Search

Railguns are current-driven guns that allow reaching large muzzle velocities and energies. In the military context, the long-range artillery scenario makes use of these two capabilities to enable the launch of hypervelocity projectiles to target distances above 100 km. As of today, the most advanced railgun project is conducted by the Office of Naval Research, Arlington, VA, USA, and features railguns with a muzzle energy of 32 MJ. Such large artillery railgun systems with efficiencies above 30% are fed by a pulsed power system with a nominal energy content of about 100 MJ. In contrast to this, experiments with French-German Research Institute’s (ISL) most powerful railgun, PEGASUS, have reached muzzle energies of 2 MJ, only. The nearer future ISL has to answer two questions: 1) is the railgun technology adequate for a long-range artillery scenario? 2) can the railgun launch a hypervelocity projectile which is being developed by other groups in ISL? To do so and to support the development of the hypervelocity projectile, a larger railgun installation with a significant increase of the energy and free flight capability is required. In this paper, three different railgun systems were investigated using an electric circuit simulation code. The systems are referred to by the energy being stored in the capacitors as 25, 50, and 100 MJ. The aim of this paper is to investigate what masses can be accelerated to the relevant velocity range for the long-range artillery scenario by these different primary energies. The results of this paper can be used to aid the decision about the required size, with respect to the military scenario, of a potential future railgun system. [ABSTRACT FROM AUTHOR]

A new modular pulsed-power source with fast rise time and step-wise arbitrary output waveform generation is currently under development to drive the Gepulste Elektronenstrahlanlage device investigated at the Institute for Pulsed Power and Microwave Technology (IHM). Acknowledging the complex design procedures necessary to set up a modular pulsed-power source for voltages of up to 120 kV, this paper focuses on the circuit design for a single stage and its validation prior to the generator assembly. Using a semiconductor-based Marx generator topology, the stages are designed to have an output voltage of 1 kV with a pulse current of up to 600 A. When connected to an ohmic load, the measured current rise times are in the order of 46 ns resulting in the current rise rates of up to 10 kA/ $\mu \text{s}$ using the commercial devices. The step-wise arbitrary output waveform is created by generating the switching commands on the stage using a microprocessor and a fast optical synchronization unit. Effective stage shielding is verified by operating the stage in a 100-kV, 2.5-kA electromagnetic interference test bed. This paper presents the design considerations and the corresponding measurements. [ABSTRACT FROM AUTHOR]

Based on the urgent needs for modularization and miniaturization of the inductive pulsed power supply system, this paper proposes the conceptual design and comparison of 100-kJ inductive storage power modules including four circuit topologies, three of which are proposed in our previous researches. The four circuit topologies are the STRETCH meat grinder, the XRAM with STRETCH meat grinder unit, the XRAM with strongly coupled inductors, and the XRAM with magnetic flux compression effect. The maximum load current of each constructed module is set to be 50 kA and its pulsewidth is at least 5 ms, which are the same as the main electrical properties of an existing 100-kJ capacitive module. A comparative study on energy density among the constructed inductive modules and the existing capacitive module is carried out in depth. Results show that the inductive modules, considering the volume of semiconductor switches and their control circuits, have higher energy density than that of the capacitive module. Among four constructed inductive modules, the XRAM with strongly coupled inductors module has the highest inductive energy density, and the XRAM with magnetic flux compression effect module has relatively better comprehensive performance. This paper offers the theoretical analysis foundation for investigating the inductive pulse power supply with higher energy. [ABSTRACT FROM PUBLISHER]

Superconducting pulsed-power supply (SPPS) provides an efficient method for both high-density inductive energy storage and high current pulse generation. An SPPS consisting of eight high-temperature superconducting pulsed-power transformer (HTSPPT) modules with XRAM methodology was designed and simulated in preliminary studies. It recycled the leakage flux energy and reduced the voltage across the opening switch with a capacitor in primary. However, the SPPS with XRAM methodology has two problems. The first one is that it can provide high pulse amplitude, but cannot provide enough width. The other one is that the ratio of the maximum capacitive energy over the total inductive energy is relatively large, which cuts down the overall system energy density. This paper proposes a modified topology of SPPS with capacitor reuse methodology. Multiple HTSPPT modules are divided into several groups. Each group shares the same capacitor. The procedure of the modified SPPS is presented in detail. A 270-kJ SPPS with capacitor reuse methodology is designed and simulated to illustrate the modified topology. With the load parameters of a small railgun, the peak value of the load current is 207.15 kA and the pulse half-height width is 5.56 ms, the ratio of the maximum capacitive energy over the total inductive energy is 11%. The characteristics of the modified topology are also described in detail in this paper. [ABSTRACT FROM PUBLISHER]

