PHYS 780. Basic Plasma Physics

Transcription

1 Phys780: Plasma Physics Lecture 1: Basic concepts 1 PHYS 780. Basic Plasma Physics Time: 1:00 pm -2:25 pm, U.S. Eastern Time, Monday, Wednesday Location: GITC 1403, on-line via VYDEO (Students will receive a URL to log into for the session) Instructor: Alexander Kosovichev sasha@bbso.njit.edu Grades: biweekly assessments + presentations Course materials:

2 Phys780: Plasma Physics Lecture 1: Basic concepts 2 Lecture Plan 1. September 3, Wednesday, Introduction. Basic concepts. 2. September 8, Monday, Basic properties of plasma. Quasineutrality. Debye shielding. 3. September 10, Wednesday, Plasma ionization. Saha equation. 4. September 15, Monday, Elementary processes in plasma. 5. September 17, Wednesday, Coulomb collisions. 6. September 22, Monday, Particle motion in magnetic field. 7. September 24, Wednesday, Magnetic mirrors. Radiation belts. 8. September 29, Monday, Kinetic theory of plasma. Vlasov equation. 9. October 1, Wednesday, Two-stream instability. Ion-acoustic waves. 10. October 6, Monday, Collisions. Fokker-Planck Equation. 11. October 8, Wednesday, Plasma resistivity. Runaway breakdown and electric discharges. 12. October 13, Monday, MHD approximation. 13. October 15, Wednesday, Generalized Ohm s law.

3 Phys780: Plasma Physics Lecture 1: Basic concepts October 20, Monday, Energy and momentum transport. Chapman-Enskog theory. 15. October 22, Wednesday, Heat transport. Saturation of heat flux. 16. October 27, Monday, Plasma transport in magnetic field. Ambipolar diffusion. 17. October 29, Wednesday, Propagation of electromagnetic waves in plasma. 18. November 3, Monday, Plasma waves. Landau damping. 19. November 5, Wednesday, Plasma radiation: bremsstrahlung, recombination, synchrotron. 20. November 10, Monday, Alfven waves. 21. November 12, Wednesday, Frozen magnetic flux. Magneto-acoustic waves 22. November 17, Monday, Dynamo theory. Helicity. 23. November 19, Wednesday, Quasi-linear theory of Landau damping. Particle acceleration. 24. November 24, Monday, Resistive instabilities. Magnetic reconnection. 25. December 1, Monday, Plasma Applications. Presentations. 26. December 3, Wednesday, Non-linear effects in plasma. Collisionless shocks.

4 Phys780: Plasma Physics Lecture 1: Basic concepts December 8, Monday, MHD equilibrium and stability. Force-free field. 28. December 10, Wednesday, Thermonuclear fusion. Tokamak. Plasma experiments.

5 Phys780: Plasma Physics Lecture 1: Basic concepts 5 Books 1. T.J.M. Boyd and J.J. Sanderson, The Physics of Plasmas, Cambridge Univ.Press, J.A. Bittencourt, Fundamentals of Plasma Physics, 3rd edition, Springer, P.A. Sturrock, Plasma Physics, Cambridge Univ. Press, R.J. Goldston, P.H. Rutherford, Introduction to Plasma Physics, IOP Publ., F. L. Waelbroeck, R. D. Hazeltine, The Framework of Plasma Physics (Frontiers in Physics, V. 100), R.Dendy (Ed.) Plasma Physics: an Introductory Course, Cambridge Univ. Press, R.O. Dandy, Plasma Dynamics, Oxford Sci. Publ., R. Fitzpatrick, Introduction to Plasma Physics, 1998, 9. R.D. Hazeltine, F.L. Waelbroeck, The Framework of Plasma Physics, Perseus Books, L. Spitzer, Jr. Physics of Fully Ionized Gazes, Interscience Publishers, Ya.B. Zel dovich and Yu.P. Raiser, Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena, Dover, 2002

