Advanced approaches to high intensity laser-driven ion acceleration [Elektronische Ressource] / vorgelegt von Andreas Henig

Andreas Henig

Sujets

• Physik

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2010
• Nombre de lectures: 8
• Langue: English
• Poids de l'ouvrage: 19 Mo

Extrait

Advanced Approaches to
High Intensity Laser-Driven
Ion Acceleration
Andreas Henig
Munchen 2010Advanced Approaches to
High Intensity Laser-Driven
Ion Acceleration
Andreas Henig
Dissertation
an der Fakult at fur Physik
der Ludwig{Maximilians{Universit at
Munc hen
vorgelegt von
Andreas Henig
aus Wurzburg
Munc hen, den 18. M arz 2010Erstgutachter: Prof. Dr. Dietrich Habs
Zweitgutachter: Prof. Dr. Toshiki Tajima
Tag der mundlic hen Prufung: 26. April 2010Contents
Contents v
List of Figures ix
Abstract xiii
Zusammenfassung xv
1 Introduction 1
1.1 History and Previous Achievements . . . . . . . . . . . . . . . . . . . 1
1.2 Envisioned Applications . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Theoretical Background 9
2.1 Ionization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Relativistic Single Electron Dynamics . . . . . . . . . . . . . . . . . . 14
2.2.1 Electron Trajectory in a Linearly Polarized Plane Wave . . . . 15
2.2.2 Electron Trajectory in a Circularly Polarized Plane Wave . . . 17
2.2.3 Electron Ejection from a Focussed Laser Beam . . . . . . . . . 18
2.3 Laser Propagation in a Plasma . . . . . . . . . . . . . . . . . . . . . 18
2.4 Laser Absorption in Overdense Plasmas . . . . . . . . . . . . . . . . . 20
2.4.1 Collisional Absorption . . . . . . . . . . . . . . . . . . . . . . 20
2.4.2 Collisionless . . . . . . . . . . . . . . . . . . . . . 21
2.5 Ion Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5.1 Target Normal Sheath Acceleration (TNSA) . . . . . . . . . . 22
2.5.2 Shock Acceleration . . . . . . . . . . . . . . . . . . . . . . . . 26
2.5.3 Radiation Pressure Acceleration / Light Sail / Laser Piston . 27
3 Experimental Methods I - High Intensity Laser Systems 33
3.1 Fundamentals of Ultrashort High Intensity Pulse Generation . . . . . 33vi CONTENTS
3.1.1 The Concept of Mode-Locking . . . . . . . . . . . . . . . . . . 33
3.1.2 Time-Bandwidth Product . . . . . . . . . . . . . . . . . . . . 37
3.1.3 Chirped Pulse Ampli cation . . . . . . . . . . . . . . . . . . . 39
3.1.4 Optical Parametric (OPA) . . . . . . . . . . . . 40
3.2 Laser Systems Utilized for Ion Acceleration Studies . . . . . . . . . . 44
3.2.1 The ATLAS Laser Facility . . . . . . . . . . . . . . . . . . . . 44
3.2.2 The MBI Ti:sapphire System . . . . . . . . . . . . . . . . . . 48
3.2.3 The TRIDENT Laser Facility . . . . . . . . . . . . . . . . . . 50
3.2.4 The VULCAN Laser Facility . . . . . . . . . . . . . . . . . . . 54
4 Experimental Methods II - Targets and Ion Beam Diagnostics 57
4.1 Target Fabrication and Characterization . . . . . . . . . . . . . . . . 57
4.1.1 Microspheres . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.1.2 Ultra-Thin Diamond-Like Carbon (DLC) Foils . . . . . . . . . 60
4.2 Ion Beam Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.2.1 Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4.2.2 Measuring Instruments . . . . . . . . . . . . . . . . . . . . . . 71
5 Shock Acceleration of Ion Beams from Spherical Targets 77
5.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.2 Measured Ion Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.3 PIC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.4 Analytical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.5 Summary/Conclusion/Outlook . . . . . . . . . . . . . . . . . . . . . . 85
6 Enhanced Ion Acceleration in the Transparency Regime 87
6.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.2 Measured Ion Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.3 PIC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.4 Analytical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
6.5 Increasing the Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6.5.1 Measured Ion Beams . . . . . . . . . . . . . . . . . . . . . . . 101
6.6 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 102
7 Radiation Pressure Dominated Acceleration of Ions 103
7.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.2 Measured Ion Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.3 PIC Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108CONTENTS vii
7.4 Summary/Conclusion/Outlook . . . . . . . . . . . . . . . . . . . . . . 111
8 ATLAS-Driven Short Pulse Pumped OPCPA 115
