Showing papers on "Marx generator published in 1997"
01 Aug 1997
TL;DR: PBFA Z as discussed by the authors is a new 60 TW/5 MJ electrical driver located at Sandia National Laboratories, which can achieve peak currents of 16-20 MA with a rise time of 105 ns, depending on the initial load inductance and the implosion time.
Abstract: PBFA Z is a new 60 TW/5 MJ electrical driver located at Sandia National Laboratories. The authors use PBFA Z to drive Z pinches. The pulsed power design of PBFA Z is based on a conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 60 TW/105 ns pulse to the output water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the Z-pinch load. Depending on the initial load inductance and the implosion time, one attains peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the Z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical-disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The authors achieved X-ray powers of 200 TW and X-ray energies of 1.9 MJ from a tungsten wire-array Z-pinch loads.
42 citations
29 Jun 1997
TL;DR: In this paper, the authors proposed a fast linear transformer driver (LTD), which provides high efficiency of energy transfer into the secondary turn and the current rise time below /spl sim/1 CLs, because of relatively high inductance of the caps and the switches.
Abstract: The main advantage of the primary storage based on linear transformer scheme is the ground potential on the capacitor bodies during the shot, allowing exclusion of the total output voltage insulation of the highest stages, and to trigger all the stages simultaneously by using an external trigger pulse. The problem was to build a fast linear transformer driver (LTD), providing both high efficiency of energy transfer into the secondary turn and the current rise time below /spl sim/1 CLs, because of relatively high inductance of the caps and the switches. The key elements of the LTD described below are the HAEFELY capacitors (75 kV, 5.65 /spl mu/F, 13 nH, 40 mOhm, or 90 kV, 3.95 /spl mu/F, 10 nH, 13 mOhm) and the multi gap, multi channel spark switches developed at HCEI for SYRINX project (90 kV, 0.7 MA, 8.5 nH). This LTD was designed as an alternative to the Marx generator in order to improve the performance of the IES technology in the direct drive approach where the only unit providing power multiplication on the load is the POS. The LTD was designed as a single stage with two HAEFELY caps in parallel. The authors describe a 75 kV LTD stage with oil insulation and a 90 kV LTD stage with SF/sub 6/ insulation.
33 citations
TL;DR: The GIT16 facility as discussed by the authors was designed to improve the technology for forming high-power pulses using intermediate inductive storage and a circuit breaker in the form of a plasma opening switch and to investigate radiating loads of the Z-pinch type.
Abstract: A description is given of the GIT16 facility, designed to improve the technology for forming high-power pulses using intermediate inductive storage and a circuit breaker in the form of a plasma opening switch and to investigate radiating loads of the Z-pinch type. The characteristics of the individual components of the facility are given and the main results characterizing the behavior of the microsecond plasma opening switch are given for currents of several megamperes.
24 citations
29 Jun 1997
TL;DR: In this article, the SCREAMER and TL codes were used to design the z-pinch modification of PBFA II, which is now called Z. Good agreement between the measured waveforms and design simulations has been achieved.
Abstract: The SCREAMER and the TL codes were used to design the z-pinch modification of PBFA II, which is now called Z. In the design phase an equivalent voltage was used to initiate the simulations. Good agreement between the measured waveforms and design simulations has been achieved. Full-circuit, shortened-circuit, and equivalent-circuit simulations have been used. All use a loss model that discards the plasma current in the vacuum magnetically insulated transmission lines (MITLs) at the post hole convolute (PHC). Voltage measurements provide an equivalent voltage which is used as a starting point for four-level circuit and equivalent-circuit simulations. Both full-circuit and shortened-circuit simulations use a four-line model. The thirty-six lines are lumped into four, nine-line equivalent circuits. The full circuit includes the erected Marx bank, the intermediate store water capacitor, the laser-triggered spark gap, the line 1, 2 and 3 pulse forming lines, the coax to biplate transition, the water biplates, the vacuum stack with water and vacuum flares, the MITLs, the PHC, and the z-pinch load. Because of the difficulty in making load current measurements, the model has been used to infer load current and implosion characteristics. The model has also been used to predict optimal pinch load configurations.
