Laser Arm for Photo-injector Mikhail Martyanov, Valentin Fedosseev, Christoph Hessler AWAKE PEB meeting , CERN

“2.5 mJ” “25 mJ” splitter mechanical pulse selector 25 mJ 650 mJ Amplifier atten Vacuum compressor Compressor THG atten UV to e-gun to plasma splitter mechanical pulse selector 2.5 mJ 650 mJ Amplifier atten Vacuum compressor Compressor THG atten UV to e-gun to plasma Budgetary options for e-gun arm

650 mJ Amplifier atten Vacuum compressor Compressor THG splitter mechanical pulse selector 2.5 mJ 25 mJ Amplifier atten Option “Independency” for e-gun arm “+25 mJ” OptionWhat to buy “2.5 mJ”mechanical pulse selector, attenuator “25 mJ”mechanical pulse selector, attenuator, splitter “+25 mJ”mechanical pulse selector, attenuator, 25mJ amplifier

“300 fs” SHG BBO 0.6 mm 780(o)+780(o)=390(e) Zero-order dual 780nm horizontal 390nm vertical SHG BBO 0.4 mm 780(o)+390(o)=260(e) 260nm vertical 780nm horizontal 390nm vertical Harmonic separator 780nm horizontal 390nm horizontal “10 ps chirped” SHG BBO 0.2 mm 780(o)+780(o)=390(e) GVM compensator ~1mm Silica / Calcite Zero-order dual 780nm horizontal 390nm vertical 780nm horizontal 390nm vertical SHG BBO 0.1 mm 780(o)+390(o)=260(e) 260nm vertical 780nm horizontal 390nm vertical Harmonic separator 780nm horizontal 390nm horizontal 60  80 fs delay 780 w.r.t 390 Third Harmonic Generation (THG) Options EKSMA Optics AMPLITUDE Technologies

EKSMA OpticsEUR /2 zero-order WP, 780 nm 310 SHG BBO 20 x 20 x 0.2 mm (o)+780(o)=390(e) SHG BBO 10 x 10 x 0.6 mm660For “10ps chirped” GVM compensator (Silica / Calcite / BBO …)~500 Zero-order dual WP,  17mm 410 THG BBO 20 x 20 x 0.1 mm (o)+390(o)=260(e) THG BBO 10 x 10 x 0.4 mm660For “10ps chirped” Harmonic separation mirror, HR 260nm, HT nm,  25 x 3 mm 175 Mounts~1000 /2 zero-order WP, 260 nm 345 Total9860 Spare optics8685 Third Harmonic Generation (THG) Options

“300 fs” Chirped THG scheme 3D-simulation Output, I k (x, y=0, t) 780 nm390 nm260 nm

“10 ps” Chirped THG scheme 3D-simulation Output, I k (x, y=0, t) 780 nm390 nm260 nm

UV Stretcher (if needed) Transmission UV diffraction gratings 50 x 50 mm 1200 grooves / mm, 26.7  blaze angle 100 fs -> 10 ps L = 350 cm !!! 7+ meters delay L, gratings base UV stretcher layout Gratings available from EDMUND / OPTOMETRICS / SHIMADZU … Estimated stretcher price ~ 5000 EUR

Summary For a short bunch operation (“0.3 ps” option) -THG easy and straight-forward -Any bunch charge can be produced -No need for a “25 mJ Amplifier”, 2.5 mJ available now is enough For a long bunch operation (“10 ps” option) -For the ultimate 1nC case with Cu-cathode a good THG efficiency is required -Robust THG scheme simulation shows promising results: 2.2mJ UV from 25 mJ IR -“25 mJ Amplifer” is needed -For lower charges (or with Cs 2 Te cathode) existing 2.5 mJ output might be enough -UV stretcher is technically feasible and relatively cheap -No need for UV stretcher if chirped THG works well (can be easily tested at MPI)

Laser Requirements Table OptionCu-cathodeCs2Te-cathode 0.3 ps, 0.1 nC2.5 mJX 10 ps, 0.2 nC25 mJ Amplifier or 2.5 mJ 2.5 mJ 10 ps, 1nC25 mJ Amplifier2.5 mJ -Robust THG scheme proposed, to be tested for chirped 10ps -UV stretcher probably is not needed