Switching jitter of avalanche gallium arsenide photoconductive semiconductor switch influenced by multiple avalanche domains.

The stability of synchronous operation is directly related to the time jitter of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS). In this work, a numerical model for the switching jitter of avalanche GaAs PCSS is established, and the impacts of triggering optical energy and bias electric field on the switching jitter are investigated numerically based on an equivalent bulk current channel. The proposed numerical model predicts well the changing characteristics of switching time as well as switching jitter, which has been demonstrated by the experimental results. On this basis, the theory of multiple avalanche domains is introduced to compare the domain evolutions influenced by the bias electric field and triggering optical energy. The results indicate that the reduction of switching jitter is significantly determined by the accelerated formation and evolution of avalanche domains, which provides a good explanation of the jitter mechanism of switching time.

A new solid-state LC-Marx generator based on saturable pulse transformer.

The saturable pulse transformer (SPT) and six stage LC-Marx generator are proposed in this solid-state system. In the experiments, the output voltage of 14.5 kV and the rise time of 720 ns are achieved when the isolation inductance is 35 µH and the primary capacitor is charged to 350 V. The output voltage is 4.1 times larger than the charging voltage on the single capacitor. For larger output voltage and shorter rise time, isolation inductance is changed with the high-voltage silicon stack, which is a kind of rectifier diode consisting of several diodes enclosed in the resin with larger inverse voltage. In the same experiment condition, the output voltage is increased to 17.5 kV, which is 5.0 times larger than the voltage on the charging capacitor. The rise time gets down to 500 ns. The results show that the high-voltage silicon stack can further enhance the working performance of the SPT LC-Marx generator on the output voltage and rise time. Finally, experiments are carried out to test the working performance of the SPT LC-Marx generator at a repetitive frequency. The results show that the output voltage reaches 12 kV, which proves that the generator can work stably at 1 Hz.

Solid-state pulse forming module with adjustable pulse duration.

A new solid-state pulse forming module is described in this paper. The pulse forming module is fabricated on a glass ceramic substrate, with the dimension of 250 mm × 95 mm × 4 mm. By changing the copper strips used in the pulse forming modules, the pulse duration of the obtained pulsed can range from 80 ns to 140 ns. Both the simulation and tests show that the pulse forming module has a good pulse forming ability. Under a high voltage in microsecond's time, the new pulse forming modules can hold off a voltage up to 25 kV higher than that of the previous study. In addition, future optimization for the field enhancement near the thin electrode edge has been proposed and simulated.

A compact 100 kV high voltage glycol capacitor.

A high voltage capacitor is described in this paper. The capacitor uses glycerol as energy storage medium, has a large capacitance close to 1 nF, can hold off voltages of up to 100 kV for µs charging time. Allowing for low inductance, the capacitor electrode is designed as coaxial structure, which is different from the common structure of the ceramic capacitor. With a steady capacitance at different frequencies and a high hold-off voltage of up to 100 kV, the glycol capacitor design provides a potential substitute for the ceramic capacitors in pulse-forming network modulator to generate high voltage pulses with a width longer than 100 ns.

Influence of different illumination profiles on the on-state resistances of silicon carbide photoconductive semiconductor switches.

Characteristics of a silicon-carbide (SiC) photoconductive switch under different illumination profiles are presented. We triggered a V-doped semi-insulated 6H-SiC switch with lateral geometry using a laser beam of 532-nm wavelength. Photoconductivity tests for different spot profiles and locations show that such switches achieve a minimum on-state resistance when the switching gap is illuminated. The differences between on-state resistances are small for various partial illuminations of the switching gap. Semiconductor modeling is used to simulate the electric field and current profiles for different partial illuminations. The simulation results show poor on-state switch performance when partially illuminated. Based on these results, a more revealing circuit model for the switch matches well with experimental results for partial illuminations.