22 citations
29 Jun 1997
TL;DR: In this article, the development of a compact Marx generator to drive loads with impedances on the order of 10 ohms is discussed, and the entire assembly is housed in a 1.2 m diameter aluminum pipe pressurized with 30 psig sulfur hexafluoride.
Abstract: One of the goals of the High-Energy Sources Division of the Advanced Weapons and Survivability Directorate at the Phillips Laboratory is to develop high-power microwave sources and their related pulsed power. Here, the development of a compact Marx generator to drive loads with impedances on the order of 10 ohms is discussed. It is an 8 stage design, 4 stages charged to +100 kV and 4 stages charged to -100 kV, that stores 19.2 kJ at full charge. The Marx, excluding the trigger generator, has a diameter of 0.9 m and a height of 0.7 m. The entire assembly is housed in a 1.2 m diameter aluminum pipe pressurized with 30 psig sulfur-hexafluoride. The same sulfur-hexaflouride that insulates the Marx from its container also serves as the working gas in the gas-insulated switches of the Marx. In experiments to date, the Marx has been fired hundreds of times at full voltage into loads varying in impedance from 5 to 10 ohms. The design and fabrication of the Marx generator and the experimental results are given.
16 citations
TL;DR: In this paper, a new type of pulse transformer has been developed as a substitute for a Marx generator, where amorphous metallic cores are utilized with windings of cylindrical conductors.
Abstract: A new type of pulse transformer has been developed as a substitute for a Marx generator. In the transformer amorphous metallic cores are utilized with windings of cylindrical conductors. As a result, low leakage inductance is realized with high breakdown strength. The coupling coefficient of the transformer is estimated to be more than 0.99. By using the transformer of winding ratio of 1:3, a Blumlein pulse forming line of capacitance 20 nF is successfully charged up to 270 kV by using a capacitor bank of 240 nF, 90 kV. High speed charging of charging time=250 ns is realized with high efficiency of energy transfer (energy transfer efficiency from the capacitor bank to the pulse forming line was evaluated to be 76%).
15 citations
TL;DR: In this article, the results from a cold cathode magnicon experiment at 11.12 GHz, driven by a single-shot Marx generator, were presented, with a predicted efficiency in excess of 60%.
Abstract: The magnicon is a scanning-beam microwave amplifier that is being developed as a high power, highly efficient microwave source for use in powering the next generation of high gradient electron linear accelerators. This article first discusses the results from a cold cathode magnicon experiment at 11.12 GHz, driven by a single-shot Marx generator. Following this, a design is presented for a new thermionic magnicon experiment to produce more than 50 MW at 11.4 GHz, using a 210 A, 500 kV beam from an ultrahigh convergence thermionic electron gun driven by a repetition-rated modulator. This new design has a predicted efficiency in excess of 60%.
15 citations
12 May 1997
TL;DR: PBFA Z as mentioned in this paper is a new 55 TW/4.5 MJ short pulse electrical driver located at Sandia National Laboratories, which achieved peak currents of 16-20 MA with a rise time of 105 ns.
Abstract: PBFA Z is a new 55 TW/4.5 MJ short pulse electrical driver located at Sandia National Laboratories. We use PBFA Z to magnetically-implode plasma shells. These configurations are historically known as Z pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 4.5 MJ in 55-TW/105-ns pulse to the output water transmission lines, and delivers up to 3.0 MJ and 40 TW of electrical energy to the Z-pinch load. Depending on the initial load inductance and the implosion time, we attain peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the Z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The measured system performance of the water transmission lines, the vacuum insulator stack, the MITLs, and the double post-hole vacuum convolute differed from preshot predictions by /spl sim/5%. Using a 2-cm radius and a 2-cm length tungsten wire array with 240, 7.5-/spl mu/m diameter wires (4.1-mg mass) as the Z-pinch load, we achieved X-ray powers of 200 TW and X-ray energies of 1.85 MJ as measured by X-ray diodes and resistive bolometry.
