Electron heating in sub-ps laser plasma-interaction Lorenzo Cialfi - PowerPoint PPT Presentation

International Conference on High Energy Density Physics Electron heating in sub-ps laser plasma-interaction Lorenzo Cialfi Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

2 Co-authors and Sponsors “ENSURE” project Supercomputing facility (Bologna, IT) Research group (Milano, IT) M. PASSONI L. FEDELI A. FORMENTI V. RUSSO A. PAZZAGLIA A. MAFFINI Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

Co-authors and Sponsors “ENSURE” project Supercomputing facility (Bologna, IT) Research group Experimental campaign (Milano, IT) ( Gwangju , South Korea) M. PASSONI H.W. LEE Il Woo CHOI L. FEDELI A. FORMENTI J. H. SUNG I Jong KIM V. RUSSO A. PAZZAGLIA S.K. LEE Karol JANULEWICZ A. MAFFINI C. H. NAM Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

3 Outline of the presentation I. Introduction  Laser induced ion acceleration  Electron heating: state of the art II. Proposal of scaling law for electron temperature  Different experimental paramenters III. Numerical Campaign  Parametric study IV. Scaling law & Ion acceleration model  Benchmark with experimental results Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

4 Laser driven ion acceleration Laser I > 10 19 𝑋 Τ 𝑑𝑛 2 Interesting features: Duration < ps Compactness Focal spot ~ µm Choerence Tunable energy Taget Thickness: µm/nm Cheaper (?) Foils Potential applications : Required upgrades: Proton imaging/radiography Better performances Material irradiation High repetition rate ( > Hz) Isotope/neutron production Better control over the technique Fast ignition Hadrontherapy A. Macchi, M. Borghesi, M. Passoni, Rev. Mod. Phys., 85 751 (2013) Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

5 Target Normal Sheath Acceleration (TNSA) Electron heating Electron expansion Charge separation Many acceleration mechanisms Target Normal Sheath Ion acceleration Acceleration (TNSA) Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

5 Target Normal Sheath Acceleration (TNSA) 𝑼 𝒇 Electron heating Electron expansion Charge separation Many acceleration mechanisms 𝑭 𝒏𝒃𝒚 Target Normal Sheath Ion acceleration Acceleration (TNSA) Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

6 Modelling TNSA Possible approaches: Quasi stationary models β φ ∗ ,Ϛ 𝑓 φ ∗ − 1 + 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 𝑎 𝑗 𝑙 𝑐 𝑈 𝐽 φ ∗ ,Ϛ 𝑓 Ϛ+φ∗ M. Passoni and M. Lontano, Phys. Rev. Lett., vol. 101, p. 115001 (2008). Fluid models 𝑓 𝑚𝑜 2 τ + τ 2 + 1 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 2𝑎 𝑗 𝑙 𝑐 𝑈 P. Mora, Physical Review Letters, V 90 N 18 (2003) Hybrid models 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 𝑎 𝑗 𝑙 𝑐 𝑈 𝑓 𝑔(𝑟) B. J. Albright, et al., Physical Review Letters, 97:115002 (2006). Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

6 Modelling TNSA Electron temperature  key parameter Possible approaches: 𝐉 𝟏.𝟔 Quasi stationary models Experiments I β φ ∗ ,Ϛ 𝑓 φ ∗ − 1 + 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 𝑎 𝑗 𝑙 𝑐 𝑈 𝐽 φ ∗ ,Ϛ 𝑓 Ϛ+φ∗ 𝑓 [KeV] M. Passoni and M. Lontano, Phys. Rev. Lett., vol. 101, p. 𝐉 𝟏.𝟒 115001 (2008). 𝑈 Fluid models 𝑓 𝑚𝑜 2 τ + τ 2 + 1 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 2𝑎 𝑗 𝑙 𝑐 𝑈 𝐽λ 2 [W cm −2 µm] P. Mora, Physical Review Letters, V 90 N 18 (2003) P. Gibbon; Short Pulse Laser Interaction Hybrid models with Matter; Imperial college press (2005) 𝐹 𝑛𝑏𝑦 (𝑗𝑝𝑜𝑡) = 𝑎 𝑗 𝑙 𝑐 𝑈 𝑓 𝑔(𝑟) Laser intensity dependence B. J. Albright, et al., Physical Review Letters, 97:115002 Other dependences ? (2006). Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

