LWFA with high power fewcycle midIR lasers Daniel

Contributors ELI-ALPS (Szeged, Hungary) INRS (Varennes, Québec, Canada) Christos KAMPERIDIS Francois LÉGARÉ Daniel PAPP

The SYLOS laser system at ELIALPS ELI-ALPS SYLOS 1 880 nm, 1 k. Hz,

PIC simulations Parametic study with EPOCH 2 D Paraxial focusing formalism Gaussian laser pulse

5 TW λ scan Laser parameters Wavelength (um) 0. 88 1. 8 3. 2

5 TW - strong λ effect in efficiency and charge Helium plasma parameters λlaser

15 TW λ scan Laser parameters λ (μm) 0. 88 1. 8 3. 2

15 TW λ scan Laser parameters and electron energies λlaser (um) 0. 88 1.

15 TW λ = 3. 2 μm 384 m. J Density scan ne =

Conclusions Longer λ improves efficiency and bunch charge for few-cycle LWFA 5 TW Quasi-monoenergetic

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LWFA with high power, few-cycle mid-IR lasers* Daniel Papp 26 th September 2017, La Biodola 2017 EAAC * The ELI-ALPS project (GINOP-2. 3. 6 -15 -2015 -00001) is supported by the European Union and co-financed by the European Regional Development Fund.

Contributors ELI-ALPS (Szeged, Hungary) INRS (Varennes, Québec, Canada) Christos KAMPERIDIS Francois LÉGARÉ Daniel PAPP (presenter) Vicent GRUSON Imperial College (London, UK) CELIA (Bordeaux, France) Zulfikar NAJMUDIN Eric CORMIER Jonathan WOOD

Motivation – few-cycle lasers

The SYLOS laser system at ELIALPS ELI-ALPS SYLOS 1 880 nm, 1 k. Hz, 55 m. J, 9 fs full-OPCPA (Budriunas Opt. Exp. 2017) Factory Acceptance Test earlier this year ELI-ALPS SYLOS 2 A 35 m. J, <7 fs, 5 TW Upgrade contracted ELI-ALPS SYLOS-2 B Expected 100 m. J, 5 fs, 20 TW Proposed TW Mid-IR laser at ELI-ALPS Any advantages of longer wavelength for LWFA? λ scaling into mid-IR? PIC simulation parametric study, by λ-scaling SYLOS parameters

PIC simulations Parametic study with EPOCH 2 D Paraxial focusing formalism Gaussian laser pulse (temporally and spatially) Flat plasma profile with 100 μm ramps Initially neutral He gas with ionization Laser-to-electron efficiency calculated from laser EM field energy and total electron bunch energy Bunch charge inferred from laser pulse energy, efficiency, and average electron energy

5 TW λ scan Laser parameters Wavelength (um) 0. 88 1. 8 3. 2 10 Energy (m. J) 35 72 128 400 Duration (fs) 7. 0 14. 4 25. 6 80 w 0 (μm) 6. 4 13 23. 1 72 1. 0 e 19 2. 4 e 18 7. 7 e 17 7. 5 e 16 104 213 378 1183 2. 9 e 19 6. 9 e 18 2. 2 e 17 Intensity (W/cm 2) ZR (μm) ne (cm-3) „SYLOS 2 A” laser parameters scaled by λ Kept constant: • # of laser cycles = 2. 4 • Laser power = 5 TW • w 0 = 3 cτ • Tight focusing with same f/# • ne/ncr = 0. 02, λpl/w 0 =1 • a 0 = 2. 4

5 TW λ = 0. 88 μm 35 m. J He ne = 2. 9× 1019 cm-3 2 D electron density map x_px electron phase space

5 TW λ = 0. 88 μm 35 m. J He ne = 2. 9× 1019 cm-3 2 D electron density map x_px electron phase space 1 st bunch ~10 p. C (from 2 nd bubble)

5 TW λ = 1. 8 μm 72 m. J He ne = 6. 9× 1018 cm-3 2 D electron density map x_px electron phase space

5 TW λ = 1. 8 μm 72 m. J He ne = 6. 9× 1018 cm-3 2 D electron density map x_px electron phase space 1 st bunch of He I + II : ~ 50 p. C

5 TW λ = 3. 2 μm 128 m. J He ne = 2. 2× 1018 cm-3 2 D electron density map x_px electron phase space

5 TW λ = 3. 2 μm 128 m. J He ne = 2. 2× 1018 cm-3 2 D electron density map x_px electron phase space 1 st bunch of He I + II : ~ 242 p. C

5 TW λ = 10 μm 400 m. J He ne = 2. 2× 1017 cm-3 2 D electron density map x_px electron phase space

5 TW λ = 10 μm 400 m. J He ne = 2. 2× 1017 cm-3 2 D electron density map x_px electron phase space No He I injected in first bubble 1 st bunch of He II : 730 p. C