9 citations
TL;DR: In this paper, a fast discharge-switch-free Blumlein pulse forming line was developed for high-voltage pulsed power generation, where a saturable charging inductor of amorphous metallic core is utilized and, as a result, fast-charging (charging time ≈220 ns) is obtained with a reduced prepulse.
Abstract: A fast-charging, discharge-switch-free Blumlein pulse forming line has been developed for high-voltage pulsed power generation. In the BL, a saturable charging inductor (CI) of amorphous metallic core is utilized and, as a result, fast-charging (charging time ≈220 ns) is obtained with a reduced prepulse. In addition, by using CI as a step-up transformer, the impedance of the output pulse can be converted to 4Z, Z, Z/4. By using the BL with a Marx generator of 300 kV and 1.1 kJ, an output of —580 kV at 24 kA and a pulse length of 60 ns are obtained, with a current rise time of less than 16 ns. The energy transfer efficiency of the line (output pulse energy/charging energy of a pulse forming line) is evaluated to be more than 92%.
7 citations
01 Jun 1997
TL;DR: The Decade Quad (DQ) is a high power generator that will be built at Arnold Engineering Development Center (AEDC) in Tullahoma, Tennessee by the Defense Special Weapons Agency (DSWA) as mentioned in this paper.
Abstract: The Decade Quad (DQ) is a high power generator that will be built at Arnold Engineering Development Center (AEDC) in Tullahoma, Tennessee by the Defense Special Weapons Agency (DSWA). The DQ will consist of four independent command triggered pulsed power modules. The building at AEDC has been completed and has the capacity to accommodate up to four DQ machines for a total of 16 modules. Two full power modules (DM1 and DM2) have been built and tested to verify the Decade design at PRIMEX Physics International. Each module consists of a 5’70 kJ Marx generator that pulse charges a water transfer capacitor. The transfer capacitor discharges into a water output line through an array of six parallel triggered gas switches. The water output line then pulse charges the inductive store/opening switch pulse compression stage. When the opening switch opens, the inductive store discharges into an electron beam bremsstrahlung diode load. Two full power prototype modules have been built and tested into electron beam bremsstrahlung loads. Over 3508 mdchine shots have been taken on the two modules. The measured pulsed power and the radiation output performance from the single module has been used to predict the radiation output from the Decade Quad. The new machine will be capable of producing 16 krads(Si) over a 2250 cm2 test area with a 47 ns radiation pulse width. A future upgrade of the Decade Quad is planned to provide the capability to drive imploding plasma radiation loads for soft (1-5 keV) x-ray production. A design sketch of the Decade Quad pulsed power configuration for driving a plasma radiation source has been completed. The Decade Quad circuit model has been coupled to an imploding load model to quantify the effects of the I x Mot voltage on the pulsed power system and to estimate the kinetic energy delivered to the load. A range of implosion times and inductances were assessed to determine the optimum low risk design configuration.
7 citations
TL;DR: In this article, a coaxial Marx generator with a UV laser pulse propagating coaxially through multigap switches is constructed, which is operated at a maximum voltage of 200 kV with a rise time of less than 10 ns.
Abstract: A coaxial Marx generator triggered with a UV laser pulse propagating coaxially through multigap switches is constructed. The Marx generator is operated at maximum voltage of 200 kV with a rise time of less than 10 ns. To trigger multigap switches in the Marx generator, the laser pulse is passed through fine metal mesh fitted in the holes formed along the central axis in electrodes of gap switches. Photoelectrons generated from the mesh part of the cathode trigger the discharge and close the switches. Timing jitter of the high voltage pulse with respect to the laser pulse is 800 ps for the case of single gap switch and 1 ns for the Marx generator with two stage gap switches. Since the spark path is always formed from the solid surface of the cathode instead of the metal mesh, the mesh part of the cathode is never damaged for a large number of shots, promising long lifetime of the electrodes.
