Influence of supersonic ion clusters on the plasma neutral component

3. Conclusions

[21] Summarizing the results of the experimental [Klimov et al., 1982; Mishin et al., 1991] and theoretical studies [Pavlov, 1996, 2002b], one can conclude that the field distribution in the problem on the motion of a strong shock wave in weakly ionized plasma is characterized by several dimensionless parameters. The most significant of them are the Mach number M 1, the ion-sonic Mach number 2>M_i >1, the ionization degree ( d 1 ), and the ratio of the temperatures of electrons and neutral particles B equiv T_e/T_i 1. The ion-sonic Mach number is related to the Mach number by the formula M_i = M(g/B)^1/2, where g is the ratio between the specific heat capacities of the neutral gas. Because of strong nonlinearity and a dispersion, there appears a significantly nonmonotonic dependence of the field amplitude on the velocity of the shock wave when the condition M_i approx 1.6 div 2 is fulfilled. In the resonant regions, the propagation of the shock wave in the weakly ionized plasma is determined by the ion-sonic Mach number. Under the condition M = const, but at different values of the B parameter, the flowing around of the body will be different. The obligatory condition for the resonance occurrence is the requirement M_i approx 1.6 div 2. This is a peculiarity of the "plasma effect".

[22] It should be noted that a correct modeling of plasma experiments in laboratory conditions present a complicated problem because of the contamination of the working gas by the products of electrode erosion and also presence of solid particles in the gas flowing out of the nozzle. The latter may be ice crystals, pieces of films of oxides from the incoming tubes, and dust from the air. Such contaminations are badly controlled especially in the experiments in aerodynamic tubes. In a plasma-dynamic experiment, a formation in the flow of qualitatively new medium (dust plasma containing microscopic charged particles) is possible. In such plasma, appearance of a complex of even more complicated nonlinear resonance effects determined by many parameters is possible [Pavlov, 2002b].