Showing papers on "Marx generator published in 2003"

Characterization of a high-intensity unipolar-mode pulsed ion source with improved magnetically insulated diode

Abstract: A magnetically insulated ion diode (MID) with an improved external-magnetic field system has been developed and installed onto a TEMP-6-type high-intensity pulsed ion source in order to produce a high-intensity pulsed ion beam (HIPIB) for surface modification of materials. The external-magnetic field MID is operated in unipolar mode based on dielectric high-voltage flashover, and a double coaxial pulse-forming line (PFL) powered with a Marx generator is used to form the unipolar pulse of nanosecond width. A specially designed cathode has been constructed with a forked connection to two symmetrically installed transformers to improve the effect of the magnetic field and thus increase the stability of generation and propagation of the ion beam. It was found that the efficient generation of HIPIB mainly depended on the magnetic field strength, the gas pressures in reverse and output switches of PFL, and the anode–cathode (A–K) gap of the external-magnetic field MID. A proper magnetic field strength was found with magnetic field power system at dc charging voltage of 8 kV. The proper A–K gap distance is not uniform with the value varied from 6 to 8 mm. Suitable gas pressures for reverse and output switches were about 1.2 and 2.4 atm, respectively, at a charging voltage of 40 kV to the Marx generator. The most efficient plasma generation and ion extraction led to a maximum output of HIPIB with a peak ion current density of 300 A cm−2 and a beam pulse width of 80 ns (full width at half maximum), at an accelerating pulse of 300–350 kV with a pulse width of 70 ns.

Development of an integrated solid-state generator for light inactivation of food-related pathogenic bacteria

Abstract: This paper is concerned with the design and performance of a fully integrated solid-state Marx generator, which has been developed to drive a UV flashlamp for use in microbiological inactivation. The generator has an output voltage rating of 3 kV and a peak current rating of 2 kA, although the modular approach taken allows for a number of voltage and current ratings to be achieved. The generator is constructed using a number of series- and parallel-connected 1.2 kV insulated-gate-bipolar-transistor (IGBT) switched capacitors. Switching of the IGBT modules is controlled by an optical signal. Details are given of how the optimum IGBT gate-drive circuit is achieved using optical components and a pass-through wire to provide the required energies for individual IGBT modules. The generator is demonstrated as the driver of a UV flashlamp used for inactivation of food-related pathogenic bacteria such as E. coli and Salmonella. The performance of the Marx generator over a period of 106 pulses is examined, along with the changes that occur in the spectrum of the UV flashlamp during the same period.

Compact, high power capacitor charger

Abstract: We are developing compact, high-power chargers for rapid charging of energy storage capacitors. The main application is presently rapid charging of the capacitors inside of compact Marx generators for reprated operation. Compact Marx generators produce output pulses with amplitudes above 300 kV with ns or subns rise-times. A typical application is the generation of high power microwaves. Initially all energy storage capacitors in a Marx generator are charged in parallel. During the so-called erection cycle, the capacitors are connected in series. The charging voltage in the parallel configuration is around 40-50 kV. The input voltage of our charger is in the range of several hundred volts. Rapid charging of the capacitors in the parallel configuration will enable a high pulse repetition-rate of the compact Marx generator. The high power charger uses state-of-the-art IGBTs (isolated gate bipolar transistors) in an H-bridge topology and a compact, high frequency transformer. The IGBTs and the associated controls are packaged for minimum weight and maximum power density. The packaging and device selection makes use of burst mode operation (thermal inertia) of the charger. The present charger is considerably smaller than the one presented in Giesselmann, M et al., (2001).

Development of a terawatt test stand at the University of Missouri for fast, multichannel switching analysis

