Analysis of the efficiency of MHD cycle supported by ns pulsed discharge pre-ionization*

Numerical characterization of nanosecond pulsed discharges has been conducted in a strong magnetic field environment. Streamer discharge development and plasma generation in pure CO₂ was analyzed when magnetic field was directed along the axis of the discharge cell. Numerical simulations were based of a two-dimensional fluid model. It is shown that strong magnetic field affect dramatically on the plasma formation. We simulate the NS-DBD plasma conductivity in a wide range of the external magnetic field amplitudes. Comparison with the experimental results shows an excellent agreement between calculated and measured plasma distribution. The energy spent on ionization of the gap and Joule heating of the gas is Q_ion ~ 0.3 mJ during 6 ns of the discharge for MHD generator volume of 50×50×100 mm³. The total energy extracted from the "hot" flow at U = 1571 m/s during 10 ms after the pre-ionizing pulse is 28.3 J/m³, which gives Q_MHD = 7.1 mJ from the same volume. Thus, in an ideal Faraday MHD generator with segmented electrodes, the energy extracted by MHD generator in a high-speed flow could be much higher than the energy required for gas ionization: Q_MHD/Q_ion ~ 24.