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output to
accelerator area
drive laser:81.25 MHz, sync’d to master RF
= 1064 nm~7 ps pulses
~10 watts average (~120 nJ/pulse)
chopper wheel:~100Hz, ~120s opening
solenoid shutter:1, 2, 5, 10, 20 Hz
Pockels cell:5ns – 120s opening
frequency doubler:output = 532 nm
~ 40 nJ/pulse
pulse train monitor
photodiode
variable attenuator
pulse stacker:output ~28 ps pulses
variable beam size optics
shutter for release
to accelerator
Photo-injector laser: functional overview
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Photo-injector laser: functional overview
drive laser:81.25 MHz, sync’d to master RF
= 1064 nm~7 ps pulses
~10 watts average (~120 nJ/pulse)
chopper wheel:~100Hz, ~120s opening
solenoid shutter:1, 2, 5, 10, 20 Hz
Pockels cell:5ns – 120s opening
frequency doubler:output = 532 nm
~ 40 nJ/pulse
pulse stacker:output ~28 ps pulses
variable beam size optics
output to
accelerator area
pulse train monitor
photodiode
variable attenuator
shutter for release
to accelerator
monitored/changedin normal operation
changed occasionally
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Laser room
light box
virtual cathode
lasersource exit from
laser room
cathode
[mm][m
m]
beam on virtual cathode
photo-injector lasers transport
mirrors on translation stagescathode
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photo-injector lasers transportMovable mirrors for changing beam position on cathode
“VTM”vertical
“HTM”horizontal
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CW “unchopped”pulse train
chopped, 532nm, train(macrobunch, before attentuator)
master 81.25MHz delivered to laser room
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Laser timing signals
signal used for RF triggering(also with ~23 ms advance)
general trigger signal(for BPM’s, cameras, etc)max pretrigger ~270s
Chopper detect
chopper open
shutter open
pockels cellopen/close
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drive laser shutter open/closed (laser operators key required)
shutter to accelerator open/closed(general control panel operation)
laser macro-bunch length & external
trigger signals
Laser system controls...
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Chan A:Pockels cell open (~270s)
Chan B:macro-pulse width(~5ns- 100s)
Chans C, Dused by BPMs
control can be released for
manual “local” operation in laser room
“internal” triggeringused for equip testing
when laser not operational
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opens laser position control..
left-right defined fromelectron frame
NOT looking back at cathode
KNOWN “bug”: if power lost to motor control, the control-system zero position will change.
(restarts at zero on control system, but motors actually at position as before power cycle)
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ERLPcon2 desktop
“Pylon viewer”
Viewing the (real) cathode
New (more reliable) camera, BUT, not yet tested with laser beam on cathode....Sensitivity to be determined on startup
camera synchronised to laser macro bunch train
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Viewing the (real) cathode...
as viewed with old camera....new colour camera to be used this commissioning period
Looking at scattered light from cathode, though side port on light-box
• not enough light with short macro bunch trains• observed profile dependent on scattering flatness of cathode• position is reliable (not dependent on survey, etc)
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Viewing the virtual cathode
“virtual cathode” icon on ERLPcon1 desktop
no camera control screen shots for now....(will add later)
from underneath light-box
cross-hair for alignment reference
variable attenuator (for camera sensitivity/protection)
• sensitive enough for monitoring laser with “few-bunch” train lengths• beam position accuracy depenent on survey
(can cross-check with real cathode at long bunch trains)
camera synchronised to laser macro bunch train
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Laser-RF synchronisation
spacing set by round trip
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