6 Phys780: Plasma Physics Lecture 1: Basic concepts NRL Plasma Formulary (handbook)

7 Phys780: Plasma Physics Lecture 1: Basic concepts 7 Presentation Topics 1. Computer simulation of cold plasma oscillations (Birdsall and Langdon, Plasma Physics via Computer Simulations, p.90) 2. Two-stream instability (ibid, p.104) 3. Landau damping (ibid. p.124) 4. Particle motion in electric and magnetic fields (tokamak) /plasma1/matlab spm.html 5. Jets from magnetized accretion disks 6. Plasma accelerators 7. Liquid ionization detectors 8. Magnetic reconnection in solar flares 9. Magnetic helicity 10. Tokamak experiments (Dendy, R. Plasma Physics, chap.8) 11. Magnetospheres of planets (ibid. chap.9-i) 12. Collisionless shocks (ibid. chap.9-ii) 13. Laser-produced plasmas (ibid. chap. 12)

8 Phys780: Plasma Physics Lecture 1: Basic concepts Industrial plasmas (ibid. chap. 13) 15. Dynamo experiments (Dynamo and Dynamics, ed P.Chossat et al, 2001) 16. Origin of cosmic rays (Longair, M., 1997, High-Energy astrophysics, Vol.2)

9 Phys780: Plasma Physics Lecture 1: Basic concepts 9 1. Introduction. Basic concepts. ([1] p.1-11; [2] p. 1-28; [8] p.2-13) Definition of plasma Plasma is quasi-neutral ionized gas. It consists of electrons, ions and neutral atoms. Brief history of plasma A transparent liquid that remains when blood is cleared of various corpuscules was named plasma (after the Greek word πλασµα, which means moldable substance or jelly ) by Johannes Purkinje, the great Czech medical scientist. Irving Langmuir, Nobel prize-winner, first used plasma to describe an ionized gas. He studied tungsten-filament light

10 Phys780: Plasma Physics Lecture 1: Basic concepts 10 bulbs to extend their lifetime, and developed a theory of plasma sheaths, the boundary layers between the plasma and solid surface. He also discovered periodic variations of electron density - Langmuir waves. Major areas of plasma research 1. Radio broadcasting and Earth s ionosphere, a layer of partially ionized gas in the upper atmosphere which reflects radiowaves. To understand and correct deficiencies in radio communication E.V. Appleton (Nobel price 1947) developed the theory of electromagnetic waves propagation through a non-uniform, magnetized plasma. 2. Astrophysics, 95-99% of the visible Universe consists of plasma. Hannes Alfvén around 1940 developed the theory of magnetohydrodynamics, or MHD, in which plasma is treated as a conducting fluid (Nobel price in 1970). Two topics of MHD

11 Phys780: Plasma Physics Lecture 1: Basic concepts 11 are of particular interest: magnetic reconnection (change of magnetic topology accompanied by rapid conversion of magnetic energy into heat and accelerated particles) and dynamo theory (generation of magnetic field by fluid motions). 3. Controlled nuclear fusion, creation of hydrogen bomb in This research was mostly about hot plasma confinement and instabilities in magnetic field. Reaction: d+t α+n+17.6mev required T = 10 8 K and density n = m Space plasma physics. James Van Allen discovered in 1958 the radiation belts surrounding the Earth, using data transmitted by the Explorer satellite. This led to discovery and exploration of the Earth s magnetosphere, plasma trapping in magnetic field, wave propagation, and magnetic reconnection, the origin of geomagnetic storms.

12 Phys780: Plasma Physics Lecture 1: Basic concepts Laser plasma physics. Laser plasma is created when a high powered laser beam strikes a solid target. Major application of laser plasma physics are inertial confined fusion (focus beams on a small solid target) and plasma acceleration (particle acceleration by strong electric field in laser beam. Plasma can consist not only of electron and ions. Electron-positron plasma exists in pulsar atmospheres. In semiconductors, plasma consists of electron and holes.

