In order to restrain the prepulse of a high energy fluence diode, a flash-over switch made of a nylon cylinder was inserted in between the cathode stalk and the cathode. Secondary prepulse technique was developed to lower the flash-over voltage of the switch. It was found that the surface resistivity of the nylon insulator changes considerably after each shot and this resistivity on the order of 107 Ω/m is most suitable for a 20-mm long flash-over switch to operate stably at a lower flash-over voltage.

A commercial mode locked cavity dumped Nd:YAG dye laser operating at 10 Hz repetition rate is modified to produce a high contrast (>5000:1) single laser pulse while maintaining the energy stability and high beam quality. A trigger generator biases the cavity dumping photodiode, which is triggered externally by a pulse from the microprocessor-based control unit controlling a ∼2 J/200 ps laser chain. In the laser chain, the high contrast (>5000:1) is achieved by an external pulse selector based on single Pockel's cell to select a single laser pulse of high contrast, which is a prerequisite for experimental study of the equation of state. Laser-induced shock velocity measurement in thin aluminum, gold on aluminum, and copper on aluminum foil targets using this modified laser system are also presented. The equation of state of Al, Au, and Cu obtained using an impedance matching technique are in agreement with the reported results of SESAME and simulation results.

The present study evaluated the ability of a weak electrical prepulse to modify startle caused by a more intense shock. Painful electrical shocks (150 V, 0.5 ms duration) were presented to the upper arm of college student participants, preceded on some trials by a weaker shock (0.5 ms duration, at perceptual threshold) at the same location. Intense shocks elicited eyeblink reflexes, and these eyeblinks were inhibited by weak electrical prepulses. These data suggest that the inclusion of prepulses immediately preceding painful therapeutic shocks, such as those generated by an implanted cardioverter-defibrillator, might be capable of reducing the startle response generated by that therapeutic shock.