Application of torch plasma, which is intended as an ignition aid within a scramjet engine, is studied. The plasma jet generated by a torch module is described by detailing the voltage-current characteristics and through imaging of its plume in a quiescent environment and in a supersonic crossflow. This torch system, with its high voltage discharge, can be operated in periodic (60-Hz) or pulsed modes, depending on the power supply used. In the 60-Hz mode, the capacitors are charged at the line frequency of 60 Hz, resulting in a cyclical discharge. In this mode, the cycle energy is up to 25 J. However, this energy is mainly limited by the power handling capability of the power supply. In the pulsed mode, the torch can deliver up to 100 J in each pulse. Within the Mach-2.5 supersonic flow, which approximates the scramjet-engine startup condition, the penetration height and the volume of torch plume into the crossflow vs. gas supply pressure and plasma energy are determined.