13 Phys780: Plasma Physics Lecture 1: Basic concepts 13 The unit systems in plasma physics SI units [m]=kg; [x]=m; [t]=s; [F]=kgm/s 2 =N (Newton); [E]=Nm=J (Joule); [T]=K (Kelvin); E = kt, where k = J/K; [I]=A (Ampere) ; [q]=a s=c (Coulomb) ; [U]=J/C=V (Volt) ; [ E]=V/m; [ B]=V s/m 2 =T (Tesla). In plasma physics, the energy and temperature are often given in units of ev: the electron charge is: C, then 1 ev= C V= J. For temperature: T[eV] k B T[K] 1eV = J J/K = 11600K

14 Phys780: Plasma Physics Lecture 1: Basic concepts 14 CGS units [m]=g; [x]=cm; [t]=s; [F]=g cm s 2 =dyn (from Greek dyne); [E]=g cm 2 s 2 =erg (from Greek ergon); [q]=esu=(10/c) C e = esu (electrostatic unit) (where c = cm/s) [ B] = G (Gauss) = 10 4 T; In CGS, magnetic and electric fields have the same dimension.

15 Phys780: Plasma Physics Lecture 1: Basic concepts 15 Fundamental Constants SI units CGS units Speed of light c = m s cm s 1 Gravity const. G = N m 2 kg cm 3 g 1 s 2 Planck s const. h = J s erg s Boltzmann const. k = J K erg K 1 Proton mass mp = kg g Electron mass me = kg g Electron charge e = C esu Astrophysical Constants SI units CGS units Mass of Earth M E = kg M E = g Radius of Earth R E = m R E = cm Mass of Sun M S = kg M S = g Radius of Sun R S = m R S = cm Luminosity of Sun L S = W L S = erg s 1 Hubble s constant H 0 = 3.24 h s 1 H 0 = 3.24 h s 1 CMB Temperature T 0 = 2.73 K T 0 = 2.73 K

16 Phys780: Plasma Physics Lecture 1: Basic concepts 16 Conversions SI units CGS units 1 ev 1 ev = J 1 ev = erg 1 Jy 1 Jy = W m 2 Hz 1 Light year lt-yr = m lt-yr = cm Parsec 1pc = m 1pc = cm

17 Phys780: Plasma Physics Lecture 1: Basic concepts 17 Classical Equations of Electricity and Magnetism in SI and CGS Units International System (SI) C.G.S. (Gauss) system B = 0 B = 0 B t + E = 0 1 c B t + E = 0 E = ρ ǫ 0 E = 4πρ B 1 E c 2 t = µ 0J B 1 c E t = 4π c J F = e( E + v B) F = e( E + 1 c v B)

18 Phys780: Plasma Physics Lecture 1: Basic concepts 18 where B is the magnetic field strength, E is the electric field strength, ρ is the electric charge density, J is the electric current density, v is the plasma velocity, c is the speed of light, e is the electron charge, ǫ 0 is the electric constant (the vacuum permittivity), µ 0 is the magnetic constant (the vacuum permeability).

19 Phys780: Plasma Physics Lecture 1: Basic concepts 19 If a formula is known in SI, the corresponding formula can be found in CGS by the use of the following rules: SI CGS ǫ 0 1/4π µ 0 4π/c 2 q q B E B/c E Examples of the unit conversion: the speed of light 1/ µ 0 ǫ 0 1/ 4π/c 2 1/4π = c Coulomb force qq 4πǫ 0 r 2 qq r 2

20 Phys780: Plasma Physics Lecture 1: Basic concepts 20 Larmour force q( E + v B) q( E + v B/c) Note that these rules do not give the conversion of units. The SI units are more practical for plasma experiments, but the CGS units are better for physical understanding. In this course, I use the CGS units.

21 Phys780: Plasma Physics Lecture 1: Basic concepts 21 Problem 1. The GOES satellite measures the solar X-ray output in the 1-8 Angstrom ( nm) and Angstrom ( nm) passbands: Estimate the temperature (in ev and K) of the solar plasma emitting in these passbands.