Introduction To Experimental Plasma Physics: Physics 180e, Plasma Physics Laboratory

Physics l8OE Plasma Physics Laboratory INTRODUCTION TO EXPERIMENTAL PLASMA PHYSICS Volume 1 Alfred Y. Wong Physics Department University of California at Los Angeles Copyright© Spring, 1977 Plasma Physics Laboratory Physics 180 E CONTENTS: Introduction Symbols and Commonly Used Constants Chapter I. Plasma Production 1) The D.C. Discharge 2) Discharge in Magnetic Multipole Machines 3) Experimental Procedure 4) Appendix A: The Vacuum System 5) Appendix 8: Construction of Plasma Sources Chapter II. Basic Plasma Diagnostics 1) Langmuir Probe 2) Double Probe 3) Microwave Interferometer 4) Experimental Procedure 5) Appendix A: Description of Probe and Circuitry Chapter III. Energy Analyzer 1) Energy Analyzer Design 2) Performance of Ion Energy Analyzer 3) Experimental Procedure 4) Appendix A: Ion Beam Characteristics in Double Plasma Device 5) Appendix 8: Analyzer Specifications Chapter IV. Ion Acoustic Waves 1) Introduction 2) Linear Dispersion of Ion Acoustic Wave 3) Damping 4) Ion Acoustic Shocks 5) Description of Experiment 6) Appendix A: Landau Damping of Ion Acoustic Waves 7) Appendix B: Collective and Free-Streaming Contributions to Propagating Ion Acoustic Waves 8) 9) 10) Appendix C: Damping of Ion Acoustic Waves in Presence of a Small Amount of Light Ions Appendix D: Ion Acoustic Shocks Appendix E: Ion Beam-Plasma Interactions in a One Dimensional Plasma Chapter V. Electron Plasma Waves 1) Basic Theory 2) Experimental Configuration 3) Experimental Procedure 4) Appendix A: Equation for High Frequency Electric Field 5) Appendix 8: Wave Detection Acknowledgments In the course of writing this volume, I have drawn upon the experience of many of my former and present colleagues, in particular: Drs. W. Gekelman, W. Quon, K. MacKenzie, E. Ripin, and R. Stenzel. Many graduate students have made many useful suggestions and contributions to the text: W. DiVergilio contributed to the Appendix on ion beam-plasma interaction; K. Jones and D. Eggleston carefully proofread the many chapters and assisted in bringing the volume to its present form; R. Schumacher assisted me in earlier drafts. Symbols and Commonly Used Constants Symbols Cs= ion sound speed ≅ KTe M E = particle kinetic energy Eb = beam energy Ies, Iis = electron, ion saturation current K = Boltzmann's constant M, mi = ionic mass Tb = ion beam temperature equivalent Te, Ti = electron, ion temperature Vd = discharge potential Vg = grid potential Vf = floating potential Vs = plasma space potential ae = electron thermal speed = KTe m ai = ion thermal speed = KTe M e = electronic charge fb(v) = beam ion velocity distribution fe(v), fi(v) = electron, ion velocity distribution functions k = wavenumber m, me= electronic mass n, ni = electron density, ion density nb = beam density Vb = Bohm (Tonks-Langmuir) speed = KTe M vb = beam velocity Ve = average magnitude of electron velocity (3 dim) = 8 KTe m vg = group velocity vp = phase velocity zo = axial plasma position λD, λDe = electron Debyelength = γKTe 4πne 2 θ =ion/electron temperature ratio = Ti Te ω = frequency ωp, ωpe = electron plasma frequency = 4πne 2 m ωpi = ion plasma frequency = 4πne 2 M ω = normalized wave frequency = ω ω pi σc = charge exchange cross sections, e.g. σAr+-Ar ~ 5 x 10 -15 cm2 (velocity dependent) Physical Constants (CGS) Boltzmann's constant K = 1.3807 _ 10-16 erg/° K Elementary charge e = 4.8032 _ 10-10 statcoulomb Electronic mass m = 9.1095 _ 10-28 gram Hydrogen atom mass Mp