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Turning Gun RF ‘ON’
Preparation
- Ensure gun cavity tuners are in force mode
- Set force to approximately 500 N
Run Initialization sequencer
- 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
- Open ‘Control Loop’ screen
- Set Clip DAC at: 2500
- Set DAC to 2000
Gun SSA Balancing
- 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
- Close the Amp/Phase feedback loop
- Adjust the clip DAC setting
- Increase the amplitude in volts
- Adjust the clip DAC setting as needed
Clip DAC (counts) | Amplitude setpoint (MV) |
~ 2000 | .07 |
~10000 | .35 |
~18000 | 0.77 |
Increase the duty cycle
- Increase duty cycle in 5% increments (approximately every 30 seconds)
- 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
- Drive the gun cavity toward nominal frequency by adjusting tuners in force mode
- Adjust in 50 N steps with 15 – 20 seconds per adjustment
- Stop when cavity RF frequency is within 180 Hz of nominal
- Expect the final force to be 3000-5000 N
Stop tracking cavity frequency
- 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)
- 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
- Ramp to 99.99% duty cycle (this step might be omitted, but needs testing first)
- 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