Accelerator Handbook

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==== Changing Terminal Energy ====

  - 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.

Accelerator Handbook

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