Theory of the polarization bremsstrahlung from thermal electrons scatteredby the Debye sphere of an ion in a plasma

The polarization bremsstrahlung from thermal electrons scattered by the Deb ye sphere of an ion in a plasma is studied in the quasiclassical approximat ion. The model of the local plasma frequency is used to check the validity of the asymptotic expression for the polarizability of the electron cloud o f an ion in the high-frequency range. This asymptotic expression is then us ed to derive a formula for the intensity of the total effective polarizatio n bremsstrahlung. The R factor (the ratio of the contribution from the pola rization bremsstrahlung to the contribution from conventional static bremss trahlung) is obtained as a function of the plasma coupling parameter and el ectron density in order to analyze the role of the polarization bremsstrahl ung in the total bremsstrahlung of the thermal plasma electrons. The spectr al intensity of the effective polarization bremsstrahlung is calculated in the rotational approximation, which was previously employed in the theory o f conventional static bremsstrahlung. It is shown that the spectral intensi ty of the polarization bremsstrahlung from thermal electrons scattered by t he Debye sphere around an ion, as compared with the polarization bremsstrah lung by fast superthermal electrons, decreases more gradually with increasi ng frequency. (C) 2001 MAIK "Nauka/Interperiodica".