Repetitive Pulsed Power Based on Semiconductor Switching Devices

Review on application of double-discharge circuits with inductive energy storage (IES) and semiconductor opening switch (SOS) for development of efficient gas lasers is presented. It was shown that the IES allows to form long-lived stable discharge in different gas mixtures. As a result, pulse duration, output energy and efficiency of the lasers under study were improved.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

On the base of novel circuitry approach a SOS-based (Semiconductor Opening Switch) all-solid-state repetitive generator has been developed for various technological and industrial applications. The generator is equipped with a circuit for recuperation of unused energy reflected back from the magnetic compressor. The SOS is pumped in a novel pumping regime that includes microsecond forward pumping and current pause before fast reverse pumping process. As a result, the total efficiency of the generator has been increased from usual value of around 40% up to 60-62%. The generator has the following output specifications: peak voltage is up to 60 kV; peak current is up to 6 kA; FWHM is around 40 to 50 ns; pulse repetition frequency in continuous mode is up to 1 kHz; output average power in matched load is up to 9 kW. Electrical circuit diagrams and principle of the generator operation as well as experimental and testing results obtained are described. The results of numerical simulation of the SOS diode operation are presented also.

Forward pumping current is required for current interruption operation of a semiconductor opening switch (SOS). In this study, the influence of the forward pumping current on current interruption of the reverse current has been investigated experimentally. The duration and the peak value of the forward current were varied and the reverse current obtained under different conditions has been compared. As a result, it has been found that a short forward current can lead to high peak value of the reverse current. It is considered from the results that the density of the minority carriers is increased by the forward current of shorter duration because recombination consumes fewer carriers. Furthermore, when the duration of the forward current shortens with a lower peak value and depletion the peak value of the reverse current increases, the interruption of reverse current quickens. This can be explained by the fact that the time during which minority carriers are turned around by the reverse current is shorter in case of less accumulation and faster removal of minority carriers. With these investigations, it has been understood that relatively short and low forward current and high reverse current is needed for high efficiency inductive energy storage circuit using the SOS.

Influence of streamer-to-glow transition in NOx removal from a simulated diesel exhaust gas using pulse streamer discharge (PSD) reactor is described in this paper. A co-axial cylinder type discharge chamber was used as the PSD reactor which was driven by inductive energy storage (IES) pulse power generator with semiconductor opening switch (SOS). The pulsed power generator supplies both polarity of 30 kV pulse with 300 pps repetition rate and 25 ns pulse width. The co-axial cylinder plasma reactor consists of 1 mm diameter tungsten wire and 19 mm i.d. copper tube with 30 cm length. NO removal from the simulated gas (N2:O2=9:1, Initial NO concentration=200 ppm) increased with input energy into plasma reactor. The energy efficiency for NO removal was obtained to be 25 g/kWh at 30 % removal in gas flow rate of 2 L/min. However, the energy efficiency decreased to 4.6 g/kWh with increasing capacitance of the primary capacitor from several hundreds pF to several nF. This decrease is caused with streamer-to-glow transition.

Characteristics of a newly developed static induction thyristor (SIThy) are described. The SIThy is irradiated by 2-MeV protons to improve the switching speed as a result of local carrier lifetime control. The characteristics of the proton irradiated SIThy are controlled by annealing conditions to obtain devices for various applications. The switching speed of the SIThy is very high; for example, at an anode current of 50 A, its rise time, storage time, and fall time are 100 ns, 60 ns, and 50 ns, respectively. Thus the newly developed SIThy is suitable for high-speed switching devices.

The parameters of laser radiation and kinetic processes of plasma formation and production of inverse population are studied. Electrophysical processes proceeding in a feed circuit containing a semiconductor opening switch and intermediate inductive energy storage are also considered. It is shown that the semiconductor opening switch controls the amount of energy in the inductive storage, and a high-voltage short prepulse with a peak pump power density of ∼1 MW cm-3 appearing during the current interruption can produce a volume-discharge plasma and create the inverse population for the time ∼10 ns, providing the conditions for efficient pumping of the active medium from the main capacitor. The time dependences of the pump and emission powers, the concentrations of electrons, excited xenon atoms, HCl(v) molecules in excited vibrational states and of the ionisation, recombination, and attachment rates are calculated. Kinetic processes determining the parameters of laser radiation are analysed. The output energy up to 1.0 J is obtained for 90-ns (FWHM) pulses with the efficiency up to 4.0% with respect to the pump energy. The maximum output power was 11 MW for the lasing efficiency of 4.7% with respect to the pump power. The calculated and experimental time dependences of the voltage across the laser gap, discharge current, and output power are in good agreement.

