| Pseudospark switch is an important pulsed power switches and developing high hold-off voltage,high peak current low jitter and high repetitive frequency pseudospark switches are crucial to the development of pulsed power technology. In the paper, a systematic research is carried out on the pseudospark switch with glow discharge trigger, based on theoretical analysis,particle simulation and experimental investigation.1. The glow discharge trigger method has the following merits:long life time,stabilization,low glow pre-discharge voltage. In the paper, a cylindrical hollow cathode glow discharge cavity is designed, then particle simulation and experimental research are carried out. Particle simulation shows that the cathode voltage drop holds the primary anode voltage drop. In the cathode voltage drop zone, the ion density is bigger than the electron density and the net charge density is constant; and the e-field is axial symmetry. The experiment indicates:when the gas pressure 1Pa3.6mA, the discharge mode is abnormal glow discharge.2. The initial discharge process of pseudospark switch has been simulated via particle-in-cell plus Monte-Carlo collision method and the initial plasma density in the switch cathode cavity adopts non-homogenous distribution. The pseudospark discharge process mainly consists of Townsend process,virtual anode formation and expansion,hollow cathode effect and main discharge process. The virtual anode formation and expansion and hollow cathode effect are critical for the conduction, and it affects the conduction process of the switch directly. If the electrode borehole diameter is too small, such asφ≤2mm, the virtual anode is difficult to reach the hollow cathode cavity, the hollow cathode effect is weaken and the switch can hardly be conducted. Make sure the switch was not broken down; the parameters: such as the helium pressure,electrode borehole diameter electrode distance and initial plasma density were varied and their effect on the conduction time delay was investigated. The simulation results show that as the parameters increase, the conduction time delay decreases, which is consistent with the experimental results.3. The hold-off voltage is strongly depended on gas pressure and electrode distance. As the gas pressure increases, the hold-off lessens quickly; which is in accord with the Paschen law. The hold-off voltage of the pseudospark switch with 3 mm borehole diameter and 4 mm electrode distance is about 85% of that of the switch with the borehole diameter and electrode distance of 3 mm. When the borehole diameter and electrode distance are 3 mm; as the gas pressure decreases, the hold-off voltage has an upper limit of 40 kV; which is consistent with the Schoenhuber's research result 13.4 kV/mm on planar electrode. Experimental results show the electrode materials(such as brass,stainless steel and tungsten-copper alloy)have little effect on the hold-off voltage and can be omitted. The hold-off voltage characteristics of pseudospark switches with electrode outer-diameterφ=46mm andφ=8.8mm are also presented in the paper. The investigation results show that at the same gas pressure, the hold-off voltage of the smaller diameter is higher than the larger diameter's.4. Time delay and jitter are the description of the working stabilization of the pseudospark switches. The design and development of short time delay,low jitter pseudospark switches are important to the development of pulsed power technology. In the paper, the influences of working parameters on the time delay and jitter of the switch were carried out. The research indicates, as the glow discharge current,gas pressure and trigger voltage increase, the time delay and jitter decrease and then become saturated. Different to the high voltage gas spark switches, when the gas pressure p=12Pa, glow discharge current i=0.7mA, trigger voltage Vt=5.8kV; in the range of 8 kV to 25 kV, the time delay and jitter are approximately invariable as the anode voltage increases.5. The pseudospark switch has a wide working voltage range. When the glow discharge current i≈0.6mA, gas pressure p=10Pa, the trigger voltage up to some extent; the pseudospark switch can be triggered reliably from the voltage 400 V to 35 kV. Except that, the impact of electrode materials on the switch life time is also researched. Comparing the brass,stainless steel and tungsten copper alloy electrode; the tungsten copper alloy electrode has the longest life time, next stainless steel electrode, and the brass electrode is more likely to be eroded.6. The glow discharge characteristics of pseudospark switch in the air shows: the whole electrode gap is filled with soft glow, from the cathode to the anode, the color of the glow is pink,blue; which is consistent with the description of glow discharge theory. 7. Experiment shows:It is not suitable to use float middle electrode to form two-staged pseudospark switches. For the switch has the following shortcomings: at high gas pressure, the switches can only withstand low voltage; and at low gas pressure, the two gaps can not be used fully and triggered easily. While the two gaps can be used sufficiently and the switches can be triggered more easily, if the RC voltage even assignment is adopted. The reasons of the deformation of the trigger wave and occurrence of high frequency flaw are analyzed; and the period of high frequency flaw is computed, which is accord with experimental results. Also, the cause of the appearance of the positive anti-peak was analyzed and the method of suppression of the anti-peak was raised. |
