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

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

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

photo-injector lasers transportMovable mirrors for changing beam position on cathode

“VTM”vertical

“HTM”horizontal

CW “unchopped”pulse train

chopped, 532nm, train(macrobunch, before attentuator)

master 81.25MHz delivered to laser room

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

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...

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

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)

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

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)

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

Laser-RF synchronisation

spacing set by round trip