Automating 805 Testing - MICE

fanaticalpumaMechanics

Nov 5, 2013 (3 years and 8 months ago)

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Automation of the 805MHz
cavity conditioning
procedure

Ajit Kurup




MuCool Test Area RF Workshop,
Fermilab


22
nd


August 2007

Page

2

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

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.

Page

3

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

DAQ Hardware

Signal

Generator

Analogue

Oscilloscope

Terminal

Control

Electronics

Digital

Oscilloscope

Log book

10Hz clock

Page

4

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

DAQ Hardware (2)

Signal

Generator

Analogue

Oscilloscope

Power Amplifier

Klystron

Modulator

Waveguide

Directional Coupler

Cavity

forward power

reflected power

Fast ~
-
30dBm

attenuator

(threshold between
reflected power
peaks)

10Hz clock

Fast Switch

(vacc > 6X10^
-
8 torr ||

2 consecutive breakdowns)

ACNET

Control

Electronics

vacuum probe

voltage probe

Page

5

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

Automation of the Conditioning Procedure

Signal

Generator

Analogue

Oscilloscope

Power

Amplifier

Klystron

Modulator

Waveguide

Directional Coupler

Cavity

forward power

reflected power

10Hz clock

ACNET

Control

Electronics

vacuum probe

voltage probe

Digital

Oscilloscope

rf enable

Fast ~
-
30dBm

attenuator

(threshold between
reflected power
peaks)

Fast Switch

(vacc > 6X10^
-
8 torr ||

2 consecutive breakdowns)

Page

6

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

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.


Page

7

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

Front Panel
-

Initialisation

Page

8

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

Front Panel
-

Monitor Loop

Page

9

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

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 20

s @ 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).

Page

10

Automation of the 805MHz cavity conditioning procedure


MuCool Test Area RF Meeting, Fermilab


22
nd

August 2007

Ajit Kurup

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!