The superconducting inductive pulsed-power supply (IPPS) is considered to have broad application prospects in the field of electromagnetic launch because of its low electrical loss. In order to obtain a higher efficiency in continuous electromagnetic launch, a repetitive IPPS circuit topology based on a high-temperature superconducting pulse power transformer (HTSPPT) has been proposed in our previous studies. It can recover most of the remaining energy for generating continuous current pulses by using a bridge-type capacitive switching circuit. As a follow-up work, this paper presents a multimodule repetitive superconducting IPPS model for a railgun system. This multimodule model consists of 24 HTSPPT modules connected to an XRAM-like circuit topology. In order to verify the feasibility of the repetitive superconducting IPPS and study its driving characteristics, the dynamic launching process of a simple 4-m-long railgun system was simulated. The influence of the capacitance in the bridge-type capacitive switching circuit on the main performance of the system, such as the maximum output current, the maximum primary voltage, the launch efficiency, the maximum capacitive energy ratio, and the remaining energy recovery ratio, was analyzed. The simulation results show that the repetitive superconducting IPPS is suitable for driving the simple railgun. In addition, it also concluded that the system performances conflict with each other and the optimal capacitance value for each HTSPPT module should be determined by the tradeoff of system performances. [ABSTRACT FROM AUTHOR]

This paper presents a new capacitor bank topology for a pulsed power system to improve the efficiency of multistage synchronous induction coilgun. In the proposed method, a switch, such a gate turn-off thyristor, is inserted in parallel to a crowbar diode and load to generate an attractive force between the next stator and the armature. A mathematical model was developed, and finite-element method simulations were conducted to verify the proposed topology. The results show that the proposed method improves the energy efficiency and launch velocity. The improvement in energy efficiency is confirmed from the simulation results of a three-stage synchronous induction coilgun. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS), especially superconducting pulsed power supply (PS), has been the focus of research in recent years due to its high energy density and low power requirement for the input PS. Quite a lot of fantastic work regarding two or multiple IPPS modules has been presented. But they disregard the mutual inductance between modules. This paper establishes a double-module IPPS based on two high-temperature superconducting pulsed power transformers and takes the mutual inductance between modules into consideration. The influence of the mutual inductance between two modules on three discharge modes of the system is researched. Simulations and experiments on synchronous discharge, time-delay discharge, and asynchronous discharge are carried out, respectively. The results demonstrate that taking the mutual inductance into consideration, the amplitude and the pulsewidth of the output currents are both improved a lot, especially the obtainable energy of load is improved by nearly half. For time-delay discharge, the mutual inductance makes the delay time slightly increase. However, for asynchronous discharge, the mutual inductance increases the positive maximum value of the primary current of the second module. It may exceed the critical current and lead to quench. Consequently, the mutual inductance between modules has positive impacts on synchronous discharge and time-delay discharge of the IPPS system while it brings both advantages and disadvantages to asynchronous discharge. [ABSTRACT FROM AUTHOR]

Slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, which was proposed by the Institute for Advanced Technology, added a capacitor into the traditional meat grinder circuit. Even though its energy density is slightly less than the corresponding pure inductance system, it can reduce the voltage across the opening switch and maintain the high multiplication factor of the opening current. The performance of the STRETCH meat grinder circuit depends on multiple parameters. The inductance ratio ( n=L1 / L2) and the capacitance (C) are the two vital factors, which have a crucial influence on the system performance, such as the voltage over the opening switch ( V_{\rm Sopm}) , the current multiplication factor ( m$ ), and the ratio of the maximum capacitive energy over the total inductive energy ( $\eta )$ . Thorough studies have been carried out in this paper on the relationship between the above two factors and the three performance criteria. This paper also discusses and analyzes the chosen of the key parameters ( $n$ and $C$ ) for a single-stage STRETCH meat grinder with 2-mH total inductance, which is made up of two serial coils with 0.95 coupling factor. The opening current of the main switch is 1 kA, which constitutes a 1-kJ inductive pulsed-power supply. It fully takes the advantage of the STRETCH meat grinder topology, intensifies the study of the inductive pulsed-power supply with higher energies, and is easy to be utilized for practical application. [ABSTRACT FROM PUBLISHER]

