Agnar Pytte

Hamiltonian of a slightly relativistic plasma

In the past, treatments of plasma to order v2/c2, where v is the thermal speed of the particles, have relied on a Lagrangian formalism or on coarse graining techniques. It is shown that a Hamiltonian formulation where only particle degrees of freedom are considered is possible and a Hamiltonian to order v2/c2 is obtained. This Hamiltonian is valid within the limits of the random phase approximation.

On Cooled Anodes in Contact with a Laminar Arc-Heated Flow

This paper is concerned with the physics and operating characteristics of cooled anodes In contact with an arc-heated laminar plasma flow in a constant area duct. Various modes of anode behavior are identified and described. Some Influences of gas type, flow rate, arc current, anode material and geometry are demonstrated. A theory is developed to explain the low-current mode of the anode characteristic. It is shown that the local current density on the anode surface is related approximately to the surfaces local bias relative to its electrically floating voltage. Anode current distribution data is presented; the distribution is shown to be unstable above a transition bias volt,. age, with the current concentrating intensely on the edge of the anode toward the cathode. Neighboring points on the duct wall are shown to be electrically independent. This fact greatly simplifies an interpretation of anode phenomena. The information presented makes a fairly complete picture of the physical behavior of finite-length, cooled anodes in contact with fully-developed laminar plasma-arc flows.

Kinetic equation of a slightly relativistic plasma

A fully convergent kinetic equation, with no arbitrary cutoffs, is derived for a homogeneous, isotropic, slightly relativistic plasma. The equations is good to first order in the ratio of the electron thermal energy to the electron rest energy.

High‐frequency conductivity of a magnetoplasma

The conductivity is calculated with a convergent method requiring no cutoffs. The close collisions are treated quantum mechanically.

Conductivity of a Magnetoplasma from a Quantum Mechanical Convergent Kinetic Equation

The quantum‐mechanical version of Baldwins convergent kinetic equation is used to calculate the collisional part of the ac electrical conductivity tensor of a multispecies magnetoplasma to second order in the wave vector. Both dominant (Coulomb logarithm) and subdominant terms are calculated exactly to first order in the plasma parameter. Full account is taken of the heavy ion motion.

Bremsstrahlung in a magnetized plasma

Using Kirchoff’s law, the bremsstrahlung emission coefficient, in the dipole approximation, is calculated for a magnetized plasma. Effects due to dynamic screening, large momentum transfer between particles, and overlapping of particle wavefunctions during close collisions are taken into account.

Conductivity of a Magnetoplasma from a Convergent Kinetic Equation

The convergent classical kinetic equation of Kihara and Aono is used to calculate the collisional part of the ac electrical conductivity of a magnetoplasma to second order in the wave vector. Both dominant (Coulomb logarithm) and subdominant terms are evaluated exactly to first order in the plasma parameter.

Magnetic Field Corrections to the Plasma Bremsstrahlung Spectrum

The bremsstrahlung emitted in a Maxwellian plasma in a constant magnetic field is calculated. It is assumed that the wave frequency ω is large compared with the plasma frequency ωp and the electron cyclotron frequency Ωe.

A Note on Perturbation Theory in Nearly Periodic Systems

It is shown that for a particle in periodic or nearly periodic motion, an integrated form of the equations of motion may be the better starting point for an approximate calculation of the orbit. The motion of a charged particle in a static, inhomogeneous magnetic field is used to illustrate how this approach avoids the difficulty of the spurious secular terms to all orders of the approximation.

Effect of Ion Motion on the Collisional Conductivity of a Magnetoplasma

The collisional contribution to the electrical conductivity is obtained for a magnetoplasma consisting of an arbitrary mixture of charged particle species. The calculation is based on the Landau collision term and is carried out to second order in the wavenumber. Full account is taken of the ion motion.