Semiconductor opening switches (SOS) are able to interrupt currents at density levels of up to 10 kA/cm 2 in less than 10 ns, operate at repetition rates up to 1 kHz, and possess lifetimes of more than 10 1 1 pulses. If stacked, SOS diodes can hold off voltage levels above a few 100 kV. They are therefore ideal for the design of compact high voltage pulse generators of the GW-class for industrial applications. The aim of this work was to improve our understanding of the opening process in a semiconductor diode of SOS-type with a doping profile of p + pnn + structure, obtainable through diffusion from the surfaces. To simulate the physical processes inside this diode the code POSEOSS was developed. It contains a detailed physical model of charge carrier transport under the influence of density gradients and electric fields and considers all relevant generation and recombination processes. It possess a large degree of flexibility and is easy to apply and thus allows to carry out parameter studies to determine the influence of different physical quantities, like doping and impurity levels, on the performance of the device. Applying the code some new interesting results concerning the plasma dynamics during the opening process in the switch have been found. Especially, using realistic values for the charge carrier mobility, it was found that the opening process starts first at the n-n + boundary. Also it has been possible to derive the physical conditions for the occurrence of the SOS-effect. Based on the simulation results a simplified SOS equivalent circuit model has been developed. This model can be used in the circuit simulation program PSpice. A new pulse generator scheme based on inductive storage is proposed, in which power multiplication is achieved by unloading the inductors, previously charged in series, in parallel. This scheme can be considered as the inductive equivalent of a Marx-generator. PSpice simulations of such a scheme based on semiconductor opening switches are presented. The theoretical results were compared to measurements obtained with a simple experimental set-up using two 100 kV SOS-switches. The measurements showed good agreement with the simulation results. Further improvements seem possible by adapting the SOS device structure to the specific generator circuit.

Inductive energy storage in conjunction with opening switch techniques has many advantages over conventional, capacitive power approaches for high-energy (>10MJ), high-power (>10l2W) applications.1 The principal advantages of inductive storage derive from the 10–100 times higher energy density possible with energy stored in magnetic fields as compared with electric fields and that energy can be stored at low voltage. In theory, this makes compact and economical generators possible.2 In any inductive storage scheme, the opening switches represent the most critical elements. One such possible switch is the plasma erosion opening switch (PEOS). This switch has been proposed to be used either by itself3 or in sequence with other opening switches4 in several inductive-store, pulsed-power systems. Recently, inductive-store/ pulse-compression techniques employing the PEOS have been successfully adapted to conventional pulsed-power generators for the purpose of improving their performance, e.g., peak voltage, peak power, and pulse width.5–11 In addition to inductive store applications, the PEOS has been used extensively in high power generators for prepulse suppression, improving power flow symmetry, and current risetime sharpening.5,6,12–18 Depending on the specific application, the PEOS has demonstrated opening times less than 10 ns, conduction times approaching 100 ns, conduction currents as high as 5 MA, and voltage generation over 3 MV without breakdown. Present research is directed toward obtaining a better understanding of PEOS physics and the interaction of the PEOS with the other system components to optimize system performance.

A new repetitive pulsed-power generator "ETIGO-IV" has been developed for the applications in materials science, pulsed ion-beam acceleration, and high-power microwave generation. It is capable of delivering, to a matched load, an output pulse of 400 kV in peak voltage, 13 kA in peak current, and 120 ns in pulsed length, at the repetition rate of 1 Hz. This paper reports the design details and operation results of "ETIGO-IV", as well as the initial experimental results on electron beam production.

A new scheme of pulsed voltage adding using inductively charged Blumlein lines has been proposed and experimentally demonstrated. The circuit principle is explained based on the analogy with capacitively charged Blumlein lines. In the experiments, striplines have been used for inductive energy storage, and SiC power devices have been used as the opening switches. The experimental results have proved both the circuit behavior and the voltage adding by using multimodule stack. This circuit method is expected to become a new approach to compact and repetitive pulsed-power generation.