Abstract: The University of Missouri Terawatt Test Stand (MUTTS) began assembly in January 2003. Construction of MUTTS is progressing rapidly with the design and development of its high energy Marx bank. The Marx bank consists of 32, 100 kV, 0.7 /spl mu/F capacitors switched by 16 Physics International T508 spark gaps. The Marx is switched into two parallel 7 nF, intermediate storage capacitors, which are fired into a dummy load through a fast multi-channeling output switch. The Marx stores 100 kJ and can deliver a voltage of 2 MV at 500 kA into a 4 /spl Omega/ load delivering 1 TW to the load. Initial testing will be of a multichanneling 2 MV output switch, which scales nicely to a 6 MV switch design for future very high energy machines at Sandia National Laboratories. The output switch is to reliably multichannel, or close with many parallel arc channels. The goal is to adapt an existing multichanneling switch to create a multichanneling output switch with significant operational advantages, including lower inductance, compared to existing multichannel switches. The target switch inductance is 100 nH or less. The facility and tank were assembled from January to June 2003, with testing to begin in July 2003. Simulations of the test stand and specifications of the output switch will be presented. Electrode configurations and switch augmentations that will facilitate a reliable multi-channeling switch will be introduced. Details describing the development of the MUTTS facility will be included.

X-ray apparatus for generating short x-ray pulses, and inspecting device operating by means of such an x-ray apparatus

Abstract: Disclosed is an x-ray apparatus for generating short x-ray pulses, comprising an x-ray tube (10) that is provided with a hot cathode (12) and a anode (16), and an x-ray generator which is provided with a first circuit (22, 20, 18) generating a high voltage pulse that is applied to the anode (16) in order to generate the x-ray pulse. The x-ray generator is provided with a second circuit (26) via which a low voltage that is not sufficient to generate x-rays (30) but preheats the x-ray tube (10) is permanently fed to the anode (16). The first circuit can comprise a high voltage power pack (22) that charges a high voltage capacitor (20) which can be applied to the anode (16) via a high voltage switch (18). The second circuit can be embodied as a Marx generator. It is possible to use a single power pack for generating the permanent low voltage and driving the Marx generator generating the high voltage. The inventive x-ray apparatus can be part of a device for inspecting objects, which comprises an imaging unit (44, 46) for creating a representation of the object by means of the x-ray (30).

ZR Marx capacitor vendor evaluation results and procurement strategy

Abstract: To meet or exceed the 26-MA goal for ZR, the refurbished upgrade to the Z machine at Sandia National Labs, the existing Marx generator capacitors is replaced with identical size units but with twice the capacitance Before the six-month shut down and transition from Z to ZR occurs in late 2005, most of the 2500 capacitors are delivered for acceptance testing and installation We chose to undertake an ambitious vendor qualification program to reduce the risk of not meeting ZR performance goals, to encourage the pulsed- power industry to revisit the design and development of high energy discharge capacitors, and to meet the cost and delivery schedule within the ZR project plans Five manufacturers were willing to fabricate and sell Sandia samples of six capacitors each to be evaluated In addition, four more samples of modified or alternate designs were submitted for testing at the vendors' expense, giving us a total of 45 capacitors to test The 8,000-shot qualification test phase of the effort is now complete This paper summarizes how the 0279x0356x0635-m Scyllac-style 26-/spl mu/F, <30-nH, 100-kV, 35%-reversal capacitor lifetime specifications is determined, briefly describes the nominal 260-kJ test facility configuration, presents the test results of the most successful candidates, and provides procurement strategy and acceptance testing protocols that balance available resources against performance, cost, and schedule risk

Solid-state Marx bank modulator for the next linear collider

Abstract: The use of solid state switches to create high voltage pulsed power is an important shift from traditional pulsed power technologies based on vacuum devices, spark gaps, and plasma switches. During the last decade, investigators at a number of institutions, including Diversified Technologies, Inc. (DTI), have examined a wide range of practical pulsed power architectures that use solid state devices. Over the past two years, DTI has demonstrated a combination of old and new technologies in a solid state Marx bank. This configuration offers a number of advantages to the broad class of pulsed power applications requiring relatively high peak power, short pulses, and low average power.

Wear-less trigger method for Marx generators in repetitive operation

Abstract: Triggered Marx-generators running in repetitive operation play an important role for many future industrial applications replacing the traditional methods for the treatment of large mass streams. A reliable operation over a fairly long time is one prerequisite, the design of such a generator has to guarantee. For conventionally triggered spark-gaps we experienced a comparatively short component lifetime. Therefore, a new trigger method based on the superposition of an additional voltage pulse to the charging voltage in a two-electrode spark-gap configuration has been developed. The paper describes the implementation into an existing Marx- design and some preliminary experimental results.

