Bernstein modes in a weakly relativistic electron-positron plasma

The kinetic theory of weakly relativistic electron-positron plasmas, producing dispersion relations for the electrostatic Bernstein modes was addressed. The treatment presented preserves the full momentum dependence of the cyclotron frequency, albeit with a relaxation on the true relativistic form of the distribution function. The implications of this new treatment were confined largely to astrophysical plasmas, where relativistic electronpositron plasmas occur naturally

Thomson Scattering of Coherent Diffraction Radiation by an Electron Bunch

The paper considers the process of Thomson scattering of coherent diffraction radiation (CDR) produced by the preceding bunch of the accelerator on one of the following bunches. It is shown that the yield of scattered hard photons is proportional to N$_e^3$, where N$_e$ is the number of electrons per bunch. A geometry is chosen for the CDR generation and an expression is obtained for the scattered photon spectrum with regard to the geometry used, that depends in an explicit form on the bunch size. A technique is proposed for measuring the bunch length using scattered radiation characteristics.Comment: 14 pages, LATEX, 6 ps.gz figures, submitted to Phys.Rev.

Inductive effects in flux conserving tokamaks

Scenarios are worked out in straight circular cylindrical geometry for the evolution of flux conserving sequences of equilibria as the plasma is heated or compressed. It is shown that force-free currents are induced when the low pressure region at the edge of the plasma is compressed against a flux conserving wall. A force-free surface current is induced if there is a vacuum region between the expanding plasma and the wall. These edge currents run opposite to the direction of the current in the main body of the plasma. The force-free currents can be avoided or reversed at the edge of a plasma with diffuse resistivity profile by programming the total longitudinal current as the plasma is heated or compressed