In this paper, a compact all-solid-state pulsed power modulator was designed based on Marx generator and pulse transformer. It is consisted of a six-stage Marx generator using power MOSFETs as switches to generate primary voltage pulses and a pulse transformer through a closed magnetic core to boost and convert the polarity of the output high-voltage (HV) pulse. A MOSFET driver circuit based on optical–electrical isolation was designed for controlling the Marx generator. It shows that the output pulse shapes, especially the rising and falling phases, are determined by the design of the pulse transformer such as its leakage inductance, distributed capacitance, magnetization inductance, and step-up ratio. The designed modulator is able to generate HV pulses with amplitude ranging from −35 to 35 kV, repetition frequency up to 10 kHz, minimum pulsewidth 250 ns. Various types of plasma discharges, including air microdischarge for local treatments, plate-to-plate air dielectric-barrier discharge, underwater discharge, are able to be driven with good reproducibility by this compact pulse modulator. [ABSTRACT FROM AUTHOR]

Pulsed power systems often use a pulse transformer to generate high voltage pulses in some application such as radar systems, linear accelerators, and klystron modulators. Parasitic parameters include leakage inductance and capacitances are crucial for output waveform of pulse transformers. To ensure a rectangular pulse shape with a fast rise time, a required small overshoot and an acceptable voltage droop, theoretical calculation based on MATLAB is studied to optimize the design of the pulse transformer in this paper. Based on the theoretical calculation results, Finite Element Method simulations of magnetic and electric fields are carried out to obtain a more precise model for designing the transformer. Additionally, as the pulse transformer related in this paper works on the single forward state, a dc reset circuit, which can improve the utilization of the core material is implemented. Finally, accurate simulations of the pulse system equivalent circuit based on SABER are implemented. Meanwhile, output waveforms of pulse systems with different parasitic parameters and variable load are discussed. The simulation and experiment results showed that the optimum design of pulse transformer based on MATLAB programming and SABER simulation is effective to reduce the rise time of rectangular pulse shape to 1.5 \mus while the pulse duration is as large as 200 \mus. [ABSTRACT FROM PUBLISHER]

Compulsators have been considered appropriate pulsed power supplies for electromagnetic railguns. In order to ensure a high projectile mean to peak acceleration ratio, it is desirable to provide a flat-topped pulse for the railgun. This paper analyzes a two-axis-compensated compulsator, which is a refined selective passive compulsator having an orthogonal displacement between compensating winding and field winding. During the discharge process, the quadrature-axis compensation is provided by the compensating winding, when direct-axis compensation is provided by the field winding. Compared to the traditional selective passive configuration, this arrangement is able to provide another degree of freedom to compensate the armature reaction, thus an output of a current waveform with more flexibility. In this paper, the self-excitation and discharge process of a two-axis-compensated air-core compulsator is simulated based on a finite-element model. Analysis of the current waveform sensitivity to compulsator design parameters is also carried out, as well as the regulation strategy to generate a flat-topped pulse. The research process mentioned in this paper could help to optimize the design of compulsators in future applications. [ABSTRACT FROM PUBLISHER]

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits. [ABSTRACT FROM PUBLISHER]

