Fast Pulsed Power Research Articles

Development and switching characterization of high power pseudospark switch for fast pulsed power applications

Development and switching characterization of high power pseudospark switch for fast pulsed power applications

Sliding mode control for pulsed load power supply converters in DC shipboard microgrids

Pulsed power load (PPL) is a special load type in shipboard microgrids (SMGs), which consists of the generation module, energy storage system, and various types of loads. Having a reliable power supply to shipboard loads is a challenge as the SMG operates in islanded mode in most cases. Particularly, the PPLs require high transient power transfer with fast dynamics and strong robustness. Conventional solution to supply for the PPL is based on proportional-integral (PI) control, which can be used by linearizing the system around the equilibrium operation point. However, for a pulsed power supply (PPS) system, the load demand drastically changes in a short time, usually in millisecond level, making the operating point changes when the pulsed power is triggered or terminated. To supply the PPL with fast dynamics and robustness, an improved PPS control method is presented in this paper. By adopting a nonlinear sliding mode control (SMC) method, fast voltage regulation and robust pulse power tracking can be achieved. In the PPS, the PPL power demand is divided into two terms: one is the average power that is supplied by the SMG and the other is the fast pulsed power that is supplied by the storage capacitor. The size and cost of the storage capacitor are reduced as it is intentionally driven to a deep discharge. The PPS system configuration and coordination principle, SMC controllers, and sizing of passive elements in the PPS are analyzed in detail. The effectiveness of the presented PPS is verified by simulation results.

Design and implementation of module fault interlock and protection system of HIAF-BRing power supply prototype

Power supply prototype in High Intensity heavy ion Accelerator Facility-Booster Ring (HIAF-BRing) adopts the scheme of full energy and fast cycle storage pulse power supply topology. Its multi modules are connected in series and parallel pattern, and the power reaches megawatt level. Due to the high power and large scale of the power supply, a module fault interlock protection system based on Programmable Logic Controller (PLC), interlock boards and Field Programmable Gate Array (FPGA) is designed and implemented to protect the power supply in operation. In this paper, first, a design of double redundant module fault interlock is introduced. Second, the logic implemented in PLC is described. Third, the work about FPGA is given. Finally, the system is tested in three aspects: the responsive time of the power supply interlock loop, the total time from controller error occurrence to interlock finish, and the equipment fault response. The result shows that the module fault interlock system can action sensitively, timely and reliably in case of fault occurrence, which meets the requirements of the power supply prototype in HIAF-BRing.

Effect of Nitrogen Gas Plasma Generated by a Fast-Pulsed Power Supply Using a Static Induction Thyristor on Scrapie Prion.

Previous studies show that nitrogen gas plasma generated by a fast-pulsed power supply using a static induction thyristor has both virucidal and bactericidal effects. In this study, nitrogen gas plasma was further evaluated for its potential effects on prions, which are well known to be the most resistant pathogen to both chemical and physical inactivation. Aliquots (10 μL) of mouse brain homogenate infected with Chandler scrapie prion were spotted onto cover glasses and subjected to nitrogen gas plasma. Treated samples were recovered and subjected to further analyses. Control prion samples were prepared in exactly the same way but without plasma treatment. Protein misfolding cyclic amplification (PMCA) showed that nitrogen gas plasma treatment at 1.5 kilo pulse per second for 15 or 30 min caused a reduction in the in vitro propagation level of PrPres (proteinase K-resistant prion protein), which was used as an index of abnormal prion protein (PrPSc). Moreover, mice injected with prion treated with plasma for 30 min showed longer survival than mice injected with control prion, indicating that nitrogen gas plasma treatment decreased prion infectivity. Altogether, these results suggest that nitrogen gas plasma treatment can inactivate scrapie prions by decreasing the propagation activity and infectivity of PrPSc.

Compact differential B-dot monitors for measuring current on a fast pulsed power generator

Compact differential B-dots have been mounted on a fast pulsed power generator for experimental current measurements. The fast pulsed power generator is named Thunderbird, which is capable of 130 kA in ∼25 to 35 ns rise-time. A compact design (1.0 mm diameter loops in an 8.0 mm diameter body) of the B-dots has been implemented to match the need and specifications of the Thunderbird generator. The B-dots have been calibrated using a short circuit load geometry for two conditions, an uncompressed and a compressed pulse, with a circuit model, and results are shown.

