Attenuation of longitudinal electro-acoustic waves in a plasma
There are several practical situations in partially ionized plasmas when both collisionless (Landau) damping and electron-neutral collisions contribute to the attenuation of longitudinal waves. The longitudinal-wave dispersion relation is derived from Maxwell's equations and the linearized Boltzmann equation, in which electron-- neutral collisions are represented by a Bhatnagar-Gross-- Krook model that conserves particles locally. The dispersion relation predicts that, for a given signal frequency w, an infinite number of complex wavenumbers k/sub n/ can exist. Using Fourier- Laplace transform techniques, an integral representation for the electric field of the longitudinal waves was readily derived. Then, using theorems from complex variable theory, a modal expansion of the electric field could be made in terms of an infinite sum of confluent hypergeometric functions, whose arguments were proportional to the complex wavenumbers k/sub n/. It was demonstrated numerically that the spatial integral of the square of the electric field amplitude decreased as the electron-neutral collision frequency increased. Also, the amount of energy contained in the first few (lowest) modes, and the coupling between the modes, was examined as a function of plasma frequency, signal frequency, and collision frequency. (auth)
- Research Organization:
- Air Force Cambridge Research Labs., L. G. Hanscom Field, MA
- NSA Number:
- NSA-29-025852
- OSTI ID:
- 4351671
- Journal Information:
- J. Plasma Phys., v. 11, pp. 37-49, Journal Name: J. Plasma Phys., v. 11, pp. 37-49; ISSN JPLPB
- Country of Publication:
- United Kingdom
- Language:
- English
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