29 Jun 1997
TL;DR: In this paper, a 32-stage Marx generator with a pulse forming network (PFN) was designed for a load in the range of 300 to 700 /spl Omega/ to achieve a low jitter requirement.
Abstract: The experimental results of a 32-stage Marx generator are presented. A pulse forming network (PFN) was added to each stage of the Marx to lengthen the pulse width to 500 ns. The "PSpice" simulation shows that PFN-Marx generator can be reduced to the basic circuit of a discharge line pulse generator. The system is designed for a load in the range of 300 to 700 /spl Omega/. To achieve the steep rise in the voltage pulse and meet a low jitter requirement, UV-coupled spark gap switches are employed in the system. With an added pulse sharpening technique, it is possible to reduce the risetime to a few nanoseconds, or to several hundreds of picoseconds if it is required.
TL;DR: In this article, the two final amplifiers of the Nike laser are both electron-beam-pumped systems, with an emphasis on the pulsed power, and they are complete, fully integrated into the laser, meet the Nike system requirements, and are used routinely for laser target experiments.
Abstract: Nike is a recently completed multikilojoule krypton-fluoride (KrF) laser that has been built to study the physics of direct-drive inertial confinement fusion. The two final amplifiers of the Nike laser are both electron-beam-pumped systems. This paper describes these two amplifiers, with an emphasis on the pulsed power. The smaller of the two has a 20/spl times/20 cm aperture, and produces an output laser beam energy in excess of 100 J. This 20 cm Amplifier uses a single 12 kJ Marx generator to inject two 300 kV, 75 kA, 140 ns flat-top electron beams into opposite sides of the laser cell. The larger amplifier in Nike has a 60/spl times/60 cm aperture, and amplifies the laser beam up to 5 W. This 60 cm amplifier has two independent electron beam systems. Each system has a 170 kT Marx generator that produces a 670 kV, 540 kA, 240 ns Bat-top electron beam. Both amplifiers are complete, fully integrated into the laser, meet the Nike system requirements, and are used routinely for laser-target experiments.
02 May 1997-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the authors explored the possibility of increasing the charge states of metal ions to facilitate high-energy, broad beam ion implantation at a moderate voltage level, using a time-of-flight (TOF) technique.
Abstract: Ion energy of the beam formed by an ion source is proportional to extractor voltage and ion charge state. Increasing the voltage is difficult and costly for extraction voltage over 100 kV. Here we explore the possibility of increasing the charge states of metal ions to facilitate high-energy, broad beam ion implantation at a moderate voltage level. Strategies to enhance the ion charge state include operating in the regimes of high-current vacuum sparks and short pulses. Using a time-of-flight (TOF) technique we have measured charge states as high as 7 + (73 kA vacuum spark discharge) and 4 + (14 kA short pulse arc discharge), both for copper, with the mean ion charge states about 6.0 and 2.5, respectively. Pulsed discharges can conveniently be driven by a modified Marx generator, allowing operation of “Magis” with a single power supply (at ground potential) for both plasma production and ion extraction.
29 Jun 1997
TL;DR: The Decade Quad (DQ) is a high power generator that will be built at Arnold Engineering Development Center (AEDC) in Tullahoma, Tennessee by the Defense Special Weapons Agency (DSWA) as mentioned in this paper.
Abstract: The Decade Quad (DQ) is a high power generator that will be built at Arnold Engineering Development Center (AEDC) in Tullahoma, Tennessee by the Defense Special Weapons Agency (DSWA). The DQ will consist of four independent command triggered pulsed power modules. The building at AEDC has been completed and has the capacity to accommodate up to four DQ machines for a total of 16 modules. Two full power modules (DM1 and DM2) have been built and tested to verify the Decade design at PRIMEX Physics International. Each module consists of a 570 kJ Marx generator that pulse charges a water transfer capacitor. The transfer capacitor discharges into a water output line through an array of six parallel triggered gas switches. The water output line then pulse charges the inductive store/opening switch pulse compression stage. When the opening switch opens, the inductive store discharges into an electron beam bremsstrahlung diode load. Two full power prototype modules have been built and tested into electron beam bremsstrahlung loads.
