Spark Gap

In order to trigger the high voltage between the plates with the coincidence pulse, we need to input it to the high voltage supply, the spark gap. But the coincidence pulse cannot be used directly as a trigger, we need another device between these two. Th is device is the Spark Gap Driver Amplifier. Using a positive high voltage to amplify the signal, it uses the coincidence pulse and modify it to get a signal similar to the one shown in figure below as the trigger input. The discharge of a capacitor creat es a spark between two electrodes, like for the spark gap high voltage supply, and the pulse is sent to its trigger input.

Circuit of the Spark Gap high voltage supply

The Spark Gap high voltage supply is the source of the high voltage between the plates. As it can be seen in the figure above, it is an RC circuit with a capacitor that discharges whenever the trigger is on.

1. When there is no voltage at the HV input, no current is flowing, nothing is happening.
2. When we apply a voltage at the HV input, the 6800 pF capacitor charges until the current stop flowing.
3. When the voltage at the trigger input is up, the two 10pF capacitors charge.
4. When the voltage at the trigger input is suddenly down, i.e. when a coincidence happens, the two 10 pF capacitors discharge and a spark is produced at the trigger electrode. This spark induces sparks at the other electrodes.
5. When these sparks occur, the node before the 6800 pF capacitor is at ground, then the capacitor discharges very rapidly in the chamber.

A clearing field of 100 V is also applied to the circuit.