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A pulsed power supply of a 1.5-MJ capacitor bank has been developed for high-current high-velocity sliding electrical contact studies in railgun launches. The system consists of 8 small modules, each with a capacitance of 15 mF, and one large module with a capacitance of 54mF. All of nine modules use triggered spark gaps as the main switches. Various shapes of high-current pulse can be formed by controlling the charging voltage and firing time of each module. The small module has been designed for the maximum operating voltage of 5 kV, the peak current of 140 kA, the pulse rise time of 0.9 ms, in which semiconducting diode stack is used as crowbar switch. Since the large module has no crowbar switch and relatively small pulse forming inductance, it can supply high-amplitude oscillating current waveform. The effects of the large module are threefold. First, the large module provides a basic current on which the currents of small modules superimpose to form a nearly constant driving current of armature. Second, the oscillating nature of the current can drastically reduce the muzzle arc current; hence suppression of the muzzle arc can be obtained. Third, the crowbar switch can be removed and therefore the cost of the system can be reduced. The experiments were performed to verify the operation performances of the two kinds of modules, where the modules were discharged simultaneously and/or sequentially. The feasibility of large module on the muzzle arc control is also examined. The results of the experiments show that a total current of 400 kA with a 1.5 ms flat-top time can be obtained and all the modules show good performance during the railgun firing. Index Terms--Capacitor bank, electrical sliding contact, pulsed power supply, railgun.

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 Electromechauical 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. Index Terms--PSL armature, pulsed power supply, rail launcher, transition.

The unique properties of the plasma utilized in ETC guns, such as the low viscosity, high momentum and high temperature, can lead to a more uniform ignition over the entire cartridge volume, even in large-caliber guns. Since 2002, the united research group leaded by Beijing Institute of Special Electromechanical Technology (BISET) has completed a lot of experiments with a novel surface discharge plasma igniter, which generates plasma from a cylindrical surface and distributes it through radial port. The results of these experiments have shown this igniter can present perfect ignition. This paper presents an overview of this ETC program including the igniter, pulsed power supply, 120 mm ETC launchers, and some experimental results. The further experimental studies are being continued. Index Terms--Electro-thermal chemical, gun, plasma ignition.

A 3-m-long 30-mm square bore launcher has been constructed for electromagnetic launch application at the Institute of Electrical Engineering, Chinese Academy of Sciences. The main purpose of the launcher is to conduct the basic and applied research in electromagnetic launch. An optimum structure of the insulators was adopted through the stress analysis using the software ANSYS. In order to know about the variation of the gap under a certain stress, an air pressure piston (maximum air pressure of 5 MPa) and a position sensitive detector were adopted. The measuring results have shown that the rail gap decreases gradually from breech to muzzle; this kind of design can abate the erosion of the rails caused by arc discharge effectively. A total of 85 tests has been performed, including 17 tests of single-module discharging and 68 tests of nine-module sequential discharging, and a highest muzzle velocity of 1.9 km/s with a 45-g mass was achieved, operating at a current of 410 kA and 2-ms pulse duration. This launcher is now used for the fundamental research on armature structure, performance of the pulsed power supply, and the diagnostic system. A novel launcher based on the previous experimental results is under development. Index Terms--Armature, insulators, rail, stress analysis.

Armor vehicles have traditionally been protected by the armor based on steel. This gives rise to extremely heavy structures which produce logistic problems due to the need to transport the vehicle to a battle field [1]. Many kinds of technique have been developed to meet this change. A new concept--Active Electromagnetic Protection System (AEMPS) has the advantage of short trigger delay time, good controllability, repetition uniformity and convenient logistic service. So it must be the development trend of the active protection system. At present, there is not much research on the effect of AEMPS. In order to better understand the effect of AEMPS, establishing a numerical model to simulate the interception process is required. In this paper, taking pole armor piercing projectile as example for it has heavy threat on armor, numerical simulation was performed with the finite element software LS-DYNA3D. The simulation shows good result. After being intercepted, pole armor piercing projectile's warhead turns blunt and inflected, its velocity slows down and the ability to penetrate the same armor decreases about 20-25 percent. Good practical effect of AEMPS is based on intercepting target successfully. Since pole armor piercing projectile has high velocity, it requires that AEMPS has high accuracy of interception. In order to evaluate the launching direction accuracy, a new launching apparatus was made and the accuracy test was carried out in the laboratory. The experimental result showed that the direction accuracy of launched interceptor is less than 0.5 degree. So it can intercept target successfully in the range of five meters. Index Terms--Accuracy, AEMPS, effect, numerical simulation.

