Compact Pulsed Power Generator Research Articles

Preliminary experimental investigation on small-aspect-ratio cylindrical solid liner implosion using compact pulsed power generator

Small-aspect-ratio cylindrical liner implosion on timescales of the order of hundreds of nanoseconds is important in the fields of high-energy-density physics, implosion dynamics, and inertial confinement fusion. This paper describes the design and development of a cylindrical liner load that has a low inductance and uniform magnetic field and its application in the CQ7 compact pulsed power generator. The dynamic response properties and implosion symmetry of liners with aspect ratios ranging from 5 to 9 are investigated. The experimental results show that the azimuthal symmetry of the liner remains intact, and that a liner with an inner diameter of 6.2 mm and a thickness of 0.4 mm can be accelerated up to 10 km/s before the reflected beam is lost. The demonstrated high performance of the experimental technique used for imploding the liner could be beneficial for studying the implosion and dynamics of materials on compact pulse power generators in the future.

A compact platform for the investigation of material dynamics in quasi-isentropic compression to\u2009~\u200919 GPa

This paper reports on the development of a magnetically driven high-velocity implosion experiment conducted on the CQ-3 facility, a compact pulsed power generator with a load current of 2.1 MA. The current generates a high Lorentz force between inner and outer liners made from 2024 aluminum. Equally positioned photonic Doppler velocimetry probes record the liner velocities. In experiment CQ3-Shot137, the inner liner imploded with a radial converging velocity of 6.57 km/s while the outer liner expanded at a much lower velocity. One-dimensional magneto-hydrodynamics simulation with proper material models provided curves of velocity versus time that agree well with the experimental measurements. Simulation then shows that the inner liner underwent a shock-less compression to approximately 19 GPa and reached an off-Hugoniot high-pressure state. According to the scaling law that the maximum loading pressure is proportional to the square of the load current amplitude, the results demonstrate that such a compact capacitor bank as CQ-3 has the potential to generate pressure as high as 100 GPa within the inner liner in such an implosion experiment. It is emphasized that the technique described in this paper can be easily replicated at low cost.

Kinetics of Zr under shock-ramp compression

<p indent=0mm>The dynamics of Zr under shock-ramp wave loading was studied with experiments and simulations. The shock-ramp wave compression experiments of Zr with different loading thermodynamics path were carried out with photonic Doppler velocimetry (PDV) and compact pulsed power generator CQ-4. The velocity wave profiles show that Zr undergoes shock and then ramp wave compression in the loading section. When the shock pressure reaches about <sc>10 GPa,</sc> the velocity profile contains phase transition information. However, the phase transition information could not be observed when the shock pressure is up to <sc>25 GPa.</sc> It is a single shock wave when the shock pressure is at <sc>44 GPa.</sc> The experimental results are simulated with the Hayes multi-phase equation of state and the non-equilibrium phase transition kinetic model, which can well describe the physical processes of the elastoplastic transition and the phase transition in the loading section.

Compact microsecond pulsed power generator driven by solar energy for dielectric barrier discharge applications

The dielectric barrier discharge (DBD) driven by a pulsed power supply can produce non-equilibrium plasma at atmospheric pressure with merits of more uniform and higher chemical reactivity which makes it promising in various applications. To fulfil the demand of the improvement of energy efficiency and environmental protection, the power generators driven by renewable sources of energy have drawn much attention. This paper describes a microsecond pulse power generator in a compact form (300 mm×200 mm×150 mm) and driven by solar energy is built in a modular structure with solar panels, DC-DC converter, voltage stabilizer, switching system, and high-voltage pulse shaping system. The pulsed power supply has the capability of providing a high voltage pulse up to 20 kV, a pulse repetitive frequency from 1 Hz to 2 kHz, and a maximum output power of 150 W. Tests with a non-inductive resistive load and a coaxial DBD load show that the compact microsecond pulse power generator can provide positive and negative pulses, adjustable voltage amplitude, and reproducible pulse waveforms with different pulse repetition rate. Also, the pulsed power supply has the capability to excite the DBD in working conditions with adjustable output parameters.

Recent advances in compact repetitive high-power Marx generators

AbstractThis 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.

Yield behavior of polystyrene at strain rate 106/s under quasi-isentropic compression

The yield behaviors of polystyrene(PS) were researched by means of the technique of magnetically driven quasi-isentropic compression on compact pulsed power generator CQ-4 for its better applications in protection structure designs and plastic bonded explosives. The experimental wave profiles of PS under quasi-isentropic compression exhibit obvious inflection point at the interface velocity of 50 m/s between PS and LiF window, from which the isentropic elastic limit is inferred to be 0.39 GPa at strain rate of 1 × 106/s and strain of 0.06. Based on Von Mises or Tresca yield criterion under one-dimensional strain, the initial yield strength of PS is derived to be 0.186 GPa, about 4 times the value of 0.04 GPa under quasi-static compression. The hydrodynamic simulations were conducted to describe the dynamic response of PS including the Mie–Grüneisen equation of state (EOS) and Steinberg–Guinan strength model. The yield response of PS under quasi-isentropic compression can be described well in our simulations, which shows excellent agreement with the experimental data.