As the most efficient and compact sources in pulsed power supply for electromagnetic launchers, the air-core pulsed alternator can supply a current as high as 1 MA with a voltage reached several kilovolts. The machine performs various functions, such as kinetic energy storage, electromechanical energy conversion, and power conditioning, making the electromagnetic launch system compact and lightweight. But due to the short history of the machine and the absence of fabrication experience in China, the air-core pulsed alternator is still in an exploratory stage, and there are lots of key technologies and problems needed to be researched deeply. Taking technical risks and manufacturing costs into consideration, a seven-phase air-core pulsed alternator has been proposed and the machine is under development. In this paper, operation principles of the electromagnetic launch system are presented in detail. The mathematical models of the seven-phase alternator and the rail gun are introduced. Based on the mathematical models, a simulation model about the electromagnetic launchers is built, and it is useful to help us figure out the operation characteristic when the self-excitation machine drives the electromagnetic rail gun with a 200-g projectile. As a result, it is convincing by simulation to prove the drive current can be as high as 1 MA and the projectile is with a velocity of 2 km/s at the exit. Simultaneously, violent transient situations will be illustrated in this text, such as the electromagnetic torque and the rotor speed. Meanwhile, simulation results can verify the analytical method and present the current and voltage straightforwardly. They also have great significance on choosing the proper high power switching devices. [ABSTRACT FROM PUBLISHER]

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit is a widely used topology in inductive pulse power supply. Therefore, it is important to understand the relationship between the STRETCH meat grinder performances and the inductor parameters when improving the system performance and designing the inductor. From the perspective of inductor designing, this paper uses four indicators to present the STRETCH meat grinder performances, i.e., the charging current, the current amplification, the inductor energy density, and the discharge efficiency, and uses two indicators to present the inductor parameters, i.e., the total inductance and the ratio of the inductance L1 to L2 . First, the meanings of the indicators are explained or defined. Second, simulations and experiments are carried out, respectively, to analyze the trends of the four performance indicators along with the changes of two parameters indicators. Finally, both simulation and experiment results show that the increase of the total inductance leads to the decrease of the charging current and the discharge efficiency; moreover, the increase of the ratio of the inductor L1 to L2 leads to the increase of the current amplification and the discharge efficiency, but causes the decrease of the inductor energy density. [ABSTRACT FROM AUTHOR]

This paper demonstrates the practical application of the explosive magnetic generator (EMG) as a source of high-power pulses for mobile testing complex EMG (MTC EMG). Hereinafter, the name of explosion generator is used on a par with the name of helical explosion-magnetic generator. Laboratory sample was brought to a level of modern complex, which is able to solve the applied problems in the grid power systems. MTC EMG is able to reproduce the output currents, similar to lightning currents, so it can be used to simulate a pulse impact on the energy system. The report contains: a description of the basic physical and electrical solutions underlying the construction of the generator of lightning currents, output characteristics, and results of MTC EMG field testing. Optimization of schemes including the different impedances of EMG and inductive resistive load with the use of transformer coupling allowed the effective energy transfer from the EMG to the load. Pulse currents and voltages on the load and also the response of soil between ground loops under the action of lightning currents, generated by MTC EMG, were registered in the testing. Autonomous measuring instruments included in the complex were protected from electromagnetic interference. [ABSTRACT FROM AUTHOR]

This paper details the experimental evaluation and simulation of a 4-kV n-type gate turn-OFF thyristor (GTO) designed for pulsed power applications. The primary criteria of evaluation are rate of current rise ( dI/dt ), turn-ON delay time ( T_{D}) , and resistance of the device during turn-ON transients [ R_{\mathrm{\scriptscriptstyle ON}}(t)$ ]. The device under test (DuT) is an n-type asymmetric-blocking GTO manufactured by Silicon Power (Part No. 14N40A10) with a rated dc blocking voltage of 4 kV. A test circuit was specifically designed to minimize stray inductance in order to capitalize on the dI/dt$ capabilities of the DuT. Experimental data collected from resistance measurements are used to develop a single-switch approximate model for use in simulation. The results of dI/dt$ experiments provide a profile of DuT dI/dt$ operation beyond rated values; specifically dI/dt were readily achieved. The turn-ON delay time of the DuT is also characterized and determined to be $\sim 225$ ns on average. [ABSTRACT FROM AUTHOR]

Multisegmented dual-stator pulsed linear induction motor (LIM) is suitable for electromagnetic (EM) catapult based on the former research. This paper mainly analyzes the numerical model of same and reverse mode of the dual stator, magnetic thrust and EM parameters, and the magnetic field distribution has been built by finite-element model and the static performance are gotten by the prototype machine. Based on the analysis results and static experiments, the closed-loop control models for the dual stator have been established, and the dynamic launch test has been performed by using of multisegment prototype LIMs. The test results show that the dual-stator LIMs can accelerate the 300-kg load to the speed of 15 m/s within 11-m launch stroke. The fluctuation of the slip frequency is quite small and the block transition is smooth during the launching process. The test results show good agreement with the commanded values, which verify the dual-stator LIM model and control strategy. [ABSTRACT FROM AUTHOR]

