Shao Investigations on rf breakdown phenomenon in high gradient accelerating structures

1. Auflage 2018
ISBN: 978-981-10-7926-9
Verlag: Springer Nature Singapore
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 142 Seiten

Reihe: Springer Theses

This book mainly focuses on the experimental research of rf breakdown and field emission with novel methods, including triggering rf breakdown with high intensity laser and pin-shaped cathodes as well as locating field emitters with a high resolution in-situ imaging system. With these methods, this book has analyzed the power flow between cells during rf breakdown, observed the evolution of field emission during rf conditioning and the dependence of field emission on stored energy, and studied the field emitter distribution and origination. The research findings greatly expand the understanding of rf breakdown and field emission, which will in turn benefit future study into electron sources, particle accelerators, and high gradient rf devices in general. 

Jiahang Shao received his Bachelor's degree in Engineering from the Department of Electronic Engineering at Tsinghua University, China in 2011. He obtained his Ph.D. in Engineering from the Department of Engineering Physics at the same university in July 2016, where his major research project in Prof. Huaibi Chen's group was the experimental study of rf breakdown and field emission in high gradient accelerating structures. Currently, he is a postdoctoral appointee working with Prof. Wei Gai at Argonne National Laboratory, USA, continuing his study on field emission and conducting research on wakefield generation by intense electron beam.

Autoren/Hrsg.

Shao, Jiahang

Inhaltsverzeichnis

1;Supervisor’s Foreword;7
2;Preface;8
3;Acknowledgements;10
4;Contents;12
5;1 Introduction;1
5.1;1.1 Application of High Gradient Accelerating Structures;14
5.1.1;1.1.1 Compact Electron-Positron Collider;15
5.1.2;1.1.2 Compact Light Source;16
5.1.3;1.1.3 Photocathode rf Gun;17
5.1.4;1.1.4 Industry/Medical Accelerator;18
5.2;1.2 rf Breakdown;19
5.2.1;1.2.1 Phenomenon;20
5.2.2;1.2.2 Impact;21
5.2.3;1.2.3 Research Status;23
5.3;1.3 Field Emission;30
5.3.1;1.3.1 Phenomenon;30
5.3.2;1.3.2 Research Status;32
5.4;1.4 Main Content and Innovation;35
5.5;References;37
6;2 Experimental Research of Laser-Triggered rf Breakdown;1
6.1;2.1 Physical Background;42
6.2;2.2 Experimental Setup;43
6.2.1;2.2.1 S-Band Photocathode rf Gun;43
6.2.2;2.2.2 Diagnostics;44
6.3;2.3 Experiment Observation;45
6.3.1;2.3.1 Surface Damage Test;45
6.3.2;2.3.2 High Power Test;47
6.4;2.4 Basic Analysis;51
6.4.1;2.4.1 Modes Evolution;51
6.4.2;2.4.2 Frequency Detuning;56
6.4.3;2.4.3 Time Structure of rf Breakdown Current;56
6.5;2.5 Advanced Analysis with an Equivalent Circuit Model;58
6.5.1;2.5.1 Equivalent Circuit Model;58
6.5.2;2.5.2 Basic Equations;59
6.5.3;2.5.3 Parameters;63
6.5.4;2.5.4 Analysis;65
6.5.5;2.5.5 Discussion;67
6.6;2.6 Summary;70
6.7;References;70
7;3 Experimental Research of Pin Cathode;72
7.1;3.1 L-Band Photocathode rf Gun Test Stand;72
7.1.1;3.1.1 L-Band Photocathode rf Gun;72
7.1.2;3.1.2 Test Stand;77
7.2;3.2 Evolution of Field Emission During rf Conditioning;79
7.2.1;3.2.1 rf Conditioning of Pin Cathodes;80
7.2.2;3.2.2 Field Emission Measurement;82
7.2.3;3.2.3 Surface Examination;85
7.2.4;3.2.4 Discussion;86
7.3;3.3 Field Emission Dependence on Stored Energy;88
7.3.1;3.3.1 Field Emission Current Measurement;88
7.3.2;3.3.2 Dynamics of Field Emission Current;92
7.3.3;3.3.3 Possible Mechanisms;97
7.3.4;3.3.4 Discussion;102
7.4;3.4 Summary;103
7.5;References;103
8;4 In-situ High Resolution Field Emission Imaging;106
8.1;4.1 Imaging Method;106
8.1.1;4.1.1 Difficulties;106
8.1.2;4.1.2 Solution;108
8.2;4.2 Dynamics Simulation;110
8.2.1;4.2.1 Imaging Properties;110
8.2.2;4.2.2 Electron Distribution;112
8.2.3;4.2.3 Emission Phase Selection;112
8.2.4;4.2.4 Beam Line Optimization;114
8.3;4.3 Experiment Preparation;122
8.3.1;4.3.1 New Cathode;122
8.3.2;4.3.2 Beam Line Upgrading;123
8.4;4.4 High Resolution Field Emission Imaging Experiment;126
8.4.1;4.4.1 In-situ High Resolution Field Emitter Observation;127
8.4.2;4.4.2 Field Enhancement Factor Measurement;129
8.4.3;4.4.3 Surface Analysis;133
8.5;4.5 Summary;135
8.6;References;135
9;5 Summary and Future Study;137
10;Appendix A Calculating the Electric Field on the Pin Cathode;140