Amplification of acoustic waves in weakly ionized plasma

The amplification factor characterizing the amplification of acoustic distu rbances in gas-discharge plasma is calculated with allowance for the nonuni form heating of neutral gas due to elastic collisions with the hot electron gas. It is shown that the heat release in the neutral plasma component due to elastic collisions between electrons and neutral particles is insuffici ent to provide the amplification factor of the order of measured values. It is also shown that the heat release due to superelastic collisions between excited atoms and atoms in the ground state can far exceed the heat releas e due to elastic collisions between electrons and neutral particles. A new mechanism of amplification of acoustic disturbances in plasma is proposed. This mechanism is associated with the superelastic relaxation of the nonequ ilibrium energy store accumulated in the atomic electron levels perturbed d ue to electron-atom inelastic collisions. It is shown that when the heat re lease is sufficiently high, one should assume that there exists a heat remo val mechanism more efficient than heat conduction, this mechanism preventin g intense gas heating, thereby providing acoustic wave amplification in pla sma.