Great interest has been devoted to the study of nonlinear transmission lines (NLTLs) for radio-frequency generation. The two better known configurations of NLTLs are a dispersive line consisting of sections with nonlinear components and a continuous nondispersive line called gyromagnetic line. The goal of this paper is to study the gyromagnetic line through the effects of changing the NLTL parameters. This is done based on an analytical model supported by SPICE circuit simulations and validation of results with numerical analysis, focusing on the pulse rise time compression. Different models are studied by comparing simulations with corresponding results found in the literature. Such a technique could be used for the design of NLTL for space applications and mobile defense platforms of compact size. [ABSTRACT FROM AUTHOR]

The superconducting inductive pulsed-power supply (SPPS) circuit consists of a high-temperature superconducting pulsed-power transformer (HTSPPT) and an auxiliary capacitor. The electrical losses and the power of the primary source can be cut down with the superconducting inductive energy storage. Although its energy density is slightly less than a purely superconducting inductive system, it can reduce the maximum voltage of the opening switch by the capacitor and achieve a high degree of current amplification factor. However, during the discharge process, the magnetic leakage flux energy stored in the primary of the HTSPPT requires the capacitor to have a certain capacity. The higher the ratio of the capacitive stored energy over the total inductive stored energy, the more the dominant position of inductive energy storage reduces. The current amplification factor ( \gamma ), the maximum voltage of the opening switch ( V_{S\max } ), and the ratio of capacitive stored energy ( \eta ) are the three main properties of the SPPS circuit, which depends on several intertwined critical parameters, such as the inductance ratio n = L2 /( L2+LL ) and the capacitance ( $C_{{\mathbf {1}}}$ ). This paper studies the influence of the critical parameters on the main circuit performance with a 1-kJ SPPS system. The detailed selection method of the critical parameters for the specific system is also discussed with a coupling coefficient of 0.95. Such a system is easy to be utilized for the basic experimental study of a small railgun. [ABSTRACT FROM PUBLISHER]

By applying the principle of inverse current commutation with semiconductor (ICCOS) devices in a slow transfer of energy through capacitive hybrid (STRETCH) meat grinder system, a novel circuit topology called STRETCH meat grinder with ICCOS was proposed by the Tsinghua University in 2013. It can not only raise the amplitude of the opening current, but also reduce the cost of the STRETCH meat grinder circuit obviously by replacing the integrated gate-commutated thyristor (IGCT) with thyristor. This paper discusses the overall design, system implementation, and testing results of a STRETCH meat grinder with ICCOS system with roughly 1-kJ inductive energy. The load is a spiral coil with 1.4- \textm\Omega resistance and 1.4- \mu \textH inductance. With closed-loop control strategy, the system detects the charging current of the inductors. When it reaches the designated value, the triggering signal for ICCOS is delivered and after the predefined delay time, the triggering signal for discharging the voltage on the pulse-forming capacitor is delivered. The current of the inductors and the load are measured by Rogowski coils. The opening current is 1 kA and the maximum load current is close to 4 kA. All the voltages on the switches are lower than 1 kV. The experimental results are consistent with the simulated ones, which verified the correctness of the theoretical analysis and proved the applicability of the STRETCH meat grinder with ICCOS for larger energy level. [ABSTRACT FROM PUBLISHER]

Structural parameters directly affect the energy density and the total resistance of the inductors used in inductive pulse power supply (IPPS). This paper elaborates the relationship between the structural parameters and electrical performances of the inductors used in IPPS and set up the inductors for the experiment in slow transfer of energy through capacitive hybrid meat grinder circuit using air-core flat spirals of strip coil. Then we compile a program that can obtain the structural parameters of the inductors that have the highest energy density under the condition of given charging and discharging currents as well as inductances in the primary and secondary sides. The calculation results of the program are analyzed and verified by the measured values of the real inductors. At the end, on the condition of a constant current density, we put forward a rule that along with the increase in the system energy, the energy density of the IPPS became higher and the resistance of the inductors became lower. [ABSTRACT FROM PUBLISHER]