Marx generator using pseudospark switches

Abstract: The design and preliminary operation of the major subsystems of a Marx style pulse generator using advanced pseudospark devices are presented. The bank consists of three 150 nF / 40 kV capacitors connected with three floating FS2000 type pseudospark switches. These switches can hold off 35 kV and pass up to 10 kA at repetition rates approaching 1 kHz. The expected lifetime of >200 kC and the relatively low housekeeping power of <50 W make the pseudospark switch an excellent candidate in compact Marx generator applications. Preliminary operation of the floating housekeeping units essential to the Marx generator is presented in detail.

Reflex-triode geometry of the virtual-cathode oscillator

Abstract: An eight-stage four-hundred kilovolt Marx bank, in connection with a 60 nanosecond pulse-forming line, is constructed and utilized as a pulsed source to power a planar version of the virtual cathode oscillator (vircator). Eight .1/spl mu/F capacitors, charged to 50 kV each, are switched in series by dry-air pressurized spark gaps. The energy from the bank charges a 23 ohm oil transmission line, breaking a peaking gap when the maximum voltage is reached, delivering a 60 ns-300 kV pulse to the diode. The design of the planar or reflex-triode geometry vircator is based upon claims of high efficiency by Didenko et al. A previously constructed TTU vircator includes a unique E-beam source, the brush cathode; in which a circular array of pins is used as an explosive field emission source to produce relatively high beam currents. The anode consists of a round wire mesh through which the E-beam passes, generating a dense cloud of negative charge known as a virtual cathode. This initial phase of testing is composed of basic operation of the entire system and baseline output power and efficiency measurements.

Pulsed power design for a small repetitively pulsed electron beam pumped KrF laser

Abstract: Electra is a 700 J, repetitively pulsed, electron beam pumped krypton fluoride (KrF) laser that is developing technologies to meet the inertial fusion energy (IFE) requirements for rep-rate, efficiency, durability and cost Sethian, JD et al., (2002). We have designed a pulsed power system for the preamplifier in the electra KrF laser system. This preamplifier is designed to produce 40 J of laser light in a 40 nsec pulse which will be used to provide the input to the main amplifier. The pulsed power for the front end will serve two roles. It will complete the laser system and it will serve as the demonstrator for the new advanced pulsed power topology that can meet the fusion energy requirements for durability, repetition rate, and cost. The pulsed power will first employ a gas-switched Marx, with anticipated maintenance intervals similar to that of the existing electra main amplifier Sethian, JD et al., (1999). Later the driver will be replaced (circa 2006) with a solid-state-switched Marx generator D. Weidenheimer et al., (2002). The output requirements for the pulsed power driver into counter-streaming electron beam diodes are 20/40/30 nsec (t/sub rise//flat-top/t/sub fall/), 150-175 kV, 60-80 kA per side and a 1.1 ohm nominal impedance. The pulser will operate in single-shot, burst, and continuous modes up to 5 pps, with 1 nsec (1 sigma) or less absolute timing jitter. Rather than build an individual driver for each e-beam diode as was done for the electra main amplifier Sethian, JD et al., (1999), a single pulsed power driver is coupled to the opposing electron guns via four liquid-filled transit time isolators (TTIs). These TTIs are necessarily compound (oil/water/oil) in order to balance their electrical lengths against unequal mechanical lengths. The Marx is gas-insulated and charges a 1.1-ohm water pulse forming line (pfl) in less than 100 nsec. An output magnetic switch with a saturated inductance of less than 14 nH discharges the pfl into the four parallel TTIs. A set of four (2 each side) Z-stack inverted bushings connect the TTIs to the diodes. This paper will present and discuss all major aspects of the electrical and mechanical design, as well as the anticipated performance from circuit simulations. The laser driver is scheduled to be delivered to and installed at the naval research laboratory's electra laboratory in late 2003.

