Mid-IR lasers for energy frontier plasma accelerators Igor Pogorelsky Mikhail Polyanskiy (BNL ATF) Marcus Babzien (BNL ATF) Wei Lu (Tsinghua Univ.) Wayne Kimura (STI Optronics) AAC2016 WG1

3 2 Roadmap to plasma colliders LBNL Workshop 2016 Design 2025 Build 2035

3 3 Slab lasers Disk lasers Fiber lasers Main contenders

UCLA Neptune Lab.ATF CA NY MARS PITER CO 2 Laser Facilities for Strong-Field Physics CO 2 Laser Facilities for Strong-Field Physics 3

5 Simulations by Wei Lu Propagation in a matched channel 3D PIC simulations performed for a 400 fs 60 TW CO 2 laser focused to w 0 =262.5  m at the entrance to a 3.2x10 15 cm -3, matched, parabolic plasma channel. Need femtosecond multi-TW CO 2 laser !

3 6 Parameter 1-PW YAG100-TW CO 2 Laser wavelength (  m) 110 Laser pulse duration (fs) Laser peak power (TW) Laser energy (J) Normalized laser field 88 Plasma density (×10 16 cm -3 ) Bubble threshold (TW) Critical laser power (TW) 43 Max acceleration length (cm) 1030 Accelerating field (GeV/cm) 20.2 Number per bunch (×10 10 ) 310 Bubble volume (mm 3 ) Parameters for bubble accelerator driven with 1-  m and 10-  m lasers. Bubble regime Conclusions: CO 2 needs lower n e ~n crCO 2 needs lower n e ~n cr E will be smaller E will be smaller but N e - higherbut N e - higher

7 Plasma collider options in quasi-linear regime From “Design considerations for a laser- plasma linear collider” C. B. Schroeder, 2008 Quasi-linear Bubble Quasi-linear regime provides better control over accelerating and focusing fields suitable to inject and accelerate both electrons and positrons

3 8 Parameter#1#2#3#4#5PIC*#6 Laser wavelength (  m) Plasma density (×10 16 cm -3 ) Plasma wavelength (  m) Laser pulse duration (fs) Laser radius (  m) Laser peak power (TW) Laser energy per stage (J) Number per bunch (×10 9 ) Single stage interaction length (m) Accelerating field (GeV/m) Energy gain per stage (GeV) Number of stages Collision rate (kHz) Average laser power per stage (kW) Linac length (stages 0.5 m apart) (m) Total laser power (MW) Representative sets of laser and plasma parameters for LWFA 1-TeV c.m. e − e + collider Adding CO 2 laser into equation

3 9 Parameter Ti:S CO 2 Laser wavelength (  m) Plasma density (×10 16 cm -3 ) Plasma wavelength (  m) Laser pulse duration (fs) Laser radius (  m) Laser peak power (TW)30075 Laser energy per stage (J)4052 Number per bunch (×10 9 )423 Single stage interaction length (m) Accelerating field (GeV/m) Energy gain per stage (GeV)102.4 Number of stages50208 Collision rate (kHz)100.3 Average laser power per stage (kW)40016 Linac length (stages 0.5 m apart) (m)65448 Total laser power (MW)202.6 Two optimum examples limited by beamstrahlung e - + e +  Beamstrahlung is irrelevant for gamma colliders From “Design considerations for a laser- plasma linear collider” C. B. Schroeder, 2008

Gamma collider Lepton linear collider can be converted to photon collider by ICS. This offers a possibility to study lepton-  and  interactions in addition to e − e + collisions. Although a  collider is presently not among the prime options for the next frontier accelerator, it is is considered as a valuable extension to a lepton collider.