Application of fast pulsed power supply to high energy photon source

High Energy Photon Source (HEPS) is the next generation of high-brightness photon source based on storage ring planned in China. Its natural emittance of the beam is close to the diffraction limit. As a typical low emittance storage ring (LER), the dynamic aperture of HEPS is far smaller than the physical aperture. Hence the traditional off-axis cumulative injection can not meet the requirements, and only strip-line kicker based on in-line injection scheme can be used. In order to realize bunch-by-bunch control, HEPS requires injecting kicker electrical pulse with a bottom width (3%-3%) of less than 10 ns, a half width (50%-50%) of more than 4.5 ns, an amplitude of +17.5 kV (50 load) and a repetition frequency of more than 50 Hz. A prototype of bipolar fast pulsed power supply based on DSRD has been developed on the project of HEPS-TF. The performance of the prototype can produce a pulse at 50 load with rise time (10%-90%)2.6 ns, fall time (90%-10%) 3.2 ns, FWHM (50%-50%) 5 ns, bottom width (3%-3%) 10 ns, amplitude 18 kV. It can meet the requirement of on-axis swap-out injection which is the baseline injection scheme of HEPS.

Basic dynamic and scale study of quasi-spherical Z-pinch implosion

Unlike cylindrical Z pinch, a quasi-spherical implosion enables load plasma to implode inward spherically and concentrate its kinetic energy toward the center. This helps to improve the energy-transport efficiency and increase the shock-induced radiation intensity of the foam convertor, when the quasi-spherical implosion is used to drive a dynamic hohlraum (DH). In previous work, it has been proved that a spherical metal shell with an exact mass-distribution can implode spherically by the nonuniform magnetic field, whose magnitude increases with the load latitude, Bφ~cos-1θ. However, this ‘mass-redistribution’ method is hard to realize on the fast pulse power generator widely used in today's Z-pinch study. The rise time of the facility is only ~100 ns, and the load is wire arrays with typical weight about 1 mg/cm. We develop a method of gaining quasi-spherical implosion with wire arrays by adjusting their initial shape, and it proves feasible on the 1.5 MA Qiangguang-I facility. Recently, we try to realize the quasi-spherical dynamic hohlraum (QSDH) implosion on generator with higher current, such as the 4.5 MA Angara5-I or the 8 MA PTS facility, and to make a direct compare with its cylindrical equivalence. But first of all, a basic but relatively comprehensive study on the quasi-spherical implosion dynamics is necessary and useful for the future QSDH load design and optimization.#br#Comparing with the device for classical cylindrical Z-pinch implosions, the load and electrodes structures of quasi-spherical implosions are complex, which leads to distinct implosion dynamics and scale rules. In this paper, we develop a thin shell model for the quasi-spherical implosion, from which the movement equation, as well as the energy scale relation is derived analytically. It is found that under the same drive condition, the implosion velocity and total kinetic energy of cylindrical load are higher than those of quasi-spherical one. However, as we expected, the quasi-spherical implosion has larger kinetic energy density, which is important for the applications such as driving a dynamic holhraum. Besides the peak current, the kinetic energy of quasi-spherical implosion also depends on the initial size of the load. By increasing the initial radius and maximum latitude angle moderately, one can obtain higher kinetic energy and energy density of the implosion, which is crucial for the load design. The theoretical study is supported by simulation results. It is found that under a drive condition close to that of the ZR facility, a quasi-spherical load with an initial radius of 5 cm will reach a peak kinetic energy density of 3.2 MJ/cm, which is about 3 times those from the cylindrical ones.

Dynamic Characteristics of X-pinch Experiments Conducted in a Small Capacitive Generator:Refractive Optical Observations.

Among the dense plasmas configurations of interest for applications as a portable intense source of X-rays, the X-pinches are the most attractive by their brightness, source size, short duration and space localization, being particularly reproducible when they are conducted with fast pulsed power generators. In recent time, several characteristics of the dynamics and emission have been reproduced in compact generators (typically capacitive generators) of low current rise-rate (less than 0.5 kA/ns). In this work, a preliminary characterization of the dynamic of X-pinch plasma conducted in a small capacitive generator is reported. In order to obtain the plasma dynamics and quantitative information of the plasma density, the dark field Schlieren technique and interferometry were implemented. The experiments were carried out on the multipurpose generator (1.2 μF, 345 J, 47.5 nH, T/4=375 ns and Z = 0.2 Ω in short circuit) capable to produce currents up to 122 kA with 500 ns quarter period, when a charging voltage of 24 kV and metallic X-pinches are used as load. The electrical behavior of the discharge and the X-ray emission are monitored with a Rogowski coil and filtered PIN diodes respectively. For the refractive optical diagnostics a 532 nm frequency- doubled Nd-YAG laser was used. As from a single Schlieren record per shot, a sequence with the time evolution of the plasma is constructed. From the images, a similar dynamic of X- pinches conducted in fast generators of high current is observed, where structures such as coronal plasma, plasma flares and plasma jets are identified. The plasma dynamics observed from a VUV gated pinhole image system is compared with registered dynamic with refractive optical techniques.

