CIS OnCall and Troubleshooting

250V FSD Comparator Faults

Use comparator circuit in ISB monitoring HVPS output to determine gun voltage is within a window

1. Faults can be real (gun HV is out of range) or false (comparator is drifting)

Gun HV bad - are the following drifting ...
Check archived precision read back of Ross probe
Check archived HVPS lock set point
Check archived BPM orbit at IPM1I02

Comparator bad - provided gun HV stable ...
Window drift during SAD can be found at startup
Window drift sensitive to temperature variation e.g. seasonal temperature swing
Window set too tightly by Ops
To set window
# While clicking FSD clear button vary POT until resets to find a good region
# High Limit : Increase POT while clicking until fault occurs, then decrease until fault clears and record new high value
# Low Limit : Decrease POT while clicking until fault occurs, then increase until fault clears and record new low value
# Set POT at center of new low and high values; maybe repeat to get consistent values

Beam Noise

Use FastSEE BPM Mode to diagnose intensity and position from injector BPM's with 4 microsecond sampling

1. To start : Accel Menubar => EDM => BPM => New FastSEE Control
2. MAC or Channel Access is required
3. Choose a BPM mode and BPM by selecting corresponding ioc e.g. iocse11

BPMSEE mode
Non-invasive
BPM spikes update correctly
Less samples limit to lower frequency
Make sure FastSee Light is ON

FastSEE mode
Invasive
BPM spikes update erratically
More samples for higher frequency ~60kHz