8.1 Motivation for SPP-OPCPA . . . . . . . . . . . . . . . . . . . . . . . 115
8.2 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8.4 Conclusion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . 123
9 Summary, Conclusions and Future Perspectives 125
9.1 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . 125
9.2 Future Plans and Perspectives . . . . . . . . . . . . . . . . . . . . . . 130
9.2.1 Improving the Ion Beam Quality . . . . . . . . . . . . . . . . 130
9.2.2 Paving the Way Towards Applications . . . . . . . . . . . . . 133
Bibliography 137
Publications 163
Acknowledgements 167viiiList of Figures
1.1 Time-integrated CCD camera image of the laser-plasma interaction . 3
1.2 Light sail acceleration dominated by the laser radiation pressure . . . 8
2.1 Distortion of the atomic potential subject to a strong laser eld . . . 11
2.2 Relativistic electron trajectory in a linearly polarized plane wave . . . 16
2.3 trajectory in a circularly polarized plane wave . . 17
2.4 Main mechanisms for ion acceleration from an overdense, opaque target 24
2.5 Radiation Pressure Acceleration (RPA) . . . . . . . . . . . . . . . . . 29
3.1 Intensity pattern resulting fromN = 9 locked modes and a constantM
frequency spectrum. . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2 Kerr-lens mode-locking . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.3 Chirped Pulse Ampli cation (CPA) . . . . . . . . . . . . . . . . . . . 39
3.4 NOPA vs. conventional four-level laser system . . . . . . . . . . . . . 41
3.5 Setup of the ATLAS laser system . . . . . . . . . . . . . . . . . . . . 45
3.6 3rd order autocorrelation trace of the ATLAS laser system . . . . . . 47
3.7 Setup of the MBI laser system . . . . . . . . . . . . . . . . . . . . . . 49
3.8 MBI laser contrast and schematic of the double plasma mirror . . . . 50
3.9 Setup of the TRIDENT laser front end - type 0 . . . . . . . . . . . . 51
3.10 Setup of the laser front end - type 1 . . . . . . . . . . . . 51
3.11 Self-pumped OPA at TRIDENT frontend . . . . . . . . . . . . . . . . 52
3.12 TRIDENT contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.1 Microsphere target fabrication . . . . . . . . . . . . . . . . . . . . . . 58
4.2 Mounted gold microsphere . . . . . . . . . . . . . . . . . . . . . . . . 59
4.3 Cathodic Arc Deposition . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.4 DLC foil thickness characterization via AFM measurements . . . . . 63
4.5 ERDA scheme and obtained DLC depth pro le . . . . . . . . . . . . 65
4.6 Ion induced tracks on CR39 . . . . . . . . . . . . . . . . . . . . . . . 67x LIST OF FIGURES
4.7 Con guration of radiochromic lm (RCF) . . . . . . . . . . . . . . . 68
4.8 MCP detector cross section and high voltage circuit . . . . . . . . . . 70
4.9 Thomson parabola spectrometer setup and resulting ion traces . . . . 71
4.10 Ion energy loss distributions in CR39 . . . . . . . . . . . . . . . . . . 73
4.11 CR39 detector stack . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.1 Experimental setup for ion acceleration from microspheres . . . . . . 78
5.2 Microsphere target imaging . . . . . . . . . . . . . . . . . . . . . . . 79
5.3 Proton beam pro le and spectrum . . . . . . . . . . . . . . . . . . . . 81
5.4 Simulated proton density distribution and origin of most energetic ions 83
6.1 Experimental setup on the rst TRIDENT campaign . . . . . . . . . 90
6.2 TRIDENT double plasma mirror setup . . . . . . . . . . . . . . . . . 91
6.3 Proton beam pro les at di erent energies . . . . . . . . . . . . . . . . 92
6.4 Fully ionized carbon spectra for varying target thicknesses . . . . . . 93
6.5 Electron density and electric eld distribution from 2D PIC simula-
tions of a 10 nm foil target . . . . . . . . . . . . . . . . . . . . . . . . 94
6.6 Spatial distribution of proton and carbon energies from 2D PIC sim-
ulations of a 10 nm foil target . . . . . . . . . . . . . . . . . . . . . . 96
6.7 Maximum ion energies over target thickness observed at increased
20 2 6+intensities of 210 W=cm and a measured carbon C ion spectrum
extending beyond 0.5 GeV . . . . . . . . . . . . . . . . . . . . . . . . 101
6+7.1 Maximum proton and carbon C energies over target thickness for
linearly and circularly polarized irradiation and corresponding elec-
tron spectra measured at the optimum target thickness d = 5:3 nm . . 106
6+7.2 Experimentally observed and simulated proton and carbon C spec-
tra for linear and circular polarized irradiation of a 5.3 nm thickness