Simulation and solving the descriptive equations on the voltage breakdown in ultra-quick circuit breakers

This paper presents descriptive equations on the voltage breakdown in ultra-quick circuit breakers (UQCB). In this paper, main breakdown characteristics of UQCB\'s are presented. Gaseous breakdown in the sub-nanosecond regime is of interest for fast pulsed power switching, short pulse electromagnetics, and for plasma limiters to protect devices from high power microwave radiation. In order to study pulsed gas breakdown initiation dynamics, a sub-nanosecond voltage pulse is simulated by Electro-Magnetic Transient Program (EMTP). Keywords: Ultra Quick circuit breakers, Voltage breakdown, Gaseous breakdown, Transient recovery voltage.

The Design of Fast Pulse Power Generator with Low Voltage

In recent years, nanosecond pulse power techniques used in the millimeter-wave solid-state pulse power amplifiers attracted much attention. The rise- and fall-time of the pulse, the flatness of pulse-top and the stability of pulse-to-pulse, which have play important roles in a nanosecond pulse power generator techniques, and directly determine the system performance. In this paper, a method using the outbreak current with low-voltage to drive MOS-FETs is proposed. The measured results show that the rise- and fall-time of the output pulse is less than 1.5 ns with a pure resistance 0.5Ω, and it only needs two 12V power supply to give a output current of 20A with a pulse width of 160 ns at a repetition rate of 540 kHz in continuous mode. A flatness of 3% for the output voltage was obtained,which meet the requirements of ka-band solid-state millimeter-wave pulse power amplifier.

Development of a 3 ns rise and fall time strip-line kicker for the International Linear Collider

The kicker systems for the damping rings (DR) of the International Linear Collider (ILC) assume the use of multiple units of strip-line electrodes and fast pulse power supplies for beam injection and extraction. The design of the DR with a 6.7 km circumference requires the kicker system to have a 3 ns (or 6 ns) rise and fall time and a 6 MHz (or 3 MHz) repetition rate. The development of a single unit of a kicker system having such a performance was carried out at KEK-ATF DR. A system to improve the rise and fall time of the kick field by combining two opposite-sign pulses was developed. A rise time for the kick field of less than 3 ns is achieved using this technique.

Magnetic Fields for the Laboratory Simulation of Astrophysical Objects

Strong magnetic fields were generated using a fast pulsed power generator, to investigate the interaction of plasma flows with magnetic fields and magnetized background plasmas. The inductive loads used in these experiments were designed using a filament and a finite element modeling approaches. Magnetic fields up to 2 MG (200 T) were measured by using the Faraday rotation technique.

High velocity flyer plate launch capability on the sandia Z accelerator

Abstract A method has been developed for launching plates useful for equation of state (EOS) studies to high velocities using fast pulsed power on the Sandia National Laboratories Z Accelerator. The technique employs magnetic pressure developed in an insulating gap between the anode and cathode of the machine to provide smoothly increasing, quasi-isentropic loading to plates of 9 – 12 mm in diameter and hundreds of microns thickness. Successful launches of titanium to ∼12km/s, aluminum to ∼13km/s, and copper to ∼10km/s have been demonstrated. The plates were monitored through the entire launch process with both conventional and spatially resolved velocity interferometry to obtain acceleration histories and impact profiles. Impacts of the flyers into aluminum wedges were also performed to experimentally estimate final plate thickness. Initial indications are that the plates are intact, slightly bowed, and at essentially ambient state.

Gas breakdown in the subnanosecond regime with voltages below 15 kV

Gaseous breakdown in the subnanosecond regime is of interest for fast pulsed power switching, short pulse electromagnetics, and for plasma limiters to protect electronic devices from high power microwave radiation. Previous investigations of subnanosecond breakdown were mainly limited to high-pressure gases or liquids, with voltages in excess of 100 kV. In this paper, we investigate subnanosecond breakdown at applied voltages below 7.5 kV in point-plane geometries in argon, with a needle radius <0.5 /spl mu/m. The coaxial setup allows current and voltage measurements with temporal resolutions down to 80 ps. Voltages of 7.5 kV (which are doubled at the open gap before breakdown) produce breakdowns with a delay of about 1 ns. With negative pulses applied to the tip and the same amplitude, breakdown is always observed during the rising part of the pulse, with breakdown delay times below 800 ps, at pressures between 10/sup 2/ and 10/sup 4/ Pa. At lower pressure, a longer delay time (8 ns at 6 Pa) is observed. We expect the breakdown mechanism to be dominated by electron field emission, but still influenced by gaseous amplification.