29 Jun 1997
TL;DR: In this paper, a high voltage, sub-nanosecond pulser is designed and built for the purposes of investigating dielectric breakdown, which is achieved by using pulse sharpening techniques on the output of a 500 kV Marx bank.
Abstract: A high voltage, sub-nanosecond pulser is designed and built for the purposes of investigating dielectric breakdown. The requirement for the pulser is a voltage pulse of several hundred kilovolts, pulsewidth less than a few nanoseconds, and a risetime <400 psec. This is achieved by using pulse sharpening techniques on the output of a 500 kV Marx bank. Originally designed to stimulate a lightning strike, the voltage waveform from the Marx generator has a slow decay time of tens of /spl mu/sec. In order to obtain a more desirable pulse, the Marx bank is modified. By removing a lumped-element resistor a higher peak output voltage with a faster risetime can be obtained. Circuit simulations have shown the capability of achieving an 800 kV output in less than 40 nsec to a charging (pulse forming) line. The 50 /spl Omega/ impedance, oil-filled, pulse forming line consists of a peaking gap and pulse slicing gap. The peaking gap decreases the risetime of the applied pulse down to about 300 psec. The pulse slicing gap is included to short the voltage applied to the delay line and test chamber.
29 Jun 1997
TL;DR: A compact four stage Marx with six parallel Marx generators per stage and a common switch housing was developed for various Air Force applications as mentioned in this paper, which can use six independent spark gaps or one continuous ring gap packaged in a housing measuring 76 cm in diameter, 56 cm in height and 295 kg.
Abstract: A compact four stage Marx with six parallel Marx generators per stage and a common switch housing, developed for various Air Force applications, is described Unique features of the compact Marx include a single cast epoxy switch housing common to each stage that can use six independent spark gaps or one continuous ring gap packaged in a housing measuring 76 cm in diameter, 56 cm in height and of 295 kg Initial test results of the Marx into a 5 /spl Omega/ resistive load and rep-rate performance of the Marx's four stage 160 kV open air trigger Marx, are discussed Individual Marx stages were designed to operate with a maximum bipolar +/-50 kV charge and erected capacitance of 60 nF providing a per pulse energy of 48 kJ Design goals were to provide a 500 ns wide pulse with a 100 ns rise time into the 5 /spl Omega/ load The spark gaps and capacitors are arranged radially at sixty degree intervals, and the latter are connected with simple banana plugs to provide easy removal The switches are designed to operate with dry air pressurized to 80 psig, and the Marx was designed to be submerged in dielectric oil The first stage of the Marx is triggered by the four stage 160 kV trigger Marx Pulsed operation at several hertz was investigated for burst mode operation with and without gas flow Possible investigation of an eight stage 800 kV Marx is contemplated
29 Jun 1997
TL;DR: In this article, a modular highvoltage device, forming in its load electric pulses with amplitudes of 100-200 kV, current 400-800 kA and duration 20 ns is described.
Abstract: A modular high-voltage device, forming in its load electric pulses with amplitudes of 100-200 kV, current 400-800 kA and duration 20 ns is described. The device is intended for the generation of Bremsstrahlung pulses. The device is made on the basis of four generators of GIIR-4/sup 1/ type. Their high accuracy of triggering allows synchronous module operation. The load of the GIIR-4 is either 42 high-voltage cables of KVI-300 type, or a transforming line with a transformation coefficient of 2. The peculiarity of the module is the simultaneous joint charging of the GIIR-4 forming lines and the HV synchronization block from one Marx generator. This allowed an increase in the reliability of device operation and repetition rates up to 20 Hz. Data on module experiments and data concerning the operation resources of the mostly electric strength device units are also presented.
29 Jun 1997
TL;DR: In this paper, the authors describe a water-filled passive crowbar switch which is employed to divert energy away from sensitive loads at voltage levels up to 600 kV. The switch is comprised of a highly nonuniform field electrode configuration immersed in de-ionised water.
