The Flash Beam Loss Monitor System · [1] A.Ignatenko, Desy-Thesis-2015-016 • Kind of BLM,...

Thomas Wamsat | Flash Operator Training | 3. Nov. 2017 | Seite 1

MDIDiagnose und Instrumentierung

The Flash Beam Loss Monitor System

Thomas Wamsat, MDI

for the diagnostics team

FLASH Operator Training

3.11.2017

FLASH.Free-Electron Laser

in Hamburg


Content

> Introduction

> Structure and functionality

> Alarms, thresholds etc.

> Beam Halo Monitor

> Ionisation Chamber

> Troubleshooting


in Hamburg


Introduction

• 85 BLMs installed in Flash1• 55 BLMs installed in Flash2• 6 BLMs will be installed in FlashForward

• Protecting accelerator components fromdamage and excessive activation (as part ofthe machine protection system)

• In particular protecting the undulators, takeseriously care about losses in undulator area!


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Structure and functionality

• uTCA based electronics, distributed along the machine in severalCrates (3 @ Flash1, 4 @ Flash2, 2 @ FlashForward)

• 8 channel RTM with analog signal processing and 45 MHz 14bit ADC• DAMC2 FPGA board for digital signal processing• HV generation within the BLM, no HV cables needed• Test LED to get alive feedback

• How it works in short words: Charged particles (beam losses) hit the scintillator whichconverts them into light. The photomultiplier tube (PMT) transforms the light into an electric signal


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Alarms, thresholds etc.

Single pulse alarmTriggers, as soon as the set limit is exceededMulti pulse alarmNeeds two terms to trigger: 1. signal exceeds threshold

2. number of allowed pulses overshootIntegral alarmTriggers if the number of integrated samples exceeds thresholdComparator alarmAnalog backup, threshold is chosen thus it triggers a little bitabove single thresholdHV tracing alarmWhen the high voltage gets too low so the PMT cannot work properly itcauses a permanent alarmSlow protection alarm (not enabled at Flash)Counts recurrent alarms from macropulse to macropulse, if alarm is gonethe counter decreases. When number of recurrent alarms is exceeded itcauses a permanent alarm � no beam possibleReset by operator is needed


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Alarms, threshlods etc.

• Scaling the y-axis to single alarm threshold

Same loss, differentsingle pulse threshold

• Resolution of panels not high enough to show discrete bunches


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Alarms, threshlods etc. FLASH.Free-Electron Laser

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BLM Slow Protection

• Stops beam as in panels explained conditions• Can be disabled by operators for max. 30min (causes an logbook entry)• Responsible for this system: Christian Grün


Beam Halo Monitor (BHM)

[1] A.Ignatenko, Desy-Thesis-2015-016

• Kind of BLM, crystals instead of scintillators• Direct in front of the dump within the concrete block• Uses same electronics and panels


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Ionisation Chambers FLASH.Free-Electron Laser

in Hamburg

• Dump fibers and ionisation chambers inparallel along the last two meters beforethe dump window

• Ionisation chambers are not connected to anythresholds or MPS, just observable

• Dump fiber behave like normal BLMs


Troubleshooting

If the BLM signal looks like this:

-> Probably the ADC lost its config• Open the Controls window in the Main Taskbar and click on

MicroTCA Systems• Use the Flash1 DIAG or Flash2 DIAG slide respectively• Search for the panel, which includes the faulty BLM• Click on FADC config, if this does not help, call an expert


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Thank you for your attention


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The Flash Beam Loss Monitor System · [1] A.Ignatenko, Desy-Thesis-2015-016 • Kind of BLM,...

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Transcript of The Flash Beam Loss Monitor System · [1] A.Ignatenko, Desy-Thesis-2015-016 • Kind of BLM,...