Preparation

  1. Ensure buncher chiller is “ON”
  2. Set the temperature to 40 deg C

Both these steps are a part of the Buncher RF on sequencer, but it still helps to do this separately for the initial turn on to be sure the chiller is on and ready

Initialize the Buncher RF

  1. The following steps are all accomplished by using the RF Init button
  • Clear Interlocks
  • Turn buncher chiller feedback loop ‘OFF’
  • Turn buncher cavity chiller ‘ON’ and set to 40 deg C
  • Turn follow PRL ‘OFF’
  • Set phase rotation to 0
  • Set Duty Cycle to 5%
  • Set PW to 20 ms
  • Set Frequency tracking ‘ON’
  • Set Gain Phase tracking to ‘ON’
  • Turn A&P Feedback Close Loop ‘OFF’
  • Set cavity frequency to “cold”
  • Turn RF ‘ON’

Turn Buncher RF output 'ON'

  1. Open ‘Control Loop’ screen
  2. Set Clip DAC at: 2500
  3. Set DAC to 2000

Balance SSAs

  1. Balance SSAs if reflected power is too high using the balancing script

For the buncher system reflected power should be less than 5 W per channel


Adjust amplitude up to 0.135 MV in steps according to the table

  1. Close the Amp/Phase feedback loop
  2. Adjust the clip DAC setting
  3. Increase the amplitude in volts
  4. Adjust the clip DAC setting as needed

Clip DAC (counts)

Amplitude setpoint (MV)

~2500

0.02

~6500

0.05

~10500

0.08

~17500

0.135

Increase the duty cycle up to 99.85%

  1. Increase duty cycle in 10% increments (approximately every 30 seconds)
  2. Stop at 99.85%

Increments to duty cycle will quickly warm the RF cavity causing it to tune. 

Monitor the I vs. Q and assist the gain phase tracking loop if necessary.

Actuate the buncher cavity tuner

  1. Wait for buncher chiller temperature readback to equal temperature stability (thermal equilibrium)
  2. Adjust buncher chiller setpoint to drive cavity to nominal frequency (2 kHz per 0.1 deg C)
  3. Stop when cavity is within 2 kHz of nominal and stability is reasonable
  4. Turn Temp Tuning “Feedback On”
  5. Turn off frequency tracking with “Keep at Nominal”
  6. If the landing frequency from the process above is not 0 Hz from the desired nominal frequency, then adjusted the drive to nominal in 180 Hz steps

Lock RF to the Phase Reference Line (PRL)

Transition to following PRL is accomplished with a single sequenced button: “Follow PRL”

  • Open A&P feedback loop
  • Initiate following the PRL
  • Close A&P feedback loop

Transition to CW RF

1.Ramp to 99.99% duty cycle

  • 99.9%
  • 99.95%
  • 99.99%

2.When at 99.99% duty cycle, transition to CW is accomplished with a single sequenced button: “To CW”

  • Set duty cycle to 100%
  • Set amplitude to 0.8% lower than the current setpoint

The CW Power Ratio should be set to 0.008 for this transition




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