APPROXIMATE FORMULAS FOR ION AND ELECTRON-TRANSPORT COEFFICIENTS IN CROSSED ELECTRIC AND MAGNETIC-FIELDS

Momentum-transfer theory is used to derive approximate expressions for transport properties of electrons and ions in a gas in crossed electr ic and magnetic fields. Included in the formal discussion are the gene ralised Einstein relations, negative differential conductivity, Tonks' theorem and the equivalent reduced electric field concept. Specific t opics dealt with include the ratio D(parallel-to)/D(perpendicular-to) for electrons, which 'flips over' as the magnetic field is increased, the enhancement of negative differential conductivity through increase d B/N, and a discussion of anisotropic scattering.