Phase transformation kinetics of zirconium under ramp wave loading with different windows

The effect of window acoustic impedance on the wave profile of phase transition of zirconium under ramp wave compression is investigated in experiment and simulation. In the experiments, a ramp wave driven by magnetic pressure is applied to the zirconium samples backed windows with different acoustic impedances such as LiF, sapphire and free surface based on the compact pulsed power generator CQ-4. The experimental wave profiles measured by an advanced laser interference velocimeter show that the characteristic particle velocity of the onset phase transition from to is about 331.0 m/s in the conditions of LiF widow and free surface with low acoustic impedance, and it is approximately 301.9 m/s for the sapphire window with higher acoustic impedance. The corresponding onset pressure of phase transition varies from about 9.14 GPa to 8.27 GPa. The result shows that this onset pressure of phase transition, which is affected by diverse factors, is not the inherent value of phase transition belonging to the material properties. In order to describe these dynamic responses in experiment well, the numerical simulation of phase transition dynamics of zirconium is conducted in one-dimensional hydrodynamic code, in which included are the muti-phase equation of state based on Helmholtz free energy, the equation of non-equilibrium phase transition dynamics, and Steinberg constitutive relationship. The simulated results show that they can reflect the physical processes of elasto-plastic transition and - phase transition as well, which are excellently consistent with the experimental data. The relaxation times of - phase transition in three different acoustic impedance experiments are nearly the same (30 ns), and their finishing times of phase transition are all about 100 ns. The calculated quasi-isentrope of zirconium below 20 GPa in the pressure-volume and temperature-pressure thermodynamic planes shows that the isentrope and shock adiabat exhibit tiny difference before phase transition, and then separate gradually with the increase of pressure. The isentrope lies below the shock adiabat after the onset of phase transition. At about 20 GPa, the temperature of zirconium under ramp wave loading is bout 100 K lower than that under shock loading. Meanwhile, the abrupt change of volume at phase transition causes the Lagrange sound speed to reduce about 7% and then comes back to the bulk sound speed again after the phase transition has been finished.

Characterizations of dynamic material properties on compact pulsed power generator CQ-4

Over last two decades, the techniques of magnetically driven quasi-isentropic compression and launching high velocity flyer plates based on pulsed high current generators have being extensively used to do dynamic material experiments under extreme conditions, such as high pressure, high temperature and high strain rate. A compact pulsed power generator CQ-4 was developed to do quasi-isentropic compression experiments of materials at Institute of Fluid Physics of CAEP, which can deliver maximum peak current of about 4 MA to short-circuit loads and produce approximate 100 GPa pressure on the metallic samples. On CQ-4, several types of dynamic material experiments have being conducted for equation of states, phase transitions, constitutive relationships, micro-structure evolutions of matter under quasi-isentropic compression and shock loadings. Meanwhile the dynamic behaviors of solid plastic bonded explosives and their components have also being researched for better understanding the interaction of explosive components under stress waves and the hot spot originations and evolutions mechanism of PBX explosives under dynamic loadings. Several typical applications in dynamic material properties were shown in this paper to exhibit the capabilities of CQ-4.

Verification of conventional equations of state for tantalum under quasi-isentropic compression

Shock Hugoniot data have been widely used to calibrate analytic equations of state (EOSs) of condensed matter at high pressures. However, the suitability of particular analytic EOSs under off-Hugoniot states has not been sufficiently verified using experimental data. We have conducted quasi-isentropic compression experiments (ICEs) of tantalum using the compact pulsed power generator CQ-4, and explored the relation of longitudinal stress versus volume of tantalum under quasi-isentropic compression using backward integration and characteristic inverse methods. By subtracting the deviatoric stress and additional pressure caused by irreversible plastic dissipation, the isentropic pressure can be extracted from the longitudinal stress. Several theoretical isentropes are deduced from analytic EOSs and compared with ICE results to validate the suitability of these analytic EOSs in isentropic compression states. The comparisons show that the Gruneisen EOS with Gruneisen Gamma proportional to volume is accurate, regardless whether the Hugoniot or isentrope is used as the reference line. The Vinet EOS yields better accuracy in isentropic compression states. Theoretical isentropes derived from Tillotson, PUFF, and Birch-Murnaghan EOSs well agree with the experimental isentrope in the range of 0–100 GPa, but deviate gradually with pressure increasing further.