Abstract: This paper describes the development of a water-filled passive crowbar switch which is employed to divert energy away from sensitive loads at voltage levels up to 600 kV. The crowbar is self-closing and does not require electrical triggering. The time delay to crowbar operation is determined by the magnitude of the applied impulse voltage and the switch gap spacing. The switch is comprised of a highly nonuniform field electrode configuration immersed in de-ionised water. Electrostatic field analysis of the switch was carried out in order to optimise the insulation performance of the device prior to testing. Characterisation of the passive crowbar switch was accomplished using a Marx generator as the impulse voltage source, and by measuring the time delay to breakdown for different values of applied voltage and electrode spacing. The results have shown that the crowbar design is capable of operating at voltages up to 600 kV.
19 Mar 1997
TL;DR: In this paper, a five-stage PFN Marx generator was used to discharge a single sphere-sphere spark gap with no gas flow and the results indicated that the PRF capability was not adversely affected when a spark gap column is used to erect it.
Abstract: This paper describes some results on the repetitive performance of a five stage spark gap column which was used to discharge a five stage PFN Marx generator. The results presented indicate that the PRF capability of the PFN Marx generator is not adversely affected when a spark gap column is used to erect it. The PRFs observed in air, SF/sub 6/ and a 50% SF/sub 6//50% He mixture were similar to those which may be expected to be observed in a single, isolated sphere-sphere spark gap with no gas flow. The measurements indicate that SF/sub 6/ is more suited to repetitive operation than air, possibly because of its superior convective properties and strong electronegativity. The addition of He to SF/sub 6/ appears to enhance the PRF, but for a 50%/50% mixture ratio there is a corresponding reduction in the self-firing voltage of the generator.
29 Jun 1997
TL;DR: In this article, a 10 stages, one capacitor per stage Marx generator is presented, whose parameters are as follows : 90 kV charging voltage, 160 kJ stored energy, 670 nH internal inductance, 470 kA peak current, and a 700 ns current risetime.
Abstract: This work is part of technological developments carried out within the SYRINX project in order to implement future multi megajoules drivers, using the multi module inductive energy storage (IES) concept. One of the two 640 kJ IES modules developed for that purpose requires a compact, sub-microsecond Marx generator. This paper presents first results on a 10 stages, one capacitor per stage Marx module whose parameters are as follows : 90 kV charging voltage, 160 kJ stored energy, 670 nH internal inductance, 470 kA peak current, and a 700 ns current risetime. Specific capacitors, gas switches and connections have been developed in the scope to reach stringent requirements in terms of low inductance value, high current switching, voltage insulation and reliability. Performances of those components and of the complete Marx including erection process and voltage and current diagnostics for various loads (short circuit, 0.5 /spl Omega/ and 2.1 /spl Omega/ resistances) are presented. Those results are correlated with numerical simulations using the circuit analysis code PSPICE.
01 Mar 1997
TL;DR: In this paper, the results from a cold cathode magnicon experiment at 11.12 GHz, driven by a single-shot Marx generator, were discussed, and a new thermionic magnicon was designed to produce more than 50 MW using a 210 A, 500 kV beam from an ultrahigh convergence thermionic electron gun driven by rep-rated modulator.
Abstract: The magnicon is a scanning-beam microwave amplifier that is being developed as a high power, highly efficient microwave source for use in powering the next generation of high gradient electron linear accelerators. In this paper, we first discuss the results from a cold cathode magnicon experiment at 11.12 GHz, driven by a single-shot Marx generator. We then present the design of a new thermionic magnicon experiment to produce more than 50 MW at 11.4 GHz, using a 210 A, 500 kV beam from an ultrahigh convergence thermionic electron gun driven by a rep-rated modulator. This new design has a predicted efficiency in excess of 60%.
25 May 1997
TL;DR: In this article, a planar-type electric field measuring system has been developed, which consists of optical fiber links to prevent the effect of electromagnetic disturbances, and its frequency bandwidth was the range from 12 Hz to 12 MHz with an amplification factor of 5.