Electrical modeling of mercury for optimal machine design and performance estimation

Abstract: Mercury is a new pulsed-power generator at NRL, having been transferred from FZK (Forschungszentrum Karlsruhe, Germany) where it was known as KALIFHELIA [R. J. Commisso et al., 2003; P. Hoppe et al., 2001]. Mercury is an MIVA (magnetically-insulated inductive voltage adder) designed to produce 50-ns pulses with load voltages up to 6 MV at a current of 360 kA and deliver 100-kJ of energy to the load [J. Fockler et al., 1993]. The inductive and resistive components connecting the Marx bank and the intermediate stores have been reconfigured to fit into one "machine tank" and to improve energy transfer, allowing for a reduced Marx charge voltage. A detailed circuit model was developed for Mercury based on an earlier model for KALIF-HELIA and updated to include new information and data from FZK. Circuit element values for the MIVA and the load were determined through PIC simulations. Good agreement between measured and calculated current and voltage peaks was found using the model fed by voltage signals measured upstream of the MIVA on KALIF-HELIA. Detailed modeling has shown that the original design parameters of the machine can be met at NRL.

Characteristics of hard x-ray emission from laser-induced vacuum spark discharges

Abstract: An experimental study of the characteristics of hard x-ray emission in laser-induced vacuum spark discharges has been carried out. The spark discharge is performed in a gap (10 mm) of pin electrodes using a Marx generator and a laser pulse to produce Au plasma on the tip of an anode. When spark discharge with charge voltage of 150 kV occurred simultaneously with the incidence of a laser pulse, an x-ray pulse made of a short (∼20 ns) x-ray spike pulse and a long (∼400 ns) pulse was emitted with high intensity (∼10 mR per shot). The two pulses appeared at the beginning and at the latter part of discharge. The effective photon energy was around 150 and 80 keV, respectively. The results show that the x-ray intensity strongly depends on the timing of the onset of the discharge with respect to the laser irradiation, the laser intensity, and the charge voltage. The mechanisms responsible for the x-ray emission are discussed in terms of the results observed.

Prototype of a high power compact Marx generator for microwave applications

Abstract: A compact pulsed power system is described. This system has been built to drive low impedance HPM sources (vircator, MILO). It consists of two Marx generators in parallel. Each Marx contains 13 bipolar (/spl plusmn/ 50 kV) stages of capacitors and switches placed in a tank filled with dielectric oil. This system stores 10 kJ and is capable of delivering a current up to 50 kA at 800 kV to a matched load. The rise time of the current is less than 100 ns. The Marx generators and the vacuum interface have a diameter of 0.8 m and a total length of 2 m. The voltage is monitored inside the oil tank by using a resistive divider, and the current is measured under vacuum with a Bdot probe. In this paper we present experimental results with a resistive load as well as data obtained when the obtained Marx generator is coupled to HPM tubes.

Design and performance of the Marx generator for the DARHT second axis electron injector

Abstract: The injector for the second axis of the dual-axis radiographic hydrotest facility (DARHT II) is now undergoing commissioning tests at Los Alamos national laboratory. A Marx generator develops a 3.2 MV, 2 /spl mu/s pulse that is applied to the diode through a high voltage (or Marx) dome, current stalk and high voltage insulator column. The 2 kA electron beam source is a 165-mm-diameter thermionic dispenser cathode operating near 120 kV/cm. The extracted beam enters a series of eight pulsed power-driven injector induction cells that accelerate the beam to approximately 4.5 MeV. The beam then passes through a beamhead clean-up zone (BCUZ) to "scrape off" the off-energy portion of the beam (the beam leading edge and, to a lesser extent, the beam trailing edge). A crowbar switch fired at the end of 2 /spl mu/s produces a short fall time. This paper focuses on the electrical and mechanical design and testing of the Marx generator. The Marx consists of 88 stages, each half stage of which is a +/- 50 kV type EPFN. The Marx was tested for over 8000 shots before shipment to Los Alamos and demonstrated 6 ns jitter and good reliability with only 8 prefires out of 5000 shots. At the end of December 2002, nearly 800 shots have been fired in the process of commissioning the DARHT machine. The results of both series of these tests are given in this paper.

Experimental study of repetitive Marx generator

Abstract: We present the study and results obtained with a new compact repetitive Marx generator. The issue of this work was to provide an experimental high voltage repetitive generator to investigate on recurrent switching and fast power supply. To design this generator, we consider the voltage and the energy rise-time of the power supply, the total capacitance and the output voltage of the Marx. The power supply characteristics are 6 kJ/s with 40 kV and the Marx generator has 13 stages of 5.2 nF. The non-triggered gas switches work with a pressure of 3 atm. dry air/SF6 mixture and can operate at a fast repetitive rate (more than 2 kHz). The parameters of the system are in the range of 350 kV peak voltage, 15 ns rise time, 50 ns pulse width and 115 Hz repetitive rate.

