Evaluation of the Driver Chamber Efficiency for an Arc Driven Shock Tube

A prestressed ceramic driver chamber, which is capable of withstanding 30 000 psi internal pressure, has been designed, built and operated. Energy input to the chamber was determined by the voltage on the capacitor bank used to arc heat the gas. Temperature in the head was derived from the velocity of expansion into a vacuum. The results indicated an 0.49 efficiency for transfer of energy from the capacitor bank to the gas. This was confirmed within the experimental accuracy of 10% by pressure measurements with a piezoelectric probe mounted in the driver chamber. Driver chamber temperatures up to 28 000°K were observed. No significant radiation or ablation effects were noted. Energy transfer is achieved in 35 msec after which equilibrium conditions are observed until the diaphragm opens at 70 msec. Driver pressures of up to 18 000 psi were recorded.