7 Electron temperature − 3 𝑓 ∝ 𝐽 1/3 𝑢 1/6  not efficient for Collisional heating  e-i collisions  ν 𝑓𝑗 ∝ 𝑎𝑜 𝑓 𝑈 2 ln Λ , 𝑈 𝑓 high intensities and short pulses 𝑓 ∝ 𝐽λ 2 1/3  efficient for long pulses ( ~ ps) and plasma gradients (µm) Resonance heating  𝑈 Ultra-intense laser (I > 10 18 𝑋/𝑑𝑛 2 ) + Sharp-edged micrometric solid targets jxB heating Brunel effect Collisionless 2 𝑏 0 Ponderomotive scaling 2 Interaction efficiency 1 + 𝐽λ(µ𝑛) 2 1 2 𝑡𝑗𝑜 2 θ 1/2 − 1 𝑡𝑗𝑜θ 1 + 𝑔 2 𝑏 0 𝑈 𝑓 𝑁𝑓𝑊 = 0.511 1.37 ∙ 10 18 − 1 η = π𝑏 0 𝑑𝑝𝑡θ Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

7 Electron temperature − 3 𝑓 ∝ 𝐽 1/3 𝑢 1/6  not efficient for Collisional heating  e-i collisions  ν 𝑓𝑗 ∝ 𝑎𝑜 𝑓 𝑈 2 ln Λ , 𝑈 𝑓 high intensities and short pulses 𝑓 ∝ 𝐽λ 2 1/3  efficient for long pulses ( ~ ps) and plasma gradients (µm) Resonance heating  𝑈 Ultra-intense laser (I > 10 18 𝑋/𝑑𝑛 2 ) + Sharp-edged micrometric solid targets jxB heating Brunel effect Collisionless 2 /2 𝑏 0 Ponderomotive scaling Interaction efficiency 1 + 𝐽λ(µ𝑛) 2 1 2 𝑡𝑗𝑜 2 θ 1/2 − 1 𝑡𝑗𝑜θ 1 + 𝑔 2 𝑏 0 𝑈 𝑓 𝑁𝑓𝑊 = 0.511 1.37 ∙ 10 18 − 1 η = π𝑏 0 𝑑𝑝𝑡θ Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

8 Micrometric plain solid targets: scaling law proposal Brunel effect  jxB heating  interaction efficiency  hp: No angular dependence 𝑓 𝛽 η 𝐹 𝑚𝑏𝑡𝑓𝑠  Ponderomotive scaling  𝑈 𝑂 𝑓 Hp: combined heating 1 + 𝑏 02 2 𝑡𝑗𝑜 2 θ −1 ∙ tan θ 2 −1 𝑈 𝑓 [𝑁𝑓𝑊] = 0.511 ∙ 𝐷 1 𝑏 0 , 𝑞𝑝𝑚 ∙ + 0.511 ∙ 𝐷 2 𝑏 0 , 𝑞𝑝𝑚 ∙ 1 + 2𝑏 0 𝑫 𝟐 𝑏 0 , 𝑞𝑝𝑚 & 𝑫 𝟑 𝑏 0 , 𝑞𝑝𝑚 : ?  Numerical simulations  Temperature fit Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

