Accelerator Handbook

Put the Faraday cups in.

Switch OVERVOLTAGE PROTECTION to DISABLE.

Switch the control mode to GVM.

Slowly turn the CONTROL GAIN to zero while watching the grid voltage. If the grid voltage rises above -5 volts, reduce the CHARGING VOLTAGE to keep the grid voltage less than -5 volts, then continue reducing the CONTROL GAIN to zero.

To go to a higher energy move the CORONA PROBE POSITION “OUT” while raising the CHARGING VOLTAGE. NEVER allow the GRID VOLTAGE to go more negative than -5 VDC during this operation.

To go to a lower energy move the CORONA PROBE POSITION “IN” while lowering the CHARGING VOLTAGE. NEVER allow the GRID VOLTAGE to go more negative than -5 VDC during this operation.

Set the TERMINAL VOLTAGE Dial to the desired value. The dial is 2 turns per MV (set the dial to twice the GVM you want). You may have to add some upcharge after setting the dial.

Raise the CONTROL GAIN to 2-3 for low current beams, around 5 for high current beams. The system is now controlling in GVM mode.

Make fine adjustments to the TERMINAL VOLTAGE Dial to reach exactly the desired GVM value.

Switch OVERVOLTAGE PROTECTION to ENABLE.