PIM-a Blumlein driven IVA machine

Abstract: The PIM machine has been designed and constructed at AWE to develop IVA technology for flash radiography of hydrodynamic experiments. While it was originally conceived as one module of a ten module, 14 MV, 100 kA machine versions operating at up to 3 MV are of interest to satisfy future radiographic applications at AWE. The IVA architecture will enable these machines to be relatively easily configurable in either negative or positive polarity allowing the diode to be either the self magnetic pinch type already in use at AWE or a rod pinch diode to achieve smaller radiographic spots. A Marx generator drives a 1.7 MV, 10 ohm water Blumlein initiated by twin radial laser triggered switches. The Blumlein has been used to drive either one or two parallel inductive cavities to obtain an output of 1.5 or 3 MV with a current of up to /spl sim/150 kA or >50 kA respectively. Prepulse suppression is provided by a gas prepulse switch in the coaxial oil feed from the Blumlein to the cell or cells. The latest results of the testing of the laser triggering system and the prepulse reduction system will be presented.

Fragmentation of Refuse Circuit Board using Pulsed Power Discharges in Water

Abstract: Fragmentation using pulsed power discharges in water seems one of promising methods for recycling of refuse circuit boards in electrical appliances. The Marx generator, which provides voltage of up to 480 kV and energy of up to 7.7 kJ, was employed to produce the electrical discharges in water. Refuse circuit boards were successfully broken into small pieces, and the circuit elements were separated from the boards after several tens of discharges. The amount of fragmentation is dependent on energy supplied from the Marx generator. Also the fracturing mechanism of circuit boards is described.

Characteristics of an intense relativistic electron beam in a MILO geometry

Abstract: The Magnetically Insulated Line Oscillator (MILO) is a high power crossed-field microwave pulsed tube, potentially of gigawatt power, that combines the technologies of magnetically insulated electron flow with a slow wave structure. It became popular during the last decade for defence applications. Electrical energy is delivered to the tube from a high voltage Marx generator connected through a coaxial transmission line. Electrons are emitted in vacuum from a cylindrical velvet cathode and interact with an electromagnetic field induced in the anode structure. In our example, the central part of the anode is a four cell resonator, i.e. the MILO is an extended interaction oscillator. Microwave energy is reflected from the left end of the resonator by the choke cavity. Output coupling of the cavity is determined by the geometry of the extractor vane and the collector. The periodic delay line whose cell is similar to that of the anode is a slow wave structure with phase velocity less than the speed of light. Synchronism between the drift velocity of the electrons and the phase velocity of the infinite line allows an RF field component to grow, leading to microwave generation. High power microwaves (HPM) propagate forward along the tube and are extracted through a Vlasov antenna. Our aim is to design and to build a compact tube in MILO-type structure. In this paper, we report on the first step of the work, namely retrieving all the tube characteristics when all dimensions are one half of the ones by Lenke et al. (1997). The numerical simulation was performed using MAGIC, an electromagnetic PIC software. This study is also of interest to scale the pulsed power generator driving the tube. (4 pages)

Design of Q-switching High Voltage Pulse Generators with Nanosecond Rise Time

Abstract: A generator which can produce high voltage pulse with nanosecond rise time was designedThe generator is based on the use of avalanche transistor in a Marx Bank circuitAs a result,Qswitching speed increases from 90 ns to less than 20 ns,peak power of output pulse increases from 25 mW to 93 mW and pulse width decreases from 16 ns to 8 nsThe generator has many merits such as small bulk,low power consumption,low EMI,high repetition rate,long operating life etc

