The properties of switching transient in the gallium arsenide photoconductive semiconductor switch (GaAs PCSS) are significant for improving the device lifetime. In this article, the properties of switching transient in the opposed-contact semi-insulating (SI) GaAs PCSS, including the physical process of the ultrafast switching, the characteristics of delayed breakdown, and the current density distribution, are studied, based on an effective 2-D, time-dependent numerical model. The numerical results demonstrate that there exists a positive feedback loop between the increase of the carrier density and the formation and evolution of the avalanche domains, which achieves the ultrafast switching of the opposed-contact SI-GaAs PCSS. The higher bias voltage and triggering optical intensity can promote the earlier formation of the avalanche domains and accelerate the evolution of the domains, leading to a shorter delay time and switching time. The triggering positions determine the distribution of the avalanche domains in the opposed structure, affecting the delay time, among which the cathode triggering leads to the shortest delay time. Current crowding in the opposed structure mainly occurs in the vicinity of the contacts, which first damages the edges of the contacts and makes the areas near the contacts present different failure characteristics. Our analysis indicates that anode triggering is effective for suppressing the current crowding to improve the lifetime of the opposed-contact PCSS.

The switching transient of gallium arsenide photoconductive semiconductor switch (GaAs PCSS) undergoing the transition from linear mode to nonlinear mode is investigated based on a “two-channel” model. Excellent agreement between the simulated and the experimental output waveforms is achieved first in the study of this transitional mode. The numerical results have revealed that a competitive relationship exists between the switching and nonswitched channels of the PCSS, and the formation and evolution of avalanche domains boost the nonlinear mode developing in the switching channel to win out from the linear mode dominated by the nonswitched channel. Based on the numerical model, the effects of the cross section of current channel on the output characteristics are well analyzed and discussed, which have also been demonstrated experimentally.

The high power pulse generators have been widely used in high power microwave generation and plasma physics research. In this paper, a novel compact solid-state high power pulse generator is studied, numerically and experimentally. The generator is mainly composed of the primary energy supply, the magnetic pulse compressor, the Blumlein type low-impedance pulse forming network, and the square waveform pulse transformer. Especially, design considerations for a solid-state high power pulse generator are proposed. Experimental results show that pulses with a peak power of 2 GW, a duration of 150 ns, and a repetitive rate of 10 Hz are continuously achieved on a dummy load. The dimension is Φ60 × 210 cm², and the average power density reaches ∼5 W/L. Experimental results show reasonable agreement with numerical analysis.

We demonstrate the positive role of an optical internal reflection structure (OIRS) in improving the on-state performances of gallium arsenide photoconductive semiconductor switch (GaAs PCSS). Herein, the structure consisting of a convex lens and two reflectors creates an effect of increasing the extrinsic absorbance. Under the same laser input, the PCSS employing this structure has achieved higher voltage output, faster switching and lower on-state resistance, which demonstrates at least 1.5-fold improvement in triggering efficiency, compared to the normal device. A two-dimensional (2D) device simulation has been performed and reveals that the positive effect of the OIRS is attributed to the accelerated formation of avalanche domains and the heightened carrier concentration, which are affected by the increased optical absorption.

The meander pulse forming line (PFL) is a kind of prospective solid dielectric device for compact, reliable pulsed power systems. In this paper, the electrode structure of a PFL based on glass ceramics was designed with a Ω-shaped structure, which can improve the voltage strength of the PFL and increase the output pulse width. The electric field distribution and output waveform were obtained numerically. Experimental results illustrate that the improved PFL, with dimensions of 260 × 140 × 7 mm³, when used as a simple PFL could generate a well-shaped quasi-square pulse, with the output pulse duration of 85 ns, which is in agreement with the simulation within 14%. Under the conditions of 30 kV charging voltage, 50 Hz repetition frequency, and 4 Ω matching impedance, the lifetime of the solid dielectric PFL based on glass ceramics could be more than 1 × 10⁶. Experiments show reasonable agreement with numerical analysis.

A ceramic-based pulse-forming line (PFL) is a solid-state device with a wide range of applications in compact pulsed power systems. In this paper, the characteristic impedance of a ceramic-based PFL is theoretically analyzed, and an improved PFL based on an impedance matching electrode is proposed. The improved PFL effectively increases the flat-top ratio and reduces the rise and fall times, enhancing its potential applicability. Experiments using the improved PFL show that, under a charging voltage of 33 kV and with an impedance matching load, the output pulse width can reach 86 ns with a matching impedance of 3.9 Ω. The improved PFL output waveform has a flat-top ratio that reaches 72%, compared with 49.5% in a typical PFL, and exhibits shorter rise and fall times.