3 11 Parameter  LWFA  -IP e + source Laser pulse duration (ps) Laser peak power (TW) Laser energy per stage (J) Laser focus radius (  m) Other Input ConditionsPlasma 3.5x10 15 cm TeV e-beam4 GeV e-beam Particle energy 2.4 GeV/stage 1.8 TeV -  40 MeV -  Number per bunch 2.3x10 10 N  /N e =1N g /N e =1 Single stage length 1.1 mRayleigh Application example  collider  collider e − e + collider Number of lasers Laser repetition rate (Hz) (30)150 Pulses in a train (optional) 1(10)100 Average laser power (kW) Wall plug power (MW) 2.63 (0.3)0.05 Cumulative table for CO 2 laser requirements

ε n =50 nm 10 μm a o = μm a o =

13 LWFA – ponderomotive action by a laser pulse results in electron heating to several MeV. PWFA – electrons are expelled by the Coulomb force of the driver-bunch with negligible heating. Ti:sapph “Trojan Horse” – concept of brightness transformer predicts  n =30 nm PRL 108, (2012) All-optical “Trojan Horse” PWFA CO 2 Ti:S

14 LWFA PWFA (low  ) ComptonFEL Concept of all-optical FEL

15 OPA: fs seed Stretcher + compressor = Chirped pulse amplification High-pressure, isotopic amplifiers Nonlinear compressor Compressor Non-linear compressor 70 J 50 J 2 ps 25 TW OPA Ti:Al2O3 Amplifier 1 Stretcher 35 µJ 350 fs 10 µJ 100 ps 100 mJ Amplifier 2aAmplifier 2bAmplifier 2c 10 J 100 fs 100 TW Collection of innovations: 100TW CO 2 concept laser

6-meter long CO 2 laser final amplifier Final amplifier CPA compressor Regen. Pre- amplifier

17 100TW CO 2 laser BESTIA 6-meter long final amplifier OPA Regen CPA Compr. Femto-sec Compressor CPA Stretch. Laser / e-beam interaction Ion acceleration 9-11  m 100 TW 100 fs a 0 = Hz Design Parameters:

18 Pressure10 atm Beam Size13 x 13 mm 2 Repetition Rate up to 500 Hz Pulse Energy1.5 J Average Power 750 W IonizationUV SOPRA (France) SDI (South Africa) Pressure5 atm Beam Size50 x 50 mm 2 Repetition Rate 100 Hz Pulse Energy10 J Average Power 1 kW Ionizationx-ray Commercially available high-repetition lasers 3

19 THYRISTOR APPEARS TO BE BEST CANDIDATE TO DRIVE LASER DISCHARGE  Solid-state switch with high-rep-rate capability (350 Hz) and long lifetime -Has been demonstrated in Marx banks -Maximum high voltage is acceptable (150 kV) -Maximum current is still too low (10 kA) -Current risetime also too slow (500 ns)  Can decrease risetime and increase peak current using magnetic pulse compression (MPC) -Five times compression would decrease risetime to 100 ns and increase peak current to 50 kA -Compression factors of >5 times have been demonstrated at STI Designing high-repetition multi-TW CO 2 lasers

3 Ultra-fast CO 2 laser technology on the horizon Ultra-fast CO 2 laser technology on the horizon It will allow to study LWFA in mid-IR spectral domain It will allow to study LWFA in mid-IR spectral domain smaller densities – bigger bubble – higher charge smaller densities – bigger bubble – higher charge Meaningful linear collider LWFA regimes Meaningful linear collider LWFA regimes high-charge LWFA regime good for gamma collider high-charge LWFA regime good for gamma collider Compton driver for 2-TeV gamma collider Compton driver for 2-TeV gamma collider LWFA applications beyond colliders: LWFA applications beyond colliders: seeding/staging studies in big “bubbles” seeding/staging studies in big “bubbles” low emittance regimes: two-color LWFA, all-optical “Trojan Horse” low emittance regimes: two-color LWFA, all-optical “Trojan Horse” Bonus outside LWFA: Bonus outside LWFA: ion acceleration, Thomson sources, … ion acceleration, Thomson sources, … 20Summary

21 Nonlinear post-compression Amplifier Output SPM Focused Spatial Filtered Recompressed Amplifier Output SPM Focused Spatial Filtered Recompressed 1.7 ps 100 fs Kerr effect n = n 0 + n 2 I * US Patent pending S.N. 62/021,725