Turning Gun RF ‘ON’

Preparation

  1. Ensure gun cavity tuners are in force mode
  2. Set force to approximately 500 N

Run Initialization sequencer

  1. The following steps are all accomplished by using the RF Init button
  • 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” (approximately 400 kHz from nominal)
  • Turn RF ‘ON’

Turn RF 'On' in open loop

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

Gun SSA Balancing

  1. Balance SSAs if reflected power is too high
    • For the gun system reflected power should be less than 20 W per channel

Go to nominal amplitude - iterate steps 1 - 4 according to 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)

~ 2000

.07

~10000

.35

~18000

0.77

Increase the duty cycle

  1. Increase duty cycle in 5% 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.

Activate the gun cavity tuners

  1. Drive the gun cavity toward nominal frequency by adjusting tuners in force mode
  2. Adjust in 50 N steps with 15 – 20 seconds per adjustment
  3. Stop when cavity RF frequency is within 180 Hz of nominal
  4. Expect the final force to be 3000-5000 N


Stop tracking cavity frequency

  1. Transition to a fixed RF frequency is accomplished with a single button sequence: “Keep at Nominal”
  • Turn follow cavity frequency ‘OFF’
  • Turn tuner frequency mode ‘ON’

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 Lin (PRL)

  1. 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 (this step might be omitted, but needs testing first)
  • 99.9%
  • 99.95%
  • 99.99%
  1. 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 0.5% lower than the current setpoint

The CW Power Ratio should be set to 0.005 for this transition





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