A new relativistic collision rate calculation
The collision rates that are used in RELFLAP, the relativistic fluid code for high-power microwave propagation through the atmosphere, are obtained from the first three moments of the relativistic Boltzmann collision integral. Expressions for the particle, momentum, and energy transfer rates caused by elastic, inelastic, and ionizing collisions were previously obtained by evaluating the moments of the relativistic Boltzmann collision integrals using a relativistic momentum distribution function and assuming scattering cross sections that are independent of the scattering angle. The resulting integral expressions are evaluated numerically over a two-dimensional grid of mean kinetic and thermal velocity in the code RELFCOL. The purpose of this memorandum is to document the calculation of new relativistic collision rates using angular dependent scattering cross sections. This new calculation is based on a similar nonrelativistic treatment given by Roussel-Dupre and on the earlier relativistic rate calculation. The earlier calculation was based on the incorrect assumption that the collision rates were proportional to the normalized mean electron momentum. This assumption yields unnaturally large collision rates for the extreme relativistic case. In fact, the rates for collisions between electrons and stationary neutral particles are proportional to the mean electron velocity. The new rate calculation is based on this fact. New derivations of the Boltzmann collision integrals, similar to the original derivations, are presented. Relativistic scattering cross sections are discussed. Expressions for the particle, momentum, and energy transfer rates were derived using differential scattering cross sections. Some of the computational methods used to calculate the collision rate and the results of the rate calculation are discussed.
- Research Organization:
- EG and G Energy Measurements, Inc., Los Alamos, NM (United States). Los Alamos Operations
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC08-88NV10617
- OSTI ID:
- 10103286
- Report Number(s):
- EGG--10617-5093; LAO--2732-2172; ON: DE92003690
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
664300
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
BOLTZMANN EQUATION
CLASSICAL AND QUANTUM MECHANICS
COLLISION PHENOMENA
CROSS SECTIONS
EARTH ATMOSPHERE
ELASTIC SCATTERING
ELECTRON-MOLECULE COLLISIONS
INELASTIC SCATTERING
IONIZATION
LINEAR MOMENTUM
MICROWAVE RADIATION
NUMERICAL SOLUTION
R CODES
RELATIVISTIC RANGE
SCATTERING
WAVE PROPAGATION