Effect of Electrical Stimulation on Fruit Body Formation in Cultivating Mushrooms.

The effect of high-voltage electrical stimulation on fruit body formation in cultivating mushrooms was evaluated using a compact pulsed power generator designed and based on an inductive energy storage system. An output voltage from 50 to 130 kV with a 100 ns pulse width was used as the electrical stimulation to determine the optimum amplitude. The pulsed high voltage was applied to a sawdust-based substrate of Lyophyllum decastes and natural logs hosting Lentinula edodes, Pholiota nameko, and Naematoloma sublateritium. The experimental results showed that the fruit body formation of mushrooms increased 1.3–2.0 times in terms of the total weight. The accumulated yield of Lentinula edodes for four cultivation seasons was improved from 160 to 320 g by applying voltages of 50 or 100 kV. However, the yield was decreased from 320 to 240 g upon increasing the applied voltage from 100 to 130 kV. The yield of the other types of mushrooms showed tendencies similar to those of Lentinula edodes when voltage was applied. An optimal voltage was confirmed for efficient fruit body induction. The hypha activity was evaluated by the amount of hydrophobin release, which was mainly observed before the fruit body formation. The hydrophobin release decreased for three hours after stimulation. However, the hydrophobin release from the vegetative hyphae increased 2.3 times one day after the stimulation.

Compact Rep-Rate GW Pulsed Generator Based on Forming Line With Built-In High-Coupling Transformer

In this paper, a compact rep-rate GW pulsed power generator is developed. First, its three key subsystems are theoretically analyzed, engineering designed, and experimentally investigated, respectively. The emphases are put on these four problems: the theoretical analysis of the voltage distribution across the conical secondary windings of the high-coupling transformer, the investigation of the high energy storage density dielectric used in the pulse forming line, the choice of the gas flow velocity of the gas blowing system, and theoretical analysis of the passive stability of the pulsed power generator operated in rep-rate mode. Second, the developed pulsed power generator is described in detail. It has a 0.2-m diameter, a 1.0-m length, and a 20- Ω wave impedance. Across a 100- Ω resistive dummy load, it can steadily operate at a 300-kV output voltage in 50-Hz rep-rate and 250 kV in 150 Hz without gas blowing system. The average power is ~ 1 kW. Finally, the pulsed power generator is applied to drive a relativistic backward-wave oscillator, generating a high-power microwave with peak output power of 200 MW and duration (full-width at half-maximum) of 5 ns in 150-Hz rep-rate. These efforts set a good foundation for the development of a compact rep-rate pulsed power generator and show a promising application for the future.

Development of Compact Pulsed Power Generator for Improvement of Mushroom Yield

Compact pulsed power generator was developed to improve a mushroom yield and was evaluated in effect on the yield. To reduce the high-voltage generator size, Cockcroft-Walton circuit was employed. The pulsed power generator consisted of rechargeable dry cells, control unit, transformer, Cockcroft-Walton circuit, 2 m-length coaxial cable and gap switch. The maximum output voltage of the generator was 100 kV with several microseconds in pulse width. The weight of the generator was several kg which was capable of carrying the generator on farmer's shoulder.

Determining thermodynamic parameters of aluminum X-pinch plasma

Experiments on a compact pulsed power generator with an amplitude of 200 kA and a 180-ns front width loaded on an X-pinch consisting of four aluminum wires with a diameter of 35 μm have been carried out. Experimental data and the results of calculations performed in the framework of an impact-radiation model have been used to determine parameters (temperature, density, linear mass) of the X-pinch hot spot at the moment of maximum compression. It is established that (i) a pulse of soft X-ray emission from the X-pinch is generated upon almost complete ejection of substance from the hot spot and (ii) hot-spot formation in the X-pinch proceeds under conditions close to the Bennett equilibrium.

MOUNA: An Autonomous, Compact, High-Power, and Wideband Electromagnetic Source Based on a Novel Resonant Pulsed Transformer

Nowadays, a broad range of modern defense applications requires compact pulsed power generators to produce high-power electromagnetic waves. In a conventional design, such generators consist of a primary energy source and an antenna, separated by a power-amplification system, such as a Marx generator or a Tesla transformer, which forwards the energy from the source to the antenna. The present system, however, uses a novel and very compact high-voltage resonant pulsed transformer to drive a dipole antenna. The complete pulsed power source, termed MOUNA (French acronym for “Module Oscillant Utilisant une Nouvelle Architecture”), is composed of a set of batteries, a dc/dc converter for charging four capacitors, four synchronized spark gap switches, a resonant pulsed transformer that can generate 555 kV/265 ns pulses, an oil peaking switch and, during preliminary testing, a dipole antenna. The paper not only provides design details for each system component, but also presents the mechanical arrangement of the complete pulsed power system and the electrical diagnostics, particularly those related to measurement of the resonant transformer output waveform, the line oscillations, and the radiated electric field.

