Characteristic study of a portable arc microwave plasma torch

The development of a plasma torch, which carries desirable features to be an ignition aide within a supersonic combustor, is studied. The desirable features include: 1) a microwave adaptor arrangement to couple additional power (from microwave as well as arc discharge) to the plasma torch; 2) an additional port for fuel injection; and 3) compactness (including the power supply), portability, and light weight. The plasma jet generated by this torch is described by the cycle energy of the discharge and by the imaging of its plume under various conditions, supply air pressures, and microwave (on or off) to the torch. This torch system, with its high-voltage discharge, is operated in periodic (60-Hz) mode. The capacitors in the circuit of the power supply are charged at a line frequency of 60 Hz, resulting in a cyclical discharge. The cycle energy reaches up to 12 J. The microwave electric field has a profound effect on the arc discharge. It intensifies the emission and increases the volume of the arc loop region. It also enhances the electron temperature significantly, as shown by the emission spectroscopy of the torch. The spatial distribution of the microwave electric field outside the nozzle of the torch module is not affected by the supersonic crossflow, which is a favorable feature for increasing the penetration depth of the torch plume into the supersonic crossflow in the combustor.