A supersonic nozzle for a 1.5-MA gas puff pinch was designed and the gas flow injected out from the nozzle was measured. A miniature ionization gauge was developed to measure the density profile of the gas shell and two pressure transducers were used for determining the Mach number of the gas flow. It was found that the gas flow is not distributed symmetrically about 0, the mean radius of the exit aperture, and the radial location for the peak of the density profile moves inwards as time goes on. When the plenum pressure is 5atm, the maximum line mass density measured was 43g/cm and the Mach number of the gas flow deduced from experiments is 4.3, which is close to the expectation: a line mass density of about 50g/cm and a Mach number higher than 4. The measurements indicate that if a plenum opens into a large dead volume via a finite opening valve in a gas-puff system it will not produce a steady-state solution. Then, any agreement between the measurements and the calculations based on the steady state should not be expected.

A three-frame Mach-Zehnder interferometer TFMZI was developed for taking three pictures of the imploding plasma produced by one shot of fast pulsed discharge. TFMZI consists of a YAG laser, a beam splitter, and a Mach-Zehnder interferometer. By passing through the beam splitter the laser beam was split into three beams with an interbeam delay of 13ns and each laser beam will give a snapshot of the implosion state. The measurements with the TFMZI were conducted on a small gas-puff z-pinch device and gave good results. In principle an upgraded four or more frame Mach-Zehnder interferometer could be constructed if much improvement was made on the TFMZI.

The gas discharge in a gas peaking switch was experimentally studied and numerically simulated. For simulation, the discharge was divided into two phases, gas breakdown and voltage collapse. The criterion for an electron avalanche to transit to streamer was considered as the criterion of gas breakdown. The spark channel theory developed by Rompe-Weizel was used to calculate the spark resistance. It was found that the prepulse considerably lowers the voltage pulse applied to the gap. Even for a given input pulse, the voltage pulse applied to a peaking gap is different for different gap distance due to existence of a different prepulse. In this case, the breakdown voltage of a gas peaking gap depends on gas pressure and gap distance, individually. For nitrogen pressure varying from 3 MPa to 10 MPa and gap distance from 0.6mm to 1.2mm, the peak electric field higher than 2MV0cm was achieved when breakdown. The output 10% to 90% rise time, tr, varies from 145ps to 192ps. As gas pressure increases, trdecreases, which can be explained by the fact that the breakdown field increases with the increase of gas pressure. It was found in experiment that the jitter in tr could be attributed to the jitter in breakdown field. Instead of getting longer, the averaged experimental tr gets shorter as gap distance increases from 0.6mm to 1.2mm, which differs from the results of calculation and indicates there may exist something, other than electric field, that is also related to tr. The reason for this difference may lies in the inverse coefficient of spark resistance varying with gap distance. On the whole, the results from the calculations agree with the experimental ones.

A small neon gas-puff z-pinch device was constructed, and the plasma implosion and its radiation characteristics were studied experimentally. The plasma implosion was investigated using a three-frame Mach-Zehnder interferometer (TFMZI) that is capable of taking three pictures (5ns exposure and 13ns interpicture delay) within a single z-pinch shot. Thermopiles were also used in the experiments with the TFMZI to study the correlation between the total energy of x-ray emission and the plasma implosion. The ion beams from the z-pinch plasma were analysed using a compact Thomson spectrometer. Based on the experiments, the imploding velocity and electron density of the plasma shell were obtained, a conclusion that a nearly uniform and symmetric imploding plasma shell would emit a higher x-ray yield than an asymmetric one was drawn and the charge state resolved energy spectra of ion beams emitted from the z-pinch plasma were plotted.

The cavity structure of the anode and the cathode of a pseudospark switch is an important factor for its performances. When the cathode has a cavity structure, the electric erosion on the cathode and anode is small and a concentric ring-shaped erosion pattern is observed at the central area around the apertures of both electrodes. Without the cathode cavity, the erosion becomes stronger, and the patterns become irregular and unstable. Several kinds of electrode structure have been designed and investigated. Among them, a unique cavity structure of intermediate floating electrode in pseudospark switch has a good performance. This configuration could reduce the erosion on the electrodes and increase the selfbreakdown voltage of the pseudospark switches up to 80kV. In this paper, we have studied the influence of the electrode structure on the erosion of the electrode and the selfbreakdown characteristic of the switches.