Abstract:The performance of the hypersonic flight vehicle could be revolutionarily promoted by the application of the MHD technology, which require the conductivity of the supersonic speed airflow as the premise condition, with precedential analysis having indicated that Non-equilibrium ionization mode should be considered into the ionization of the low temperature supersonic speed airflow. The air-breathing Ma3 supersonic wind tunnel was designed in this paper, with space-discharge characteristics of the plasma investigated under static condition and Ma3 airflow. The experimental result indicated that, when the device discharged in supersonic airflow, the breakdown voltage reached about 2.88kV, which is obviously higher than parallel 1.85kV under static condition, and when the peak forward voltage was about 4kV in a supersonic airflow, about15.6mJ of the energy, that is higher than parallel 8.58mJ of energy released under static condition, was released into the flow field in a single pulsed discharge, with the discharge in supersonic airflow relatively steady, more even as the frequency grew, and appearing to be threadlike as the discharged voltage grew. To obtain the spacially homogeneous plasma in supersonic airflow, a relatively low pressure and high-performance nanosecond pulse power supply are both needed.