5 TW - strong λ effect in efficiency and charge Helium plasma parameters λlaser (um) 0. 88 1. 8 3. 2 10 Energy (m. J) 35 72 128 400 Duration (fs) 7 14. 4 25. 6 80 w 0 (μm) 6. 4 13 23. 1 72. 2 Wbunch [Me. V] 15 61 52 48 Wmax [Me. V] 56 68 64 60 Efficiency 0. 43% 4. 2% 9. 9% 8. 8% 10 50 242 730 Charge in 1 st bunch (p. C) 880 nm case is „marginal”, no injection in first bubble Better charge/efficiency for 1. 8 -10 μm Distinct quasi-monoenergetic electron bunch Energy decreases with λ No injection at ne = 0. 01 nc

15 TW λ scan Laser parameters λ (μm) 0. 88 1. 8 3. 2 10 Energy (m. J) 105 216 384 1200 Duration (fs) 7. 0 14. 4 25. 6 80 w 0 (μm) 6. 4 13 23. 1 72 3. 0 e 19 7. 3 e 18 2. 3 e 17 104 213 378 1183 2. 9 e 19 6. 9 e 18 2. 2 e 17 Intensity (W/cm 2) ZR (μm) ne (cm-3) „SYLOS 2 B-like” (105 m. J/7 fs instead of 100 m. J/5 fs) and λ-scaled parameters Kept constant: • Laser power = 15 TW • ne/ncr = 0. 02, λpl/w 0 =1 (as 5 TW cases) • Tight focusing with same f/# (as 5 • # of laser cycles = 2. 4 (as 5 TW cases) • w 0 = 3 cτ (as 5 TW cases) • a 0 = 4. 5

15 TW λ = 0. 88 μm 105 m. J He ne = 2. 9× 1019 cm-3 2 D electron density map x_px electron phase space

15 TW λ = 0. 88 μm 105 m. J He ne = 2. 9× 1019 cm-3 2 D electron density map x_px electron phase space 1 st bunch of He I + II : ~ 0. 43 n. C

15 TW λ = 1. 8 μm 216 m. J He ne = 6. 9× 1018 cm-3 2 D electron density map x_px electron phase space

15 TW λ = 1. 8 μm 216 m. J He ne = 6. 9× 1018 cm-3 2 D electron density map Continuous injection x_px electron phase space 1 st bunch of He I + II : ~ 1. 3 n. C

15 TW λ = 3. 2 μm 384 m. J He ne = 2. 2× 1018 cm-3 2 D electron density map x_px electron phase space

15 TW λ = 3. 2 μm 384 m. J He ne = 2. 2× 1018 cm-3 2 D electron density map Continuous injection x_px electron phase space 1 st bunch of He I + II : ~ 3. 5 n. C

15 TW λ = 10 μm 1. 2 J He ne = 2. 2× 1017 cm-3 2 D electron density map x_px electron phase space

15 TW λ = 10 μm 1. 2 J He ne = 2. 2× 1017 cm-3 2 D electron density map Continuous injection x_px electron phase space 1 st bunch of He I + II : ~ 10. 9 n. C

15 TW λ scan Laser parameters and electron energies λlaser (um) 0. 88 1. 8 3. 2 10 Energy (m. J) 105 216 384 1200 Duration (fs) 7 14. 4 25. 6 80 w 0 (μm) 6. 4 13 23. 1 72. 2 Wbunch [Me. V] 48 59 48 43 Wmax [Me. V] 109 104 95 80 Observations • Continuous injection, worse beam quality than at 5 TW • Max electron energy decreasing with λ

15 TW λ scan Laser parameters and electron energies λlaser (um) 0. 88 1. 8 3. 2 10 Energy (m. J) 105 216 384 1200 Duration (fs) 7 14. 4 25. 6 80 w 0 (μm) 6. 4 13 23. 1 72. 2 Wbunch [Me. V] 48 59 48 43 Wmax [Me. V] 109 104 95 80 Efficiency 20% 37% 44% 39% Charge (n. C) 0. 43 1. 3 3. 5 10. 9 Observations • Continuous injection, worse beam quality than at 5 TW • Max electron energy decreasing with λ • Ridiculously high efficiency and charge

15 TW λ = 3. 2 μm 384 m. J Density scan ne = 0. 015 nc ne = 0. 020 nc

15 TW λ = 3. 2 μm 384 m. J Density scan ne = 0. 015 nc 85 (145 max) Me. V, 1. 5 n. C No injection in first bubble at ne = 0. 010 nc ne = 0. 020 nc 48 (95 max) Me. V, 3. 5 n. C

Conclusions Longer λ improves efficiency and bunch charge for few-cycle LWFA 5 TW Quasi-monoenergetic features 15 TW Very high inferred efficiency (and bunch charge) Continuous injection Beam quality should be improved by adjusting laser/plasma parameters Prospective use: - Irradiation applications - Inverse Compton x-ray source

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