6 Relativistic Laser Plasma Interactions . . . . . . . . . . . . . . . . . . . . . . . . 203
6.1
Charge Separation in Low-Density Plasma . . . . . . . . . . . . . . . . . 203
6.1.1
Charge Separation by Photon Force . . . . . . . . . . . . . . . . 203
6.1.2
Wake Field Generation and Energy Deposition . . . . . . . 205
6.2
Laser Propagation in Plasmas . . . . . . . . . . . . . . . . . . . . . . . . . . 207
6.2.1
Relativistic Transparency . . . . . . . . . . . . . . . . . . . . . . . 207
6.2.2
Higher Harmonic Generation (HHG) . . . . . . . . . . . . . . . 209
6.2.3
Electrostatic Field Excitation by vxB Force . . . . . . . . . . 212
6.2.4
Density Bunching Current . . . . . . . . . . . . . . . . . . . . . . 213
6.2.5
Simulation for a 0 ¼ 10 in Low Density . . . . . . . . . . . . . 214
6.3
Ponderomotive Force in Relativistic Field . . . . . . . . . . . . . . . . . . 217
6.3.1
PM Force by Electrostatic Wave . . . . . . . . . . . . . . . . . . 219
6.3.2
Validity of Electrons in Plasmas Assumption . . . . . . . . . 219
6.4
Relativistic Raman Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . 220
6.5
Relativistic Self-Focusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
6.5.1
Self-Focusing Condition . . . . . . . . . . . . . . . . . . . . . . . . 223
6.5.2
Strong Laser Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
6.5.3
Difference of 2D and 3D Focusing . . . . . . . . . . . . . . . . 225
6.5.4
Frequency Shifts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
6.5.5
Filamentation Instability . . . . . . . . . . . . . . . . . . . . . . . . 226
6.6
Relativistic Skin Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
6.7
JxB Force and Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
6.8
Moving Mirror Model and Higher Harmonic Generation
from Solid Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
7 Relativistic Laser and Solid Target Interactions . . . . . . . . . . . . . . . . 239
7.1
Pre-formed Plasma in Laser-Solid Interaction . . . . . . . . . . . . . . . 239
7.1.1
Pedestal of Laser Pulse . . . . . . . . . . . . . . . . . . . . . . . . . 239
7.1.2
Model Experiments with Controlled Pre-formed
Plasmas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
7.2
Laser Absorption at Solid Targets . . . . . . . . . . . . . . . . . . . . . . . 244
7.3
Absorption Enhancement by Hot Electron Re-circulation . . . . . . . 248
7.4
Hole Boring by Ponderomotive Force . . . . . . . . . . . . . . . . . . . . 252
7.4.1
Density Dependence of Hole Boring . . . . . . . . . . . . . . . 254
7.5
Laser Interaction in Long Pre-formed Plasmas . . . . . . . . . . . . . . 255
7.6
Absorption Efficiency Based on Conservation Laws . . . . . . . . . . 260
7.7
Enhanced Coupling with Foam Layered Targets . . . . . . . . . . . . . 263
7.7.1
Experimental Result . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
7.8
Efficient Absorption in Structured Targets . . . . . . . . . . . . . . . . . 273
7.8.1
Micro-pillar Array Targets . . . . . . . . . . . . . . . . . . . . . . 273
7.8.2
Nano-pillar Array Target . . . . . . . . . . . . . . . . . . . . . . . 275
7.8.3
Micro-tube Plasma Lenses . . . . . . . . . . . . . . . . . . . . . . 277
7.8.4
Common Rule of Better Coupling . . . . . . . . . . . . . . . . . 279
xvi
Contents
6.1
Charge Separation in Low-Density Plasma . . . . . . . . . . . . . . . . . 203
6.1.1
Charge Separation by Photon Force . . . . . . . . . . . . . . . . 203
6.1.2
Wake Field Generation and Energy Deposition . . . . . . . 205
6.2
Laser Propagation in Plasmas . . . . . . . . . . . . . . . . . . . . . . . . . . 207
6.2.1
Relativistic Transparency . . . . . . . . . . . . . . . . . . . . . . . 207
6.2.2
Higher Harmonic Generation (HHG) . . . . . . . . . . . . . . . 209
6.2.3
Electrostatic Field Excitation by vxB Force . . . . . . . . . . 212
6.2.4
Density Bunching Current . . . . . . . . . . . . . . . . . . . . . . 213
6.2.5
Simulation for a 0 ¼ 10 in Low Density . . . . . . . . . . . . . 214
6.3
Ponderomotive Force in Relativistic Field . . . . . . . . . . . . . . . . . . 217
6.3.1
PM Force by Electrostatic Wave . . . . . . . . . . . . . . . . . . 219
6.3.2
Validity of Electrons in Plasmas Assumption . . . . . . . . . 219
6.4
Relativistic Raman Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . 220
6.5
Relativistic Self-Focusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
6.5.1
Self-Focusing Condition . . . . . . . . . . . . . . . . . . . . . . . . 223
6.5.2
Strong Laser Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
6.5.3
Difference of 2D and 3D Focusing . . . . . . . . . . . . . . . . 225
6.5.4
Frequency Shifts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
6.5.5
Filamentation Instability . . . . . . . . . . . . . . . . . . . . . . . . 226
6.6
Relativistic Skin Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
6.7
JxB Force and Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
6.8
Moving Mirror Model and Higher Harmonic Generation
from Solid Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
7 Relativistic Laser and Solid Target Interactions . . . . . . . . . . . . . . . . 239
7.1
Pre-formed Plasma in Laser-Solid Interaction . . . . . . . . . . . . . . . 239
7.1.1
Pedestal of Laser Pulse . . . . . . . . . . . . . . . . . . . . . . . . . 239
7.1.2
Model Experiments with Controlled Pre-formed
Plasmas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
7.2
Laser Absorption at Solid Targets . . . . . . . . . . . . . . . . . . . . . . . 244
7.3
Absorption Enhancement by Hot Electron Re-circulation . . . . . . . 248
7.4
Hole Boring by Ponderomotive Force . . . . . . . . . . . . . . . . . . . . 252
7.4.1
Density Dependence of Hole Boring . . . . . . . . . . . . . . . 254
7.5
Laser Interaction in Long Pre-formed Plasmas . . . . . . . . . . . . . . 255
7.6
Absorption Efficiency Based on Conservation Laws . . . . . . . . . . 260
7.7
Enhanced Coupling with Foam Layered Targets . . . . . . . . . . . . . 263
7.7.1
Experimental Result . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
7.8
Efficient Absorption in Structured Targets . . . . . . . . . . . . . . . . . 273
7.8.1
Micro-pillar Array Targets . . . . . . . . . . . . . . . . . . . . . . 273
7.8.2
Nano-pillar Array Target . . . . . . . . . . . . . . . . . . . . . . . 275
7.8.3
Micro-tube Plasma Lenses . . . . . . . . . . . . . . . . . . . . . . 277
7.8.4
Common Rule of Better Coupling . . . . . . . . . . . . . . . . . 279
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