Xie Weiping

Initial Performance of the Primary Test Stand

The primary test stand (PTS) is a multiterawatt facility with a current of 8-10 MA and rise time of 90 ns, which is being built for Z-pinch studies at the Institute of Fluid Physics, China Academy of Engineering Physics. The PTS consists of 24 modules that are connected in parallel. Each module is based on the Marx generator and water pulse forming line as well as laser-triggered spark gap switch working at 5-MV level. The nominal total stored energy of the PTS is 7.2 MJ. All the Marx generators and laser-triggered spark gap switches had been tested at full voltage level before the PTS was assembled. The design and installation of the PTS are described. In this paper, the most recent results of the PTS commissioning will be introduced.

Overview of Pulsed Power Research at CAEP

Pulsed power research for military and civil applications has been conducted at the China Academy of Engineering Physics (CAEP) for more than 50 years. The pulsed power research activities include development of pulsed power components, such as different kinds of high-voltage switches, series of pulsed power sources and pulsed X-ray machines, high-current accelerators for Z-pinch and flash X-ray radiography, as well as medical application and electromagnetic launch. The most recent progress of pulsed power research at CAEP will be presented.

Ultrafast 10kV SiC PCSS and its on-state Characteristics

Summary form only given. Vertical geometry PCSSs (Photoconductive Semiconductor Switches) with opposing electrical contacts were fabricated using 0.4mm thick, vanadium compensated, semi-insulating, 6H-SiC (Silicon Carbide) “c”-plane wafer. Ultrafast photocurrent waveforms were obtained when the switches were illuminated laterally by <100 ps pulse width, 1064nm wavelength laser. The risetimes, falltimes, and widths of photocurrent waveforms are all ∼1ns. The ultra fast characteristics of the SiC PCSSs can be owned to the very short carriers lifetime of the SiC crystal. The SiC PCSSs were tested up to a bias voltage of 11 kV with the corresponding peak current is 90 Amperes. The 6H-SiC PCSS chips can withstand average electric field up to 27.5kV/mm. This value though is much lower than the theory breakdown electric field of 300kV/mm, but is much higher than one (∼3kV/mm) of earlier designed lateral geometry surface SiC PCSS. One reason is that, present opposing-electrical-contacts design is out of enormous electric distortion of opposing blade electrodes in lateral geometry surface switches, and prohibits surface flashover. Another reason can be attributed to that the small area electrodes design can avoid micropipe defects, which are vertical to and penetrate “c”-plane wafer, then tend to lead early breakdown. The minimum on-state resistance of about 21Ω was obtained with ∼2mJ triggering laser energy.

A Multiplex Multi-Stage Surface Flashover Switch

A new type of surface flashover switch, suitable for multiplex pulse generation, is studied. The switch is composed of several parallel rail gaps (PRGs). Each multistage PRG is composed of several serial subgroup gaps (SSG) formed by intermediate electrodes. The trigger electrode of the switch is a common electrode isolated from the main discharge circuit and located parallel to the central line of PRGs. The multistage scheme of PRG is helpful to multi-channel discharge. The switch has some advantages, such as a low jitter, low conduct inductance and short switching time. These advantages and the multiplex scheme make the switch suitable for short frontal rising time pulse formation and accurate synchronization for a multi-module parallel operation device. In a primary test, the jitter of the switch is about 3.3 ns. It has been applied in a linear transformer device successfully.