Cosmic-Ray Viscosity
Abstract
The transport equation for cosmic rays scattered by magnetic field irregularities carried in a rarefied conducting fluid has been reexamined. To lowest order in the ratio, U/w, of flow speed to random particle speed, the analysis gives the standard equation first derived by Parker (1965), but additional terms are found in the next order of this ratio. One new term, which reflects viscous damping of fluid motions by the energetic-particle gas, describes both a change in the mean particle momentum and a spreading around the mean. Other new terms, which derive from accelerations of the fluid, describe inertial drift and energy changes. Although these effects are small, they are potentially important at shocks, because they are proportional to the square of velocity derivatives. In addition, they can be significant for the case of pure velocity shear, in which the adiabatic energy change is zero.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1988
- DOI:
- Bibcode:
- 1988ApJ...331L..91E
- Keywords:
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- Boltzmann Transport Equation;
- Cosmic Rays;
- Nonuniform Magnetic Fields;
- Radiation Transport;
- Relativistic Plasmas;
- Viscosity;
- Conducting Fluids;
- Monte Carlo Method;
- Shock Waves;
- Space Radiation;
- COSMIC RAYS: GENERAL;
- HYDROMAGNETICS;
- MAGNETIC FIELDS;
- SHOCK WAVES