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!