Laser-driven proton beams are still in their infancy but already have some outstanding attributes compared to those produced in conventional accelerators. One such attribute is the typically low beam emittance. This allows excellent resolution in imaging applications like proton radiography. This thesis describes a novel imaging technique - the proton streak camera - that the author developed and first used to measure both the spatial and temporal evolution of ultra-strong electrical fields in laser-driven plasmas. Such investigations are of paramount importance for the understanding of laser-plasma interactions and, thus, for optimization of laser-driven particle acceleration. In particular, the present work investigated micrometer-sized spherical targets after laser irradiation. The confined geometry of plasmas and fields was found to influence the kinetic energy and spatial distribution of accelerated ions. This could be shown both in experimental radiography images and and in numerical simulations, one of which was selected for the cover page of Physical Review Letters.
Author(s): Thomas Sokollik
Series: Springer Theses
Edition: 1st Edition.
Publisher: Springer
Year: 2011
Language: English
Pages: 138
Cover......Page 1
Investigations of Field Dynamics in Laser Plasmas with Proton Imaging......Page 4
ISBN 9783642150395......Page 5
Supervisor’s Foreword......Page 6
Acknowledgments......Page 10
Contents......Page 12
1 Introduction......Page 16
References......Page 18
Part I Basics......Page 20
2.1…Mathematical Description......Page 22
2.2…Single Electron Interaction......Page 25
2.3…Ponderomotive Force......Page 27
References......Page 29
3.1…Light Propagation in Plasmas......Page 32
3.2…Debye Length......Page 35
3.3…Plasma Expansion......Page 36
References......Page 38
4.1.1 Resonance Absorption......Page 40
4.1.2 Brunel Absorption (Vacuum Heating)......Page 42
4.1.3 Ponderomotive Acceleration, Hole Boring and j x B Heating......Page 43
4.2…Target Normal Sheath Acceleration......Page 44
4.3 Alternative Acceleration Mechanisms......Page 47
References......Page 49
5.1…Ti:Sa Laser System......Page 52
5.2…Nd:glass Laser System......Page 55
5.3…Synchronization......Page 56
References......Page 59
Part II Proton Beam Characterization......Page 60
6.1…Thomson Spectrometer......Page 62
6.2…Quasi-Monoenergetic Deuteron Bursts......Page 65
6.3…Irregularities of the Thomson Parabolas......Page 66
References......Page 67
7 Beam Emittance......Page 70
7.1…Virtual Source......Page 71
7.2…Measurement of the Beam Emittance......Page 72
References......Page 74
8.1…Energy Dependent Measurement of Pinhole Projections......Page 76
8.2…Shape of the Proton Beam......Page 79
References......Page 82
Part III Proton Imaging......Page 84
9.1…Principle Experimental Setup......Page 86
9.2…Gated Multi-Channel Plates......Page 88
9.3…Time Resolution......Page 89
References......Page 90
10.1…Experimental Setup......Page 92
10.2…2D-Proton Images......Page 93
References......Page 96
11 Mass-Limited Targets......Page 98
11.1…Experimental Setup......Page 99
11.2…Water Droplet Generation......Page 100
11.3…Proton Images of Irradiated Water Droplets......Page 102
11.4…Three-dimensional Particle Tracing......Page 106
References......Page 108
12.1…The Proton Streak Camera......Page 112
12.2…Streaking Transient Electric Fields......Page 114
12.3…Fitting Calculations......Page 116
12.4…Particle Tracing......Page 118
References......Page 121
13 Summary and Outlook......Page 122
Reference......Page 123
Part IV Appendix......Page 124
14 Zernike Polynomials......Page 126
ReferenceReference......Page 127
15 Gated MCPs......Page 128
Education and Work History......Page 132
List of Publications......Page 133
Index......Page 136