Abstract: The transient electric fields, which originate from the operations of a high voltage experimental apparatus and Marx generator, were measured and analyzed by means of the Fast Fourier Transform (FFT) method. The planar-type electric field measuring system has been developed. The signal transmission system consists of optical fiber links to prevent the effect of electromagnetic disturbances. The electric field measuring system showed a very good step response characteristic and its frequency bandwidth was the range from 12 Hz to 12 MHz with an amplification factor of 5.
29 Jun 1997
TL;DR: In this paper, a Marx bank was used to produce a single-shot impulse waveform with a peak voltage of 600 kV, having 15 kJ of energy, a Marx Bank was used which had six 100kV, 0.5 /spl mu/F capacitors arranged in six stages, charged in parallel and discharged in series.
Abstract: To produce a single-shot impulse waveform with a peak voltage of 600 kV, having 15 kJ of energy, a Marx Bank was used which had six 100 kV, 0.5 /spl mu/F capacitors arranged in six stages, charged in parallel and discharged in series. The overall performance and reliability of this Marx Bank was improved by inserting new high power, noninductive resistors in the discharge circuit to dissipate excess energy resulting from switch misfires and load faults. Among the specific technical design issues addressed is the development of a new nondestructive examination technique (NDET) for different modes of Marx Bank operation, which determines if output load faults or switch misfires will be safely tolerated by the resistors used in the charge/discharge circuits. Initial results, including computer simulations and laboratory measurements, using a new fault protecting, energy-absorbing resistor placed in series with the Marx output load are presented. Also, circuit design recommendations for further reduction in fault energies dissipated in the tail resistors of a misfired stage are discussed. As well as the elimination of current ringing from the fault-protecting resistor under fault conditions is described.
29 Jun 1997
TL;DR: In this paper, a small Marx generator, a ring up inductor and a vacuum feedthrough bushing and insulator sample are used to measure charge injection into insulators using high voltage pulses.
Abstract: An experiment has been designed to measure charge injection into insulators using high voltage pulses. In order to limit the area of charge injection, point plane geometry and low energies are used. These low energies are achieved by using a small Marx generator, a ring up inductor and a vacuum feedthrough bushing and insulator sample to provide a CLC ringup. Connecting the ground plane behind the sample introduces a second inductance which produces a second mesh in the equivalent circuit. Charge injection into the insulator provides a short risetime pulse which excites the second mesh. Monitoring the excitation of the current in this second mesh provides charge injection information. The erection of the Marx generator via spark gaps is a source of high frequency electrical noise which also excites the second mesh and therefore must be reduced if charge injection information is to be obtained. Inserting ferrite cores of proper frequency response between stages of the Marx generator, as well as on both sides of the ring up inductor, is shown to reduce the erection noise. This noise reduction is demonstrated by a decrease in the excitation of the high frequency resonant mesh. With the ferrite cores inserted the amplitude of the second mesh excitation is 20% of what it is without the ferrites.
19 Mar 1997
TL;DR: In this article, the authors proposed a new concept of the inductive line for energy storage (ILES), in which part of these inductances are replaced by suitable transmission line elements, which offers a significant improvement in the maximum current and hence energy delivery to an inductive load.
Abstract: The inductive energy storage (IES) generator has long been considered to be the most efficient system for energy usage in large pulsed power systems in the MA level. A number of parameters govern the efficiency of energy transfer between the storage capacitors and the load, and the level of current deliverable to the load. For a high power system, the energy storage capacitors are arranged as a Marx generator. The primary constraints are the inductances in the various parts of the circuit, in particular, the upstream inductance between the Marx and the plasma opening switch (POS), and the downstream inductance between the POS and the load. In this paper, we propose a new concept of the inductive line for energy storage (ILES), in which part of these inductances are replaced by suitable transmission line elements. Extensive parametric scans have been carried out on circuit simulations to investigate the effect of both the upstream and downstream transmission lines. Comparison with an existing IES generator shows that the ILES design offers a significant improvement in the maximum current and hence energy delivery to an inductive load.
