Yaohong Sun

Comparative study of NO removal in surface-plasma and volume-plasma reactors based on pulsed corona discharges.

Nitric oxide (NO) conversion has been studied for two different types of atmospheric-pressure pulsed-corona discharges, one generates a surface-plasma and the other provides a volume-plasma. For both types of discharges the energy cost for NO removal increases with decreasing oxygen concentration and initial concentration of NO. However, the energy cost for volume plasmas for 50% NO removal, EC(50), from air was found to be 120 eV/molecule, whereas for the surface plasma, it was only 70 eV/molecule. A smaller difference in energy cost, but a higher efficiency for removal of NO was obtained in a pure nitrogen atmosphere, where NO formation is restricted due to the lack of oxygen. For the volume plasma, EC(50) in this case was measured at 50 eV/molecule, and for the surface plasma it was 40 eV/molecule. Besides the higher NO removal efficiency of surface plasmas compared to volume plasmas, the energy efficiency of surface-plasmas was found to be almost independent of the amount of electrical energy deposited in the discharge, whereas the efficiency for volume plasmas decreases considerably with increasing energy. This indicates the possibility of operating surface plasma discharges at high energy densities and in more compact reactors than conventional volume discharges.

High Power Capacitor Charging Power Supply for EML Applications

A compact high-power high-voltage capacitor charging power supply (CCPS) has been developed based on series resonant inverter technology for 1 MJ electromagnetic launch system. Multiple practical protecting measures are designed and adopted in the CCPS which can prevent many malfunctions occur. At the same time a series of measures are adopt to increase the power density. The experimental results have shown that the peak power and the power density of the CCPS are 40 kW and 0.49 W/cm3 respectively.

Compact, Nanosecond, High Repetition Rate, Pulse Generator for Bioelectric Studies

The high dielectric strength and high permittivity of water allow for its use for energy storage and switching in compact pulse power systems. A 10-Omega pulse generator with flowing water as dielectric and as the switching medium is presented here. It can provide a 10-ns pulse with a risetime of approximately 2 ns and an amplitude of up to 35 kV into a matched load. The system was operated in burst mode with repetition rates of up to 400 Hz, limited by the charging power supply. For a switch with two pin electrodes, strong electrode erosion limits the use of the pulser to less than 1,000 pulses before electrode readjustment is necessary. A considerable reduction of the erosion effect on breakdown voltage was obtained with coaxial electrodes. The pulse generator was used to study the effect of the repetition rate (or the time between successive pulses) on the viability of B16 murine melanoma cells.

High-Voltage Repetition-Frequency Charging Power Supply for Pulsed Laser

With the wide use of laser in industry, agriculture, medical, and military, the requirement of its preceding excitation power supply is also getting higher and higher. In this paper, a high-voltage repetition-frequency charging power supply used for pulsed laser is described, which uses the principle of series resonant and power electronic conversion. A high-frequency high-voltage transformer and a high-voltage silicon rectifier are also used to obtain a dc voltage, whose output power can reach up to 20 kW. The control system of the power supply is based on the digital signal processor, so that the output voltage can be regulated between 0 and 30 kV, and the repetition frequency can be regulated between 1 and 100 Hz. Some other functions have been designed, such as the two control modes of remote control by PC and local control by keyboard. To extend the application of this power supply, an external trigger control interface is also provided for the synchronization control of the power supply and other equipment of the pulsed laser system. In the experiment, the power supply that described in this paper was used as the preceding excitation power supply of the pulsed laser. The results of the experiment show that the power supply can work effectively.

Simulation of Partial Discharges in Single and Double Voids Using SIMULINK

Partial discharges (PD) in the insulation of power equipment have been a focal point in the field of electrical technology. Numerical simulation of PD is an important approach to knowing the PD mechanics. In this paper, the physical model of PD in voids was modified and the simulation circuit of PD in voids was built using Simulink. The simulations of the epoxy resin samples with a single void and double voids were investigated, respectively. The discharge voltage waveforms, discharge current waveforms, and the single discharge waveforms of voids were obtained by simulation. At the same time, we measured the PD pulse waveforms of epoxy resin samples in time-domain by an ultra-wideband PD measuring system. The test samples enclosing artificial voids have the same size as the simulation samples. The single discharge waveforms of a single void and double voids obtained by simulation are very similar to the measured ones in the same condition. Moreover, the different discharge rules between one void and two voids are found by simulation. The conformity of the simulation results and test ones indicates that the simulation model is effective and the simulation results are reliable

