Laser Beam Transport and Integration. AWAKE Collaboration meeting. Mikhail Martyanov Christoph Hessler CERN, EN-STI-LP Valentin Fedosseev CERN

M.Martyanov, CERN2 AWAKE Experiment Laser room e-gun room p + beam e - beam laser beam Laser safety shutters Laser shutters Fast valves plasma e- spectrometer Laser dump p + / e - diagnostics CV SAS AWAKE gallery Control room 1km Laser / p + merging point

Overview Short intense laser pulse is needed for: – to create a 100% ionized plasma – moving ionization front is a source of perturbation for proton-laser instability (micro-bunching and wake-field with a stable phase) Plan for the Laser system: – First it is delivered to MPP Munich for plasma experiments - mid 2014 – Then it goes to CERN- Autumn M.Martyanov, CERN3

Overview Laser system comprises: - laser with 2 beams (for plasma and for the e-gun) - delay line is possible in either one of these beams - focusing telescope (lenses, in air), long 40m focusing - optical compressor (in vacuum) - small optical in-air compressor and 3 rd harmonics generator for e-gun Laser parameters for plasma: - max energy 450 mJ - pulse duration 120 fs after compression - max beam diameter 40 mm Only reflective optics on the way Rule of thumb (B<1): I[GW/cm 2 ]  L[cm]< M.Martyanov, CERN4

Laser System Base-line Laser, Telescope and Compressor are in the laser room Focusing down to 40 meters to the center of the plasma Back solution: Compressor and Telescope are next to merging point in the proton tunnel Focusing down to 25 meters to the center of the plasma Question is if this possible? Crucial points are: Focusability of the laser beam down to 40 meters, ionization dynamics, diffraction? No detailed information on the laser system yet (beam quality) The placement of the optical compressor and the focusing telescope has an impact on the position of the anew drilled connection tunnel Availability of vacuum components for the compressor and telescope is under study Torr “easily” achievable. Pellicle or differential pumping as an option to go better M.Martyanov, CERN5

M.Martyanov, CERN6 Scope of Laser Line WP Laser room preparation -Clean room, cooling and ventilation, facilities -Access control Laser transfer line to the plasma cell -HV vacuum line -Remote control of the mirrors -Laser beam position monitoring Laser transfer line to the photo-gun -Fore-vacuum line -Remote control of the mirrors -Laser beam position monitoring -In-air compressor and 3 rd harmonic generation <- Electron source WP Laser installation -Laser arrangement on the tables -Integration to the AWAKE environment

 1m compressor 2 x 1 m optical table SAS CV units 4m 3m 0.9m 2 x 1 m optical table 2.5 x 1 m optical table 2.5 x 1 m optical table Arrangement in the Laser Room Fore-vacuum laser transfer line for e-gun (on the ceiling) M.Martyanov, CERN7 PP+ power supply 600x600x(H)850 CCM rack 700x800x(H)1400 ~1m

Three optical tables: 2x1, 2.5x1, 2.5x1 m 1 – MENLO oscillator,500x500 2 – Stretcher,1000x500 3 – Regen / preamp,1000x800 4 – Green pump for (3) 5 – 600mJ amplifier,1500x800 6 – Green pump for (5),500x200 7 – Focusing telescope,1000x200 8 – Delay line for e-gun Laser Arrangement on the Tables M.Martyanov, CERN8

4.000 m 3 /h F 30 Pa15 Pa0 Pa Technical RoomLaser RoomSAS 4 m14 m2 m CV technical room already quite small. Other solutions? Access to CV technicians in the clean room for M&O. Very dry air from surface -> comfort and electronics? Laser room air-conditioning principal (by Michele Battistin) M.Martyanov, CERN9

Fresh air supply from surface Air supply duct to the clean room Air extraction to TCV4 CV first integration (by Michele Battistin) M.Martyanov, CERN10

M.Martyanov, CERN11 Laser Room – Integration 3D Model (by Frederic Galleazzi)

M.Martyanov, CERN12 Laser Room – Integration 3D Model (by Frederic Galleazzi)

TT41 – Laser Beam – Civil Engineering (by Frederic Galleazzi) M.Martyanov, CERN13 Safety laser shutter Vacuum pump Vacuum shutter Laser shutter

Mirror Chambers Preliminary Design (by Nicolas Chritin) M.Martyanov, CERN14

Laser beam is not centered on the mirror in horizontal plane, but centered in vertical. The gap between beams is =2mm The gap between proton beam and a mirror is 1mm  Footprint of the laser beam on the mirror 37=26  sqrt(2) Laser beam  26 Mirror  50, S=12 Fused silica Proton beam  12 Beams separation 21mm Towards the plasma p + from SPS M.Martyanov, CERN15 Laser and p + merging

M.Martyanov, CERN16 Laser Beam Size Downstream Merging (not to scale) Laser beam  merging Mirror  50, S=12 Fused silica Proton beam  12 Beams separation 21mm p + from SPS Plasma cell 20m10m 20m  26 Additional laser shutters Fast valves Laser dump Be-window for p+ Experimental area Laser Safety Shutter

SystemTo define / To do Laser room, SAS, CVAir 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, position has been defined Access to laser room and p- tunnel AWAKE access concept including Laser Access Modes to p-tunnel and e- gun room, safety shutters Ti:Sa laserLaser arrangement on three tables to be defined by AMPLITUDE. Arrangement of chillers and electronics – to be defined Controls and diagnostics are provided by AMPLITUDE Detailed specification is required Vacuum pulse compressor and focusing telescope. Who supply compressor chamber ? Vacuum agreed to be 1e-06mbar in the compressor Transfer line to p-tunnel Merging point chamber To be designed, work has been started Transfer line to e-gun Separate small compressor 3 rd harmonic generation In fore-vacuum, to be designed Laser installation in laser room M.Martyanov, CERN17

SystemIssues Laser beam in the p-tunnelSteady 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 timing measurements On demand or maintenance diagnostics: Auto-correlator, angular spectrometer, phase-front detector, etc. Laser beam in the e-gun room (small compressor and 3 rd harmonic generation are next to the gun) Steady diagnostics: Virtual cathode CCD, UV energy meter, some IR signal coupled to a fiber for rough timing measurement On 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 installation in p-tunnel and in e-gun room M.Martyanov, CERN18

Thank you! M.Martyanov, CERN19

M.Martyanov, CERN20

4.000 m 3 /h F 30 Pa15 Pa0 Pa Technical RoomLaser RoomSAS 2 m ! 15 m 3 m CV technical room already quite small. Other solutions? – Make it even smaller ! Access to CV technicians in the clean room for M&O – Assume it is a rare event ! Very dry air from surface -> comfort and electronics? – Poor comfort (manageable), for electronics – to be considered Laser room air-conditioning principal (our proposal) M.Martyanov, CERN21

Attenuated energy option Max 280 mJ Full energy focusing option Max 450 mJ Plasma here Last turning mirror Very smooth focusing Max 100 mJ Focusing geometry, 40 meters Simple propagation of a super-Gaussian beam, no plasma

Focusing geometry, 40 meters Attenuated energy option, Super-Gaussian beam ionizing plasma, 100mJ pulse Ionization ratio in plasma dE = -30mJ