Laser news

AWAKE performance meeting25.11.2013

Overview• There was a meeting on 05.11.2013 with the supplier

of the laser system (AMPLITUDE)• No new information on the laser system yet• The placement of the optical compressor and the

focusing telescope has to be defined before drilling the connection tunnel

• Availability of vacuum components for the compressor and telescope is under study.

• 10-6 Torr “easily” achievable. Pellicle or differential pumping as an option to go better

• Provocative: is 10-8 Torr overestimated?

Some measurements of laser room with respect to merging point

System To define / To doLaser room, equipped with a big SAS

Air circulation, conditioning, humidity, filters, circuits (electrical, demineralized water, tap water, compressed air, control cables), safety (fire/smoke alarm), shutters, access etc.

Connection tunnel 40cm Drilling, coordinates of laser beam to be definedAccess to laser room and tunnel AWAKE access concept including Laser Access Modes to p-tunnel and e-

gun room, safety shuttersTi:Sa laser Arrangement in a squeezed room, max laser table width is 1m

Chillers and electronics are below the tables or in the separate ventilated rack/cabinet or in the big SAS

Vacuum pulse compressor and focusing telescope.

HV (10-6 Torr) or UHV (10-8 Torr): pellicle or differential pumping

Placement is not defined yet (->AMPLITUDE)!Placement in the laser room is a base-lineIn case of p-tunnel everything must fit between p-beam and wall,“dirty” environment in p-tunnel is not good for compressor/telescope installation and maintenance

Transfer line to p-tunnelMerging point chamber

HVUHV (only 2 mirrors, possibly without in-vacuum motors)

Transfer line to e-gunSeparate small compressor3rd harmonic generation

In fore-vacuumNext to the gun

Laser dedicated list of “Things to Do”:Laser Installation

Preliminary

AWAKE access will be discussed preliminary on the dedicated meeting

Courtesy of C.Hessler

System IssuesTi:Sa laser Controls and diagnostics are provided by the supplier of the laser

system (AMPLITUDE)Vacuum pulse compressor and focusing telescope

Diagnostics are provided by the supplier

Laser beam in the p-tunnel Steady diagnostics:Focused beam spot monitor (virtual plasma, the same long distance run); near field before merging mirror; screens before and after plasma tube sensitive to “both” beams (laser, electrons, protons) also equipped with fiber-coupling for rough timimg measurementsOn demand or maintenance diagnostics:Auto-correlator, angular spectrometer, phase-front detector, …

Laser beam in the e-gun room(small compressor and 3rd harmonic generation are next to the gun)

Steady diagnostics:Virtual cathode CCD, UV energy meter, some IR signal coupled to a fiber for rough timimg measurementOn demand or maintenance diagnostics:Auto-correlator, angular spectrometer, …

Delay control between pulses: ionization and e-gun

Delay line either on one of 2 beams, proper delay simulation required.Split after RegAmp was proposed by AMPLITUDE with 2.5mJ IR output for e-gun

Laser dedicated list of “Things to Do”:Laser Operation

OTR or laser light- Imaging (lens system and CCD)- Capture and measure with PhD or

streak-camera (coupling to a fiber or lens system)

- Other techniques

Alignment of 3 beams

plasma

p-beamlaser-beam

e-beam

BPM

BPM

Alignment of 3 beams• 3 beams (protons, electrons and laser) have to be align in space and

time• Transverse accuracy ~ 0.2mm• Angular accuracy ~ 0.2mm / 10 m = 20rad• Timing electrons-laser ~ 100fs – alignment by response? Rough

alignment is needed anyway• Timing protons-laser ~ 10ps – alignment with fast PhD and scope

possible, 1pJ of light is required. Streak-camera.

For robust alignment of 3 beams we need an optical signal which comes from the same screen sensitive to 3 beams (the power of laser beam can be reduced for the measurements not to damage the screen)

Thank you