Pre-pulse suppression on Eros at AWE

Abstract: The Eros facility at AWE was designed to simulate radiation effects using a large area diode driven by a low impedance Blumlein charged by a Marx generator. Recent interest at AWE to develop low impedance, high current pinched diodes, have lead to a need to use Eros for these experiments. Unfortunately Eros has no pre-pulse suppression beyond the balancing circuit that evens out the charging of the inner and outer lines of the Blumlein. This allows a pre-pulse of +/- 100 kV to reach the diode during the charging phase of the machine, too high a level for pinched diodes. To reduce the pre-pulse two options were considered, both of which are needed: 1) to install a pre-pulse gap into the stalk of the MITL; and 2) to install rail gap switches between the inner cylinder of the Blumlein and the insulator stack. The stalk pre-pulse gap was demonstrated to work on Eros improving self-magnetic pinch diode performance. The rail gaps were designed and then fitted during the year. Together these switches reduced the total pre-pulse on the diode by a factor of eight.

Two ZR Marx generator operating configurations that make possible their rolling upgrade integration into Z

Abstract: If the Sandia National Laboratories' Z-Machine Marx generators and the Z-refurbishment (ZR) Marx generators are mixed to drive like-modules in parallel, the ZR banks need to be temporarily reconfigured to closely match the output waveforms of the Z banks. Otherwise, there is significant module-to-module variations and a loss of consistency at the central target region. Sandia has explored two solutions for operating the ZR Marx generators to meet this requirement. One method involves charging the ZR banks to about 72 kV along with the 90-kV charge for the Z banks, thus requiring two power supplies and charge busses plus a different SF/sub 6/ pressure in the Marx switches. The other method is to short or bypass an appropriate number of ZR Marx stages so the remaining "reduced" Marx generator may be charged to the same 90-kV level. Some hardware, labor, and bank inductance tuning are needed to match output timing to the original pulsed power. This paper examines how to implement both solutions and compares their advantages and disadvantages with the goal of choosing only one of them. Models supporting this effort take into account measurements obtained from existing Marx generators that are reconfigured in similar ways.

Compact flash x-ray generator (MFXG-02) and its applications

Abstract: Aiming to realization of compact flash x-ray facilities, flash x-ray generator with two-stage Marx generator and a krytron pulse generator was constructed and its characteristics were verified in present study. Target and cathode of the x-ray tube was tungsten rod and graphite disk plate, respectively. Two-stage Marx generator applied high voltage to the target and discharge between electrodes produced plasma and x-ray. Experiments revealed the relationship between tube voltage, tube current and applied voltage to x-ray tube. Effect of distance from target to cathode was also made clear. Measurement of radiation output with plastic scintillator indicated the shorter pulse duration than 100 ns and the effect on application of present experimental configuration to high-speed photography. Radiographs were taken with computed radiography (CR) system. The photographs displayed enough resolution to perform fine photography and existence of soft x-ray for wide purposes. Present study implies application of present simple x-ray system to realization of compact and general-purpose x-ray generator.

Fast discharge energy storage development for improving X-ray simulators

Abstract: Design studies have been completed to investigate the impact of improvements in fast energy storage systems on the designs of: larger future simulators (such as a 15-MA PRS simulator), simulator upgrades of operational machines (such as double-EAGLE), and for very compact, smaller simulators. The fast energy storage system that has been investigated and is presently under development (see companion papers) is a fast Marx generator (FMG) with (LC)/sup 1/2/ = 200 ns and (LC)/sup 1/2/ = 300 ns, depending on the capacitance per stage. This new fast Marx energy storage system uses newly developed, low-inductance rail switches and low-inductance capacitors. These components are configured in a low-inductance FMG stage and then stacked in series to form a unit for the voltage required and a number of units in parallel for the required system inductance and stored energy. A four-stage fast Marx prototype has been demonstrated with a total of 60 kJ energy stored and an output voltage of 680 kV. A design sketch of a 15-MA PRS machine driven by a fast Marx will be presented. This generator would consist of 48 eight-stage FMG units and would drive the PRS directly without further pulse compression. The second concept presented will be a very compact e-beam or Bremsstrahlung machine. This concept will consist of an eight-stage FMG driving a vacuum-inductive store. The vacuum store will be switched into an e-beam load using a plasma opening switch (POS).

