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Automation of the 805MHz cavity conditioning
procedure
Ajit Kurup
MuCool Test Area RF Workshop, Fermilab
22nd August 2007
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 2
Automation of the 805MHz cavity conditioning procedure
Introduction• Currently, the 805 MHz cavity button tests
conditioning is “done by hand”.
• Automating this procedure should speed up time to condition the cavity and will perform the conditioning in a systematic way.
• Existing hardware has been used and a Labview program written to automate the conditioning procedure.
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 3
Automation of the 805MHz cavity conditioning procedure
DAQ Hardware
Signal Generator
Analogue Oscilloscope
Terminal
ControlElectronics
Digital Oscilloscope
Log book
10Hz clock
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 4
Automation of the 805MHz cavity conditioning procedure
DAQ Hardware (2)
Signal Generator
Analogue Oscilloscope
Power Amplifier Klystron
Modulator
Waveg
uid
eD
irection
al Co
up
ler
Cavity
forward power
reflected power
Fast ~-30dBmattenuator(threshold between reflected power peaks)
10Hz clock
Fast Switch(vacc > 6X10^-8 torr ||2 consecutive breakdowns)
ACNET
ControlElectronics
vacuum probe
voltage probe
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 5
Automation of the 805MHz cavity conditioning procedure
Automation of the Conditioning Procedure
Signal Generator
Analogue Oscilloscope
Power Amplifier Klystron
Modulator
Waveg
uid
eD
irection
al Co
up
ler
Cavity
forward power
reflected power
10Hz clock
ACNET
ControlElectronics
vacuum probe
voltage probe
Digital Oscilloscope
rf enable
Fast ~-30dBmattenuator(threshold between reflected power peaks)
Fast Switch(vacc > 6X10^-8 torr ||2 consecutive breakdowns)
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 6
Automation of the 805MHz cavity conditioning procedure
Logic of the Algorithm• A breakdown is identified by looking at the time between the two peaks of
the reflected power signal. If this is less than the width of the rf enable pulse (within a certain error) then a breakdown is assumed to have occurred.
• The program calculates the breakdown fraction over a short period and a longer period. If the breakdown rate is higher than the specified limits then the amplitude is reduced otherwise it is increased. This continues until the target amplitude is reached.
• The program also checks for consecutive breakdowns and if this is higher than the specified limit then the amplitude is decreased.
• Once the target amplitude is achieved then the program will either keep monitoring for breakdowns indefinitely or will terminate.
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 7
Automation of the 805MHz cavity conditioning procedure
Front Panel - Initialisation
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 8
Automation of the 805MHz cavity conditioning procedure
Front Panel - Monitor Loop
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 9
Automation of the 805MHz cavity conditioning procedure
Testing the Conditioning Program
• No rf available during shutdown period– Had to test the program by simulating the reflected power signal
using a signal generator (Thanks to Al Moretti)
• Generate 2 pulses separated by 20s @ 10Hz repetition rate.
• Can simulate a breakdown by reducing the time between the 2 pulses.
• Stability check– Left the program running over the weekend (i.e. from 3:30pm
Friday to 11:30am Monday) and the program was still working as normal (i.e. no latency problems or memory leaks).
MuCool Test Area RF Meeting, Fermilab 22nd August 2007Ajit Kurup Page 10
Automation of the 805MHz cavity conditioning procedure
Summary and Plans• Conditioning program has been written and some basic tests have been
done.
• Need to test the program which finds the resonant frequency of the cavity and include it in the main program.
– Al is setting up a “dummy” cavity. Should be ready for testing tomorrow.
• Look to see if it’s possible to speed up time to adjust the amplitude.
• Need to include vacuum signals.– Need a daq card (should be purchased soon).
• May need to make increments and decrements non-linear
• Include logging routines.
• Test with the real cavity and rf!