Particle In Cell (PIC) simulations: Electron temperature 9 Target Laser Composition : 𝐵𝑚 9+ + 𝐼 + ( contaminants ) Intensity: 1.5 < 𝑏 0 < 15 Incidence angle : 0 – 15 – 30 – 45 - 60° Thickness : 0,5 µm and 50 nm contaminants Density: 80 𝑜 𝑑 and 4 𝑜 𝑑 Polarization: P-, C-, S- 2D results: C polarization 2D results: P polarization Electron Temperature (MeV) Electron Temperature (MeV) 3,5 2,00 a 0 = 15 a 0 = 5 a 0 = 15 a 0 = 5 1,75 3,0 a 0 = 10 a 0 = 3 a 0 = 10 a 0 = 3 1,50 a 0 = 7.5 a 0 = 1.5 a 0 =7.5 a 0 = 1.5 2,5 1,25 2,0 1,00 1,5 0,75 1,0 0,50 0,5 0,25 0,0 0,00 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Incidence angle (°) Incidence angle (°) Angular dependence: P and C polarization S polarization (requires 3D simulations) constant temperature Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

Particle In Cell (PIC) simulations: Electron temperature 10 Target Laser Composition : 𝐵𝑚 9+ + 𝐼 + ( contaminants ) Intensity: 1.5 < 𝑏 0 < 15 Incidence angle : 0 – 15 – 30 – 45 - 60° Thickness : 0,5 µm and 50 nm contaminants Density: 80 𝑜 𝑑 and 4 𝑜 𝑑 Polarization: P-, C-, S- 3D results Electron Temperature (MeV) 1,6 P pol a 0 =10 C pol a 0 =10 1,4 S pol a 0 =10 C pol a 0 = 5 1,2 C pol a 0 =15 C pol a 0 = 3 C pol a 0 =14.4 1,0 0,8 0,6 0,4 0,2 0,0 0 10 20 30 40 50 Incidence angle (°) Angular dependence: P and C polarization S polarization (requires 3D simulations) constant temperature Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

11 Estimation of 𝑫 𝟐 and 𝑫 𝟑 coefficients C polarization P polarization C 2 C 2 0,5 1,0 C 1 Fit coefficients C 1 Fit coefficients 0,4 0,8 0,3 0,6 0,2 0,4 0,1 0,2 0,0 0,0 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 16 Normalized laser amplitude (a 0 ) Normalized laser amplitude (a 0 ) Numerical fit: 𝑈 𝑓 = 𝐷 1 𝑏 0 , 𝑞𝑝𝑚 𝑈 𝑓 (𝐊x𝐂) + 𝐷 2 𝑏 0 , 𝑞𝑝𝑚 𝑈 𝑓 (Brunel) 𝐷 1 , 𝐷 2 constant for 𝑏 0 > 3 𝐷 2 (pol S) = 0 (no Brunel) 𝐷 1 (pol S) = 𝐷 1 (pol P) Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

11 Estimation of 𝑫 𝟐 and 𝑫 𝟑 coefficients C polarization P polarization C 2 C 2 0,5 1,0 C 1 Fit coefficients C 1 Fit coefficients 0,4 0,8 0,3 0,6 0,2 0,4 0,1 0,2 0,0 0,0 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14 16 Normalized laser amplitude (a 0 ) Normalized laser amplitude (a 0 ) Numerical fit: 𝑈 𝑓 = 𝐷 1 𝑏 0 , 𝑞𝑝𝑚 𝑈 𝑓 (𝐊x𝐂) + 𝐷 2 𝑏 0 , 𝑞𝑝𝑚 𝑈 𝑓 (Brunel) 𝐷 1 , 𝐷 2 constant for 𝑏 0 > 3 𝐷 2 (pol S) = 0 (no Brunel) 𝐷 1 (pol S) = 𝐷 1 (pol P) Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016

12 Numerical results: electron trajectories 15 µm thick Al 0.5 µm thick Al Interaction: I. Normal oscillations II. Kick along the laser direction III. Injection at 2 ω Thicker targets: Similar temperatures (20% decrease) No 𝑓 − recirculation  less confinement Nome relatore Lorenzo Cialfi ICHEDP2016 25/09/2016