A new diode system for high fluence electron beam

Abstract: For flashII accelerator a new diode system was developed including a low impedance diode with a flash switch, drift tube, pulsed magnetic system and vacuum target chamber. Its electron beam fluence is three times more than that of the old diode system. By means of decreasing the diameter of cathode, increasing axial magnetic intensity and magnetic lens ratio, and adjusting the distance of flash switch and the pressure of prepulse switch a stable working regime of the diode with high fluence electron beam was achieved. While charging 70 kV into Marx generator electron beam of 21.5kJ total energy, spot diameter 52mm and energy fluence 1.01kJ/cm2 on target at a distance 22cm from cathode was acquired.

Reliable Self-Starting Simmer Circuit for a Marx-Bank Driver

Abstract: A reliable self-starting simmer circuit for use as a Marx-bank driver, in which a stable glow discharge is obtained using the high voltage main power supply instead of an additional simmer power supply, is presented. Highly energetic excitation sources having very short pulse width are needed in powerful dye and excimer lasers. For this reason, multi-stage Marx-bank circuit and LC inversion circuits have been developed. However, these circuits have defects in the interference between the main discharge circuit and the pre-ionization circuit, and an occasional switching failure of the spark gap switch, resulting in an unstable main discharge. The circuit presented seeks to address these issues.

X-ray unit for the generation of brief X-ray pulses and inspection device operating with such an X-ray unit

Abstract: An invention related to an X-ray device for the generation of brief X-ray pulses comprising an X-ray tube having a thermionic cathode and an anode and an X-ray generator having a first circuit for the generation of a high-voltage pulse which is applied to the anode for the generation of the X-ray pulse. The X-ray generator further comprising a second circuit by which a low voltage is continuously applied to the anode which pre-heats the X-ray tube and is at most sufficient for the generation of low-energy X-radiation. The first circuit can have a high-voltage power supply unit which charges a high-voltage capacitor which can be applied to the anode via a high-voltage switch. The first circuit can be a Marx generator. There may be only one power supply, which both generates the continuously low voltage and also drives the Marx generator for the generation of the high voltage. The X-ray unit can be part of an apparatus for the inspection of objects which has an imaging apparatus for the generation of an image of the object by means of the X-ray.

The Z-20 reliability calculations

Abstract: The Z-20 is a pulsed power facility designed to test the characteristics of water switches to be used in the ZR project. The facility consists of a Marx generator feeding into a water dielectric intermediate store (IS), the IS discharges through a gas switch into a water dielectric pulsed forming line (PFL), goes through the water switches into a water dielectric flat tri-plate transmission line (t-line) matched to a resistive load. The facility was also used to determine the effects of an abrupt, coaxial to flat plate, T-line transition in the water switch region, and the use of large flat dielectric plates to separate anode and cathode from the coaxial PFL. An extended technique to calculate the probability of failure, of large surface area water systems, was used to estimate the reliability of the Z-20 system. With this technique we integrated the probability of failure, after partitioning the surface in small steps, with the advantage that the "enhanced" regions get automatically included in the calculation. The system has been operating at voltage levels above 4 MV with more than 400 shots accumulated without a single failure in the water region.

Single shot overstressing of high voltage capacitors for compact Arkadiev-Marx generator

Abstract: Five different types of high voltage capacitors have been tested to determine their maximum high voltage overstress coefficient. Chicago condenser, Reynolds industries, Hivolt, and TDL capacitors of capacitance 100 nF and different nominal voltages were tested in the single shot mode. Experiments have shown that the energy stored under overstress conditions in all types of the capacitors tested is 10 to 20 times more than the nominal energy.

Numerical and experimental study of a coaxial pulsed power device for generation of XUV radiation

Abstract: Most of the pulsed power devices use a transmission element between a capacitor-based generator and the load. In the case of our studies, a soft x-ray laser fed by capillary discharge, we have built a pulse power driver made of a four-stage Marx generator, a coaxial formation line, a self-triggered spark gap, and a coaxial transmission line at the end of which the capillary tube is connected. We present a numerical model of the electric behavior of the system, which allows to calculate the temporal evolution of the voltage and intensity in any point of the circuit, and specifically any point of the coaxial lines. Comparison with experimental measurements shows good agreement. The model can be extended to other configurations like radial or plate lines. It can help in the design of these lines in order to maximize the transmission of energy from the generator to the load. It can also be used as a tool for education purpose, since it permits to apprehend the electric behavior of pulsed power devices.