COSMIC PLASMAS Physics 418

Prof. Mark Birkinshaw Drs. Martin Hardcastle, Chris Lashmore-Davies, Chippy Thyagaraja, Per Helander

Schedule

18 lectures, Weeks 1-6: Tu1210,Th1000,Fr1000; Room 3.21 and Frank Theatre.

3 problems classes; Mo1400 week 2, Th1100 week 4, Mo1400 week 7 (Room 3.21)

Office hours; Fridays 0900-1100, Physics 3.15.

Pre-requisites

This is a unit of the Physics with Astrophysics degree, and background knowledge of astrophysics at the level of Astronomy 1 (PHYS10500) will be assumed. However, most of the astrophyics material will be accessible with minimal background reading. This element is a pre-requisite for unit PHYS42000 (Current topics in astrophysics and particle physics).

Aims

To provide a foundation for advanced study in plasma physics and astrophysics by describing the specifically plasma-based processes that are the basis for many important phenomena and by providing exercises in working with the equations that describe fast, hot, plasmas. To develop a good physical understanding of plasmas in the Universe, to learn how to calculate the ways that plasmas change under the influences of gravity, magnetic fields, and collisions, and to describe the radiation that these plasmas produce and by which they are detected.

Syllabus

Lecture 1 (Chippy Thyagaraja)
Definition of a plasma; distinction from neutral gas. Debye length, plasma parameter; concept of shielding and quasi neutrality. Two types of description: particle vs continuum. Self consistent field concept. Continuum equations for a neutral (ideal) gas. Continuum equations of motion for a single-fluid plasma.

Lecture 2 (Chippy Thyagaraja)
Particle motions, orbit equations. Simple exact solutions in electromagnetic fields with known symmetries. Drifts and Larmor gyrations in homogeneous and inhomogeneous fields. Adiabatic and exact invariants. Trapping of particles. Examples.

Lecture 3 (Chippy Thyagaraja)
Applications of conservation equations in the fluid description; potential flow/Bernoulli equation. Sound waves (neutral fluids). Vorticity concept and Kelvin's circulation theorem.

Lecture 4 (Martin Hardcastle)
Intergalactic and intracluster medium; heavy elements, origin. X-ray emission; thermal bremsstrahlung and line radiation. Hydrostatic equilibrium; mass estimation. Cooling flows.

Lecture 5 (Martin Hardcastle)
Shocks; Rankine-Hugoniot relations. Particle acceleration in shocks, cosmic rays.

Lecture 6 (Martin Hardcastle)
Supernova remnants; properties, expansion rates, dynamics. Gamma-ray bursters; relativistic shocks.

Lecture 7 (Martin Hardcastle)
Radio galaxies; structures, jets and energy transport. Synchrotron radiation; electron spectrum; electron energy loss. Minimum energy.

Lecture 8 (Per Helander)
Ideal MHD as the simplest, quasi-neutral, continuum description of a single-fluid, single temperature plasma. Equations of motion and ``freezing in'' of fields. MHD waves and simple properties.

Lecture 9 (Per Helander)
Ideal MHD equilibria; limits of validity of MHD: resistive corrections, Ohm's law. Dynamo action.

Lecture 10 (Per Helander)
Elementary stability theory: ``current driven'' (kink) and ``pressure-driven interchange'' instabilities with examples. Free energy and elements of resistive instabilities/reconnection/change of topology.

Lecture 11 (Mark Birkinshaw)
The solar wind (non-magnetic theory); deficiencies in model.

Lecture 12 (Mark Birkinshaw)
The Earth's magnetosphere; radiation belts; aurorae. Other planetary magnetospheres.

Lecture 13 (Chippy Thyagaraja)
Basic concepts of two fluid theory (``extended MHD''); collisions and classical transport from collisions. Elements of the electrostatic drift wave instability of a non-uniform plasma. Essential ideas of fluid and plasma turbulence. Nonlinearity and its effects. Qualitative account of the genesis and consequences of low frequency plasma turbulence.

Lecture 14 (Chris Lashmore-Davis)
Langmuir waves, sound waves and electromagnetic waves in a plasma without an equilibrium magnetic field ; waves in the presence of an equilibrium magnetic field, whistler waves, Faraday rotation.

Lecture 15 (Mark Birkinshaw)
Accretion; Bondi-Hoyle flow. Accretion in star formation; flux freezing; ambipolar diffusion.

Lecture 16 (Mark Birkinshaw)
Accretion disks; viscous effects; angular momentum transport. Algol. X-ray binaries; black holes, neutron stars, white dwarf stars.

Lecture 17 (Chris Lashmore-Davis)
Kinetic description of a plasma, wave-particle interaction, Landau damping.

Lecture 18 (Chris Lashmore-Davis)
Nonlinear wave interactions, coupling of longitudinal and transverse waves. Raman and Brillouin scattering.

Problems class 1 (Chippy Thyagaraja)
Computational exercises in plasma physics.

Problems class 2 (Martin Hardcastle)
Cluster atmospheres; shocks; supernovae; radiation from fast particles.

Problems class 2 (Mark Birkinshaw)
Stable and unstable flows; winds; accretion flows; particles in near-Earth environment.

Students with difficulties working through the problems, or wanting to discuss the material presented in lectures, are invited to visit Prof. Birkinshaw during his office hours.

Books for the course

The physics of fluids and plasmas: an introduction for astrophysicists, Choudhuri, A.R., 1998. Cambridge University Press; ISBN 0-521-55543-4. Probably the most suitable text for the course as a whole.

Physical processes in the interstellar medium, Spitzer, L., 1978; John Wiley & Sons Inc.; ISBN 0-471-02232-2. An important reference for gas-dynamical processes in the Galaxy.

Astrophysics of gaseous nebulae and active galactic nuclei, Osterbrock, D.E., 1988. University Science Books; ISBN 0-935-70222-9. An important reference for radiation from astrophysical plasmas.

Introduction to plasma physics and controlled fusion: volume 1, plasma physics, Chen, F.F., 1990 (second edition). Plenum; ISBN 0-306-41332-9. A highly-praised introduction to the subject, including many descriptions of related experiments.

Introduction to plasma physics, Goldston, R.J., Rutherford, P.H., 1995. Institute of Physics; ISBN 0-750-30183-X. An excellent recent addition to the plasma physics literature.