This paper describes preliminary experiments conducted at zero speed using the pseudo-liquid armature with air-spring. Measurements made during these experiments include current, muzzle voltage, and gas pressure in the air spring. Armature action was obtained by simulating the current pulse. From this specific action was obtained by using the actual armature conducting area. The results obtained for the seven experiments conducted are presented. We discuss the results and make recommendations for future work in this area. Index Terms--Aluminum pseudo-liquid armature, arcing resistance, muzzle voltage, rail surfaces, transition into arcing contact, zero speed.

For basic research on electromagnetic launch technology, the Beijing Institute of Special Electromechanical Technology has initiated a program focusing on the design and testing of a 10-MJ electromagnetic launcher facility with the cooperation of Nanjing University and the Institute of Electrical Engineering, Chinese Academy of Sciences. The facility will consist of a 10-MJ prime energy, a 6-m-long railgun, and a control system. A 3.2-MJ pulse power unit (PPU) with 32 100-kJ modular PFN units has been completed and tested, and its prime energy can be easily extended to 10 MJ. A 6-m-long railgun has been built, which can be easily cut into a 4-m-long railgun by which many firings have been done with the new PPU. Construction and testing of the whole facility are being continued. [ABSTRACT FROM AUTHOR]

Renewed interest has arisen in plasma armatures as evidenced by two papers presented at the 2008 EML Symposium. It is hoped that the work at the University of Texas described in these papers succeeds. There may, however, be some uncertainties related to the nature of plasma armatures in that work. The thoughts we offer here may help. It is not yet obvious how the 6-km/s velocity limit encountered in the Canberra railgun can be overcome. In the years following this discovery, a considerable number of experiments were conducted on the subject with no clear outcome. One strategy for overcoming the velocity limit may be to vent the bore behind the armature. In order to do this, it is necessary to find out how long the armature must be to be effective. Too long would make the venting process unwieldy. Too short and the armature losses will rise to unacceptable levels. Further, the method we suggest for implementing the venting strategy may be extended to prevent damage to the railgun rails caused by the arcing current transfer from rails to armature. We examine the possibilities and implications involved in implementing these strategies. [ABSTRACT FROM AUTHOR]

In this paper, we present a method of photoelectric conversion and fiber transmission to measure the respond time and its accuracy on an active electromagnetic protection system (AEMPS). The measurement results are that the respond time of the AEMPS is 46.76 \mu\s and that its diffuse time is less than 3 \mu\s. However, the error of the projectile's initial velocity is the key factor influencing the time accuracy of the AEMPS. According to the result, it has a very fast respond time and a high accuracy. The AEMPS has a certain mission success rate to intercept the assaulting target if the target detection has enough accuracy. [ABSTRACT FROM AUTHOR]

A multiturn railgun was designed to obtain high inductance gradient. It was made up of two pairs of copper rails. These two pairs were arranged up and down in space and were separated by the insulating structures. Each pair was an independent circuit with its own armature conductor. They were connected serially at the breech with a crossover. The two parallel armatures constitute the projectile with an insulating container. The bore size was 30 mm \times 60 mm. The rails were tightened with two pairs of insulating wedges against insulating spacers. Two up and down wedges constituted a frictional pair. The upper wedges would move down when the barrel containment was tightened gradually through the bolts, and they would produce enough preload to the rails to keep the gaps of each rail pair to 30 mm. The magnetic field in the barrel was simulated, and the mean inductance gradient was estimated to be 1.3 \mu\H/m. The B-dot probes were also installed to diagnose the movement of the projectile in the barrel. Launch experiments with a peak current of 299 kA were conducted to test the performance of this two-turn electromagnetic launcher. [ABSTRACT FROM AUTHOR]

To analyze the stored-to-kinetic energy conversion efficiency, a transient electric-circuit model for a railgun system is built using the electrical circuit analysis software SIMPLORER in this paper, and the electric parameters of the model are defined with measurement values of the actual system. Many results of simulations and experiments are also presented, and the results show that the equivalent series resistance of the coaxial cables and the rail resistance are major factors on the energy conversion efficiency. In the end, some methods are proposed to improve energy conversion efficiency of the pulsed-power supply system. [ABSTRACT FROM AUTHOR]

The pseudoliquid (PSL) armature with air spring is a novel railgun armature which has been fired successfully many times in a simple railgun by a united research group led by Beijing Institute of Special Electromechanical Technology (BISET), and the results of these experiments show that this armature can prevent transition in some conditions. Multiple turns in a railgun can significantly increase the inductance gradient of the launcher and decrease the needed current. Therefore, BISET initiated a program to launch projectiles with PSL armatures by a two-turn railgun. This paper presents an overview of this program, including the pulsed-power supply, a two-turn rail launcher, projectiles, and some experimental results. Further experimental studies are being continued. [ABSTRACT FROM AUTHOR]