After preliminary tests using a small 25 mm-caliber electromagnetic launcher, a larger mid-caliber launcher has been designed and fabricated. The launcher has a rectangular bore of 40 mm $\times $ 50 mm, where the rails are separated by 50 mm from each other and are 5.6 m long. To deliver an electrical current to the launcher, a new 4.8-MJ pulsed power supply (PPS) consisting of eight 600-kJ segments has been constructed. The 600-kJ segment is a basic building block of PPS operated independently. It contains a controller, a charger, a safety circuit, and six 100-kJ unit modules. Each unit module in the segment is composed of a 100 kJ capacitor bank, a thyristor switch, a crowbar diode, and a pulse-forming inductor. The modules in a segment are charged to the same voltage, but they are designed to have different triggering times to make a flexible shape of current waveform. The electrical parameters of the PPS were determined through the discharges of the unit modules and those of the rails were measured by launch experiments or short circuit tests at the ends of the rails. Launch experiments have been done using several current waveforms. The current of 1 MA in a few milliseconds accelerated the armatures of several hundred grams in mass to velocities near 2 km/s. In this paper, the design and basic performance of the constructed PPS and the electromagnetic launcher are presented. [ABSTRACT FROM PUBLISHER]

The Precision High Energy-Density Liner Implosion Experiment (PHELIX) is a pulsed power driver capable of delivering multimegampere currents to cylindrical loads. The PHELIX hardware includes novel design features to provide a high-energy conversion efficiency of approximately 10-MA output current per megajoule of stored energy. This is achieved by a rail-gap switched low-inductance Marx design (resistively damped) driving a multifilar air-core pulse transformer. The Marx output cables form the toroidal transformer that is an integral part of the disc line and removable load cassette assembly. The transformer and disc line uses conformal insulation methods and does not require replacement; after each shot, the transformer is completely reusable. Load cassettes can be easily exchanged to facilitate experimental variation. PHELIX is self-contained within its own transport container and Faraday cage that can be moved from the maintenance building to the Los Alamos Neutron Science Center 800-MeV proton accelerator facility to perform multipulse proton radiography. This paper details the electrical and mechanical design of the Marx and multifilar transformer assemblies as well as presenting the operational performance achieved to date. [ABSTRACT FROM PUBLISHER]

The main characteristics of reversely switched dynistor (RSD) are infinite series, long lifetime, turning on in microseconds to nanoseconds, high-current rise rate (100 kA/\mus), and ability of passing through large current (several kiloamperes). With these advantages, RSD has a great potential of application in repetition rate pulsed power technology and the future HVdc field. To resolve the problem of residual voltage of RSD caused by insufficient precharge, which leads to nonuniform turn-on of RSD, this paper, based on the conduction mechanism of RSD devices, describes precharge circuit design requirements and establishes a second order circuit model to study the resonant triggering circuit of RSD. It is found that reducing precharge inductor can effectively increase precharge current, resulting in reducing the turn-on voltage of RSD. Finally, design for three improved circuit topologies (full-bridge, intense pulsed, and two-step triggering circuit) are presented and experiments show that these improved circuit topologies can enhance the precharge efficiency and reduce the turn-on voltage of RSD. [ABSTRACT FROM PUBLISHER]

SPHINX is a microsecond linear transformer driver located at Atomic Energy Comission (CEA) Gramat (France), which can deliver a current pulse of 6 MA within 800 ns in a Z -pinch load. Using the concept of the dynamic load current multiplier (DLCM), which was proposed by Chuvatin, we expect to increase the load current above 6 MA, while decreasing its rise time to \sim300 ns. The DLCM developed by the CEA Gramat and International Technologies for High Pulsed Power (ITHPP) is a compact system made up of concentric electrodes (autotransformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-hole rods), and a closing switch (compact vacuum surface switch). The latter is a key component of the system, which is used to prevent the current from flowing into the load until the inductance builds up due to the implosion of the wire array. This paper presents the design and testing of the DLCM surface switch, resulting from both electrostatic simulations and experiments on the SPHINX generator. These studies, carried out either with or without load (open circuit), were valuable for a first experimental evaluation of the DLCM scheme in a microsecond regime and provided detailed information on the surface switch behavior. [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]