,000 volts and houses the shunt system and
precision RC network plus the shunt drive transformer (orange circles on
the outside of each housing). One critical element enabling this
approach is the series of 4 shunt transformers. The yellow burst
waveform in the scope picture is the drive voltage activating each of
the 4 shunts. See Picture 16 for more discussion
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