High-Voltage High-Frequency Charging Power Supply Based on Voltage Feedback and Phase-Shift Control

With the rapid development of the electromagnetic launch technology, the performance requirements for the charging power supply are increasing. To control the charging rate accurately and get the steady load voltage, a phase-shift control system was designed. This system adopted the control method which regulates the phase angles of the driving pulses by calculating the relationship of the voltage feedback and the preset charging time. According to the topology and application requirements of a high-voltage high-frequency charging power supply (HVHFCPS), a simulation platform based on the physical security information management software was set up. A prototype of HVHFCPS based on voltage feedback and phase-shift control was developed. The experimental results show that the load voltage can be controlled accurately.

Research on the Sliding Electrical Contact of the Rapid Fire Railgun

The sliding electrical contact between the armature and the rails is affected by the high driving current and the friction heating during the launching process, especially in high fire rate applications. The contact performance is closely related to the impedance between the armature and the rails. A rapid fire railgun was designed for this paper of the sliding electrical contact. The pulsed power system consists of ten 100 kJ pulse forming units with a total stored energy of 1 MJ, and the length of the launcher is 1310 mm with a caliber size of 18 × 18 mm. Two types of armatures are adopted, a C-shaped armature and a double C-shaped armature. Two 5 g armatures can be launched at a frequency of 166 Hz with a muzzle speed of 800 m/s. The effect of contact impedance by the temperature rise can be calculated approximately with heating. Experimental results show that the contact impedance is seriously affected by the electromagnetic force and the contact temperature; the contact impedance of the second armature is 0.8-2.6 mΩ, which is higher than that of the first armature (0.2-0.3 mΩ).

Recent Pseudo-Liquid Armature Experiments with Details of the Test Systems

The pseudo-liquid (PSL) armature with air-spring is a novel railgun armature, which has lower mass and more compliance than conventional C-shaped armature. The united research group leaded by Beijing Institute of Special Electromechanical Technology (BISET) has completed a lot of experiments of the PSL armatures with air-spring since 2004. The results of these experiments show this armature can prevent transition with some conditions. This paper presents an overview of PSL armature program including the pulsed power supply, two rail launchers (SRL1 and SRL3), projectiles and some experimental results. As the best result of SRL1 rail launcher tests, it is obtained that muzzle velocity of 1.1 km/s with a 52 g mass. The best performance of SRL3 launcher tests is muzzle velocity of 1.92 km/s with a 45 g mass operating at a stored energy of 1.39 MJ and a flat-top current of 400 kA with about 1.5 ms pulse duration. The further experimental studies are being continued.

High-Voltage high-frequency charging power supply based on voltage feedback and phase-shi control

With the rapid development of electromagnetic launch technology, the performance requirements for the charging power supply are increasing. To control the charging rate accurately and get the steady load voltage, a phase-shift control system was designed. This system adopted the control method which regulates the phase angles of the driving pulses by calculating the relationship of the voltage feedback and the preset charging time. According to the topology and application requirements of high-voltage high-frequency charging power supply (HVHFCPS), the simulation platform based on the PSIM software was set up. A prototype of HVHFCPS based on voltage feedback and phase-shift control was developed. The experimental results shown that the load voltage can be controlled accurately.

Simulations on Elastoplasticity of the Monolithic Aluminum Armature Under the Contact Force

Keeping good contact of the armature-rail interface (ARI) is essential for electromagnetic launch technology. To investigate the contact mechanism of ARI and improve the contact condition, the elastic-plastic deformation of the monolithic aluminum armature (MAA) under the contact force is analyzed. Contact force, contact area, and the distribution of contact pressure are calculated, and several kinds of armatures with different arm lengths are compared under the same conditions. The calculating loads include the pretightening force under the initial preload and the electromagnetic force from the pulse current. The simulation results show that both the contact force and the contact area under the plastic deformation are bigger than those under the elastic deformation, which is due to the higher spring-back force and displacement. A longer arm length can result in better flexibility and lower contact force. The effect of the electromagnetic force versus the contact force is increased with the arm length.