## Abstract

The diffusion tensor in an isolated electron or light ion swarm subject only to elastic collisions with molecules has been formulated from the multiterm expansion of the Boltzmann equation in the hydrodynamic description. Derived diffusion coefficients for the transverse and longitudinal directions include the additional terms representative of the curvature effect under the action of an electric field besides the usual two-term expressions. Discussion is, particularly, focused on the relation between the transverse diffusion coefficient D_{T} and its conventional expression D_{V}. Numerical calculations have been made for the electron swarm in a model gas having a momentum transfer cross-section, Q_{m}( epsilon )=Q_{0} epsilon ^{beta} ( beta =0, ^{1}/_{2}, 1), with isotropic scattering. It will be recognised that an appreciable degree of discrepancy occurs between D_{T} and D_{V} with the increase of the power beta , i.e. of the cross-sectional dependence on energy.

Original language | English |
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Article number | 009 |

Pages (from-to) | 699-708 |

Number of pages | 10 |

Journal | Journal of Physics D: Applied Physics |

Volume | 17 |

Issue number | 4 |

DOIs | |

Publication status | Published - 1984 Dec 1 |

## ASJC Scopus subject areas

- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films