High velocity flyer plate launch capability on the Sandia Z accelerator

A method has been developed for launching plates useful for equation of state (EOS) studies to high velocities using fast pulsed power on the Sandia National Laboratories Z Accelerator. The technique employs magnetic pressure developed in an insulating gap between the anode and cathode of the machine to provide smoothly increasing, quasi-isentropic loading to plates of 9 – 12 mm in diameter and hundreds of microns thickness. Successful launches of titanium to ∼12km/s, aluminum to ∼13km/s, and copper to ∼10km/s have been demonstrated. The plates were monitored through the entire launch process with both conventional and spatially resolved velocity interferometry to obtain acceleration histories and impact profiles. Impacts of the flyers into aluminum wedges were also performed to experimentally estimate final plate thickness. Initial indications are that the plates are intact, slightly bowed, and at essentially ambient state.

Optical Investigation of Fast Pulsed Discharge on Surface of Ceramics for Environmental Applications

Pulsed surface discharge on the surface of ceramics was investigated experimentally. The photon counting method was applied to clarify the preceding phase of the discharge. The results indicated the effect of charge injection from electrodes. A pulsed surface discharge reactor for decomposition of nitrogen oxides utilizing honeycomb ceramics was proposed. Discharge processes were observed by framing and streak photographs taken by image converter cameras. The emission spectra from the discharge were investigated using a spectrometer. Uniform surface discharges on honeycomb ceramics were successfully obtained utilizing a fast pulsed power generator with a SI-thyristor.

Fast high-voltage pulse generation using nonlinear capacitors

Many pulsed power applications require short high-voltage pulses with a high-repetition rate. Conventional high-voltage discharge pulse-switches such as thyratrons, spark gap switches, and vacuum tube switches have a short lifetime, whereas the semiconductor switches have a long lifetime and high reliability. The semiconductor switches, however cannot be directly applied to fast high-voltage pulsed power generation due to their limited operating voltage ratings despite their relatively long switching times. Therefore, they are used with voltage amplification and a pulse compression stage. This paper describes two pulse generators that use the semi-conductor switches and nonlinear capacitors: one is based on an opening switch (IGBT) and inductive energy storage, the other is a combination of a closing switch (RSD) and capacitive energy storage.

A fast pulsed power source applied to treatment of conducting liquids and air

Two pilot pulsed power sources were developed for fundamental investigations and industrial demonstrations of treatment of conducting liquids. The developed heavy-duty power sources have an output voltage of 100 kV (rise time 10 ns, pulse duration 150 ns, pulse repetition rate maximum 1000 pps). A pulse energy of 0.5-3 J/pulse and an average pulse power of 1.5 kW have been achieved with an efficiency of about 80%. In addition, adequate electromagnetic compatibility is achieved between the high-voltage pulse sources and the surrounding equipment. Various applications, such as the use of pulsed electric fields (PEFs) or pulsed corona discharges for inactivation of microorganisms in liquids or air, have been tested in the laboratory. For PEF treatment, homogeneous electric fields in the liquid of up to 70 kV/cm at a pulse repetition rate of 10-400 pps could be achieved. The inactivation is found to be 85 kJ/L per log reduction for Pseudomonas fluorescens and 500 kJ/L per log reduction for spores of Bacillus cereus. Corona directly applied to the liquid is found to be more efficient than PEF. With direct corona we achieve 25 kJ/L per log reduction for both Gram positive and Gram negative bacteria. For air disinfection using our corona pulse source, the measured efficiencies are excellent: 2 J/L per log reduction.

Correlation between Soft X-Ray Emission and Dynamics of Fast Capillary Discharges

A capillary discharge was driven by a fast pulse power generator `LIMAY-I' (3 Ω–70 ns) to investigate plasma dynamics. A two-stage pre-ionization circuit was developed to obtain uniformly preionized plasma load as the initial condition. Time-resolved radiations from the plasma column were observed by X-ray detectors and a fast streak camera. Experimental results indicated that the column can implode (rapidly contract) stably in an initial pressure range of 200–1000 Pa of argon. The reproducibility of the signal was quite good and the behavior of plasma column was well explained by one-dimensional magnetro-hydrodynamic (1D-MHD) simulation. These results suggest that the final plasma parameters satisfy the lasing condition for collisionally pumped Ne-like Ar with a sufficient margin of stability.

Development of kA-Class ac superconducting wires

We have developed large-current-carrying superconducting wires for the application of superconductivity for fast pulsed magnets and ac power devices such as SMES, superconducting rotating machines and transformers. Critical current and ac losses measurements under 50 Hz operation have been performed. Results show that the superconducting wires have ac transport current more than 1000 A rms at 50 Hz with 2 T dc backup magnetic field, and relatively low ac losses. The result also shows that the mechanical rigidity should be carefully concerned togetther with the reduction of the losses in the development of ac superconducting wires.