01 Sep 1997
TL;DR: By distributing control points close to the systems being controlled the authors expect to simplify the task of isolating electonic systems from the large expected EMI pulses, allow connection of the various parts of the system by high-level fiber-optic networks, allow a simple configuration of the control and data acquisition screen rooms, and simplify the software efforts through the resulting modularization.
Abstract: The control and data acquisition systems for Atlas will use a large degree of decentralization. By distributing control points close to the systems being controlled we expect to simplify the task of isolating electonic systems from the large expected EMI pulses, allow connection of the various parts of the system by high-level fiber-optic networks, allow a simple configuration of the control and data acquisition screen rooms, and simplify the software efforts through the resulting modularization. The Atlas control system must control capacitor charging, machine and diagnostic timing and triggering, Marx module diagnostics, vacuum systems, gas handling for railgaps, safety interlocks, and oil handling. Many of these tasks will be performed by industrial-style programmable logic controllers (PLCs). Each of 38 Marx bank maintenance units will have a control and diagnostic package which will monitor both charging and discharging current and railgap trigger timing. An unusual feature of these Marx monitoring stations will be the inclusion of high speed digitizers to record each Marx module's output waveform, plus nanosecond resolution time interval meters to record the firing time of each railgap. The machine data acquisition system for Atlas will be built around an SQL database, use National Instruments LabVIEW software to control data acquisition instruments and provide links for a variety of experimentalists' data analysis packages. World Wide Web access will provide an interface through which users can monitor experimental data and machine status.
TL;DR: In this article, the authors describe the design of an Arkad'ev-Marx generator with the capacitors discharging energy into the magnetic field within a time less than 1 μsec.
Abstract: We describe the design of an Arkad’ev-Marx generator with the capacitors discharging energy into the magnetic field within a time less than 1 μsec. We give the equivalent circuit of the generator and calculations for the transient for different firing circuits. We present the results of an experimental study of a generator consisting of 10 stages.
29 Jun 1997
TL;DR: The DECADE generator as mentioned in this paper consists of a Marx bank, a water transfer capacitor, a passive water line, a vacuum line, and a plasma opening switch (POS), and a bremsstrahlung diode load.
Abstract: The DECADE generator consists of individual modules operated in parallel. Each module consists of a Marx bank, a water transfer capacitor, a passive water line, a vacuum line, a plasma opening switch (POS), and a bremsstrahlung diode load. Initial results from single module tests on DECADE Module 1 resulted in less radiation than originally specified. A subsequent, multi-laboratory effort demonstrated that the bremsstrahlung from this module can be increased to the levels originally specified for the multi-module system. The increased radiation was largely the result of two changes: discharge cleaning in the POS-load region with an argon-oxygen mixture (instead of pure argon), and a change in the converter package. Evidence exists for other processes that limit the radiation. If these limiting processes are circumvented, the radiation output could increase by an additional factor of two.
29 Jun 1997
TL;DR: In this paper, a series of experiments were conducted in order to establish the pulse repetition frequency (PRF) performance of a five stage spark gap column which was used to fire a five-stage PFN Marx generator.
Abstract: This paper describes a series of experiments which were undertaken in order to establish the pulse repetition frequency (PRF) performance of a five stage spark gap column which was used to fire a five stage PFN Marx generator. Spark gap columns can provide a versatile and inexpensive method of firing multi-stage generators and are an alternative to using discrete switches. Also, the geometry of a spark gap column can be designed such that closure of the spark gaps in the column results in the subsequent unclosed spark gaps being irradiated. This means that the generator in which the spark gap column is used can exhibit a very stable erection process without the requirement for external UV or electrical triggering. The parameters examined which influence the PRF were the gas pressure in the spark gap column (1-5 bar), the gas type (air, SF/sub 6/, SF/sub 6//He) and the charging time constant of the generator (0.5-1.375 ms). It has been found that SF/sub 6/ possesses a faster voltage recovery time than air, and that the addition of He to SF/sub 6/ has no significant effect on the voltage recovery time. Also, the rate of rise of the voltage across a recovering spark gap is significant in the PRF performance.