UNIVERSITY OF CALIFORNIA, IRVINE Fast Ions and Shear Alfvén Waves DISSERTATION submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Physics By Yang Zhang Dissertation Committee: Professor William W. Heidbrink, Co-chair Professor Roger McWilliams, Co-chair Professor Zhihong Lin 2008 ©2008 Yang Zhang The dissertation of Yang Zhang is approved and is acceptable in quality and form for publication on microfilm ________________________ ________________________ ________________________ Committee Chair University of California, Irvine 2008 ii DEDICATION To my wife Lily, and my parents, for their love and support. The LORD is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower. Psalm 18:2 iii TABLE OF CONTENTS CONTENTS ………………………………………………………………………………….Page TABLE OF CONTENTS .........................................................................................................iv LIST OF FIGURES .................................................................................................................vi LIST OF TABLES....................................................................................................................ix LIST OF SYMBOLS.................................................................................................................x ACKNOWLEDGMENTS......................................................................................................xiii CURRICULUM VITAE ......................................................................................................... xv ABSTRACT OF THE DISSERTATION..............................................................................xvii CHAPTER 1 INTRODUCTION...............................................................................................1 1.1 FAST IONS AND ALFVÉN WAVES IN PLASMAS .................................................................. 1 1.2 FAST -ION TRANSPORT PROJECT AT UC IRVINE ................................................................. 3 1.3 PREVIOUS CLASSICAL FAST -ION TRANSPORT STUDY ....................................................... 4 1.4 SHEAR ALFVÉN WAVES IN THE UPGRADED LAPD........................................................... 6 1.5 CONTENT OF THESIS ....................................................................................................... 8 CHAPTER 2 EXPERIMENTAL APPARATUSES ................................................................12 2.1 BASIC PLASMA SCIENCE FACILITY AT UCLA—THE UPGRADED LAPD...........................12 2.2 IRVINE ELECTRON -POSITRON CHAMBER ........................................................................17 2.3 IRVINE FAST -ION SOURCES .............................................................................................20 2.3.1 Thermionic Lithium Aluminosilicate Ion Sources .....................................................22 2.3.2 3-cm RF Ion Source Modification............................................................................47 2.4 SHEAR ALFVÉN WAVES ANTENNAS ................................................................................48 2.5 DIAGNOSTIC TOOLS .......................................................................................................49 2.5.1 Collimated/Gridded Fast-ion Analyzers...................................................................50 2.5.2 B-dot Probes for Wave Magnetic Field ....................................................................59 CHAPTER 3 FAST-ION DOPPLER SHIFTED CYCLOTRON RESONANCE WITH SHEAR ALFVÉN WAVES .....................................................................................................62 3.1 RESONANCE THEORY .....................................................................................................63 3.2 SAW DISPERSION RELATION ..........................................................................................65 3.3 RESONANCE ORBIT SIMULATION CODE ..........................................................................66 3.3.1 Single particle simulation........................................................................................66 3.3.2 Monte-Carlo simulation ..........................................................................................72 3.4 RESONANCE EXPERIMENTAL SETUP ...............................................................................76 3.4.1 Overview.................................................................................................................76 3.4.2 Fast-ion Signal Detection........................................................................................78 3.4.3 SAWs Launched by Loop Antenna............................................................................84 3.4.4 SAW Perpendicular Pattern.....................................................................................88 3.5 RESONANCE EXPERIMENT RESULTS ...............................................................................89 3.5.1 Fast-ion Signal Shows SAW-Induced Transport .......................................................89 3.5.2 Measured Doppler Resonance Spectra ....................................................................93 3.5.3 Energy Test of Fast Ion Doppler Resonance...........................................................100 CHAPTER 4 SPECTRAL GAP OF SHEAR ALFVÉN WAVES IN A PERIODIC ARRAY iv OF MAGNETIC MIRRORS ................................................................................................ 104 4.1 MOTIVATION ................................................................................................................105 4.2 SPECTRAL GAP ANALYTICAL THEORY ..........................................................................107 4.3 SAW SPECTRAL GAP EXPERIMENTAL SETUP ................................................................110 4.3.1 Mirror Array in the LAPD.....................................................................................110 4.3.2 Launching SAWs in the Magnetic Mirror Array.....................................................115 4.4 SAW SPECTRAL GAP EXPERIMENTAL RESULTS ............................................................117 4.4.1 Characteristics of Wave Spectra ............................................................................117 4.4.2 Dependence of SAW Spectra on the Number of Mirror Cells..................................118 4.4.3 Characteristics of Spectral Gap and Continua.......................................................119 4.4.4 Varying Mirror Depth (M).....................................................................................122 4.4.5 Verification: Interference Causes Spectral Gap......................................................126 4.4.6 Continuum Quality Factor Varying with Density....................................................129 4.5 SAW SPECTRAL GAP SIMULATION ...............................................................................131 4.5.1 Electro-Magnetic Wave Solver...............................................................................131 4.5.2 Periodic Array of Mirrors......................................................................................132 4.5.3 Simulation of Mirror Array in the LAPD................................................................135 CHAPTER 5 CONCLUSIONS............................................................................................. 143 5.1 SUMMARY ...................................................................................................................143 5.2 IMPLICATIONS ..............................................................................................................145 5.3 FUTURE WORK .............................................................................................................146 APPENDIX A: Typical Ion Beam and the LAPD Plasma Parameters............................. 151 APPENDIX B: Important Data Sets Supporting Experimental Results.......................... 153 APPENDIX C: Schematics for Experimental Apparatuses.............................................. 157 APPENDIX D: Instrument Calibration Data ................................................................... 164 v LIST OF FIGURES FIGURES ………………………………………………………………………………….Page FIG. 1.1. ILLUSTRATIONS OF WAVE-PARTICLE INTERACTIONS IN FUSION DEVICES AND SPACE PLASMAS. ...................................................................................................2 FIG. 2.1. A PHOTOGRAPH OF THE LAPD MACHINE AND THE EXPERIMENTER...........14 FIG. 2.2 DIAGRAM OF THE UPGRADED LARGE PLASMA DEVICE (THE LAPD) WITH PORT NUMBERS LABELED. PORT 7, 13, 35, 41 AND 47 ARE CURRENTLY INSTALLED WITH A TOP RECTANGULAR PORT LARGE ENOUGH FOR FAST-ION SOURCES AND SAW ANTENNAS INSTALLATION. PORT 35 HAS A SIDE-ACCESS RECTANGULAR PORT IN ADDITION........................................................................... 15 FIG. 2.3. ELECTRON-POSITRON CHAMBER OF UC IRVINE .............................................19 FIG. 2.4. SCHEMATICS AND PHOTOGRAPHS OF LITHIUM ION SOURCES FROM HEAT WAVE INC........................................................................................................................23 FIG. 2.5. CROSS SECTIONAL VIEW OF A GENERIC LITHIUM ION SOURCE IN THE LAPD PLASMA AT A PITCH ANGLE OF 30˚. ................................................................25 FIG. 2.6. BEAM DIAGNOSTICS INSTALLED IN THE ELECTRON-POSITRON CHAMBER. ..........................................................................................................................................27