紧凑型X箍缩脉冲功率发生器

紧凑型X箍缩脉冲功率发生器

A compact repetitive nanosecond pulsed power generator based on transmission line transformer

In this paper, a compact repetitive nanosecond pulsed power generator based on transmission line transformer (TLT) is developed for non-thermal plasma generation. The high voltage capacitor, the spark gap switch and the input side of the TLT are built into a compact structure to obtain a fast high-power pulse. The properly designed magnetic cores placed around the coaxial cables of the TLT have been chosen to obtain a higher voltage gain. The layout of TLT is optimized to make the generator more compact. Experiment test shows that voltage pulses of 30 kV with rise time of about 25 ns, pulse duration of about 100 ns, pulse repetition rate of 500 pps have been achieved.

Design and construction of a compact portable pulsed power generator

The low impedance compact pulsed power generators are considered as potential drivers for X-pinch based phase contrast imaging and extreme ultraviolet (EUV) source for lithography. The designed pulsed power generator should provide square-like wave on low impedance load (1–2 Ω) with current amplitude of 100 kA in burst mode. The pulse width of the current wave is 60 ns, and the rise time of the wave should be less than 30 ns. The dimensions of the machine are restricted to be no larger than ∼2 × 1 × 1.5 m, according to the specific potential application of the machine. We adopted a solution based on Marx generator combined with low impedance pulse forming line and V/N type gas switch technology to obtain the required high intensity and fast rise-time current wave. Special efforts have been made to reduce the inductance of V/N switch and low impedance load section, and thus to obtain fast rise time and high peak current, during both physical and mechanical design stages. The high power transient signal diagnostic system, consisting of a capacitive voltage divider and a metal film based current monitor, and the calibration of the diagnostic system are also outlined.

Discharge characteristic of nanosecond-pulse DBD in atmospheric air using magnetic compression pulsed power generator

Dielectric barrier discharge driven by repetitive nanosecond pulses can offer highly efficient non-thermal plasma at atmospheric pressure and is widely used for plasma applications. In this paper, the discharge is generated using a compact pulsed power generator based on one-stage magnetic compression. The output pulse can be up to 30 kV with a rise time of about 40 ns and a full width at half maximum of 70 ns. The electrical characteristics of the discharge parameters are studied by the measurement of voltage and current waveforms. The effects of applied voltage amplitude, voltage polarity, pulse repetition frequency, and barrier dielectric on discharge characteristics are investigated, respectively. The experimental results show that the discharge current, discharge power and electron density increase with the increase of the applied voltage, and the pulse repetition frequency has a slight effect on the electrical parameters. Moreover, the discharge current is influenced by the dielectric barrier, but it is not varied with the polarity of applied pulses.

Agricultural and Food Processing Applications of Pulsed Power and Plasma Technologies

Agricultural and food processing applications of pulsed power and plasma technologies are described in this paper. Repetitively operated compact pulsed power generators with a moderate peak power are developed for the agricultural and the food processing applications. These applications are mainly based on biological effects and can be categorized as germination control of plants such as Basidiomycota and arabidopsis; inactivation of bacteria in soil and liquid medium of hydroponics; extraction of juice from fruits and vegetables; decontamination of air and liquid, etc. Types of pulsed power that have biological effects are caused with gas discharges, water discharges, and electromagnetic fields. The discharges yield free radicals, UV radiation, intense electric field, and shock waves. Biologically based applications of pulsed power and plasma are performed by selecting the type that gives the target objects the adequate result from among these agents or byproducts. For instance, intense electric fields form pores on the cell membrane, which is called electroporation, or influence the nuclei. This paper mainly describes the application of the pulsed power for the germination control of Basidiomycota i.e. mushroom, inactivation of fungi in the soil and the liquid medium in hydroponics, and extraction of polyphenol from skins of grape.

Elastic limit of x-cut quartz under shockless and shock wave compression: Loading rate dependence

To examine the effect of compressive loading rate on the elastic limit of brittle solids, shockless and shock wave uniaxial strain experiments were conducted on x-cut quartz to a peak stress of 11GPa. Using a compact pulsed power generator, x-cut quartz crystals were subjected to shockless compression (loading rate of ∼3×105∕s). Plate impact experiments were used to subject samples to shock wave compression (loading rate ⩾4×107∕s). Particle velocity histories, measured at propagation distances of 1.5–3.5mm, demonstrated that the elastic limit of x-cut quartz under shockless compression was 85%–90% higher than the elastic limit under shock wave compression. The substantial increase in the elastic limit with decreasing loading rate is contrary to the expected loading rate dependence of material strength. Mechanistic implications of this finding are discussed.