A new configuration of virtual cathode oscillator is proposed and tested experimentally. A resonant cavity is used to enhance the field feedback to the virtual cathode oscillation. The experiments were carried out on repetitive pulsed power generator “ETIGO-IV” (400 kV, 13 kA, 120 ns, 1 Hz). The diagnostic results have shown the peak microwave output power of ∼ 450 MW, giving peak-to-peak microwave power efficiency of ∼ 9 %.

This paper introduces recent activities on Marx-based compact repetitive pulsed power generators at the Institute of Applied Electronics (IAE), China Academy of Engineering Physics (CAEP), over the period 2010–2018. A characteristic feature of the generators described is the use of a simplified bipolar charged Marx circuit, in which the normal isolation resistors or inductors to ground are removed to make the circuit simpler. Several pulse-forming modules developed to generate a 100 ns square wave output are introduced, including thin-film dielectric lines of different structures, a pulse-forming line based on a Printed Circuit Board, and non-uniform pulse-forming networks. A compact repetitive three-electrode spark gap switch with low-jitter, high-voltage, and high-current was developed and is used in the generators. A positive and negative series resonant constant current power supply with high precision and high power is introduced. As an important part of the repetitive pulse power generator, a lower jitter pulse trigger source is introduced. Several typical high-power repetitive pulsed power generators developed at IAE are introduced including a 30 GW low-impedance Marx generator, a compact square-wave pulse generator based on Kapton-film dielectric Blumlein line, a 20 GW high pulse-energy repetitive PFN-Marx generator, and a coaxial Marx generator based on ceramic capacitors. The research of key technologies and their development status are discussed, which can provide a reference for the future development and application of miniaturization of compact and repetitive Marx generators.

One of the promising designs of high power nano and subnanosecond pulse generators is based on FID-stacks triggered with a nanosecond pulse of overvoltage. This pulse is usually formed by semiconductor opening switches (DSRDs). Delay time of these switches is equal to the sum of forward and reverse current pulse duration, i.e., several hundreds of nanoseconds. Due to special diode structure, a novel opening switch, inverse recovery diode (IRD), is capable of forming the nanosecond pulse of voltage with a delay time equal to the reverse current pulse duration (15-20 ns). The high voltage nanosecond pulse formed with the IRD is used for fast triggering of the first DC-biased FID from a high voltage DC-biased FID-stack. The formed fast overvoltage pulse is applied to the second FID, etc. As a result, the high voltage FID-stack is switched on the order of a nanosecond. The total delay time of the IRD-FID based pulse generator is less than 30 ns

A ns pulse voltage was used to drive a coaxial geometry corona reactor to synthesis ozone with high energy yield. The ns pulse voltage was produced using an inductive energy storage system pulsed power generator using semiconductor opening switch (SOS) diodes. First recovery diodes were used as SOS diodes in the inductive energy storage system pulsed power generator to produce short-pulse high voltage with high-repetition rate. The pulse voltage of 12 ns width and 17 kV peak voltage was produced at charging voltage of -5 kV and was applied to a 1 mm diameter center wire electrode in the coaxial geometry reactor. The copper cylinder of 19 mm inner diameter was used as outer electrode and was connected to a ground. The ozone yield of 230 g/kWh was obtained using ns narrow pulse voltage. This value is almost 20% higher than 190 g/kWh obtained by 60 ns width pulse.

The deposition of diamond-like carbon (DLC) films at subatmospheric pressure has been achieved by the nanopulse plasma chemical vapor deposition (CVD) method. To realize this process, a high ion density and non-arcing plasma at subatmospheric pressure are required. A static induction (SI) thyristor with an inductive energy storage (IES) circuit was used. The DLC film was obtained under the conventional low-pressure process at 6 Pa, and the characteristics of the high electron temperature and the exponential relationship between pulse frequency and growth rate were observed. Deposition of the DLC film was also achieved at the subatmospheric pressure of 26.7 kPa (200 Torr) using this nanopulse plasma CVD method.