J. Bradley, J. Gahl, S. Suzuki, P. Rockett, J. Hunter
{"title":"Pulsed power diagnostics on the PLADIS I plasma gun","authors":"J. Bradley, J. Gahl, S. Suzuki, P. Rockett, J. Hunter","doi":"10.1109/PPC.1995.599726","DOIUrl":"https://doi.org/10.1109/PPC.1995.599726","url":null,"abstract":"Tokamak disruption simulation experiments are being conducted at the University of New Mexico (USA) using the PLADIS I plasma gun system. PLADIS I is a high power, high energy coaxial plasma gun configured to produce an intense plasma beam. The inductance and capacitance of the PLADIS I gun circuit are adjusted to produce a current pulse with a full width half max (FWHM) time of 100 /spl mu/s. Candidate materials are placed in the beam path to determine their response under disruption relevant energy densities. Various diagnostics have been used to determine the characteristics of the incident plasma and the vapor shielding plasma. Calorimeter arrays provided by the Japan Atomic Energy Research Institute were used to determine the profile of energy density deposited in the array material. A fast, two color optical pyrometer was used to determine the surface temperature of the sample as a function of time during initial plasma/surface interaction, before the vapor shield plasma becomes optically thick and obscures the surface. A time resolved target surface pressure diagnostic using a commercially available, fast response polyvinylidine fluoride pressure sensor has been built and is used to determine the pressure pulse of the plasma as a function of position and time. Data from this diagnostic regarding plasma beam spot size and pulse width are compared to results from other diagnostics. Initial results from the pressure diagnostic agree very well with the risetime of the surface temperature and the FWHM time of the gun current pulse. Further results regarding total absorbed energy, time resolved target surface temperature and time resolved target surface pressure in PLADIS I as a function of incident power and energy are presented.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84482838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimal simulation techniques for distributed energy store railguns with solid state switches","authors":"J. Cornette, R. Marshall","doi":"10.1109/PPC.1995.599793","DOIUrl":"https://doi.org/10.1109/PPC.1995.599793","url":null,"abstract":"The objective of this paper is to present an optimal design methodology to determine the best firing strategy, energy store sizing, energy store spacing and maximum system efficiency for a distributed energy store (DES) railgun. System simulations/designs are based on the assumption that switching of the energy storage units is accomplished using solid-state devices. Candidate semiconductor technologies are promising in relation to solving the high energy, low weight requirements of a railgun system and other pulsed power systems requiring high energy, compact switching. A simulation code has been developed and used to produce nondimensional data files that are then scaled to physical railgun values based on input parameters. Capacitive in nature with diodes to prevent negative currents and crowbar diodes to prevent voltage reversal of the capacitors. The main thrust of this simulation effort is to produce a DES design that optimizes the efficiency of the conversion of stored electrical energy to projectile kinetic energy, while also considering the abilities of near term solid-state switching devices.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79803553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Basov, A. Bastrikov, B. M. Koval'chuk, V. V. Kremnev, E. Kumpjak
{"title":"High power megavolt pulsed generator with nanosecond rise time","authors":"G. Basov, A. Bastrikov, B. M. Koval'chuk, V. V. Kremnev, E. Kumpjak","doi":"10.1109/PPC.1995.599817","DOIUrl":"https://doi.org/10.1109/PPC.1995.599817","url":null,"abstract":"A pulsed generator with a power of 0.1 TW, an amplitude of up to 2 MV and /spl sim/1.5 nsec rise time is described. A Marx generator charges a low inductive capacitor (1.8 nF) and a radial line (0.9 nF) to a voltage of /spl sim/2 MV in 200 nsec. At the peak voltage, a water switch breaks down at the center of the radial line resulting in a /spl sim/2.5 MV voltage pulse at the end of the line. This pulse propagates along the oil-insulated line. The line is connected to an oil-filled peaking switch with a metal diaphragm, which reduces the transfer capacitance of the discharge gap to 5 pF in order to match the radial line with a load being connected to the switch output. A crowbar switch may be used for operation in the short-pulse mode. A pulse with a width of up to 20 nsec has been generated on a matched load equivalent.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88371670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Chemical destruction using a pulsed corona reactor","authors":"K. Hutcherson, R. Roush, R. Brown","doi":"10.1109/PPC.1995.596472","DOIUrl":"https://doi.org/10.1109/PPC.1995.596472","url":null,"abstract":"Chemical destruction measurements for a Blumlein driven pulsed corona reactor are presented along with observed current and voltage waveforms. The input gas flow consists of 0.2 to 1.5 SLPM room temperature air with a 200 ppm toluene impurity. The PCR is operated with an applied voltage of between 12 to 30 kV at 5 to 50 Hz repetition rate. The dependence of the PCR chemical destruction on rep-rate, applied voltage and flow are reported. Apparatus to observe the relation between the emission spectra and the chemical destruction is discussed.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81714171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. L. Peterson, R. L. Bowers, C. Lebeda, W. Matuska, John F. Benage, G. Idzorek, H. Oona, J. Stokes, N. Roderick
{"title":"Comparison and analysis of 2-D simulation results with two implosion radiation experiments on the Los Alamos Pegasus I and Pegasus II capacitor banks","authors":"D. L. Peterson, R. L. Bowers, C. Lebeda, W. Matuska, John F. Benage, G. Idzorek, H. Oona, J. Stokes, N. Roderick","doi":"10.2172/102223","DOIUrl":"https://doi.org/10.2172/102223","url":null,"abstract":"Two experiments, PegI-41, conducted on the Los Alamos Pegasus I capacitor bank, and PegII-25, on the Pegasus II bank, consisted of the implosions of 13 mg (nominal), 5 cm radius, 2 cm high thin cylindrical aluminum foils resulting in soft X-ray radiation pulses from the plasma thermalizion on axis. The implosions were conducted in direct-drive (no intermediate switching) mode with peak currents of about 4 MA and 5 MA respectively, and implosion times of about 2.5 /spl mu/s and 2.0 /spl mu/s. A radiation yield of about 250 kJ was measured for PegII-25. The purpose of these experiments was to examine the physics of the implosion and relate this physics to the production of the radiation pulse and to provide detailed experimental data which could be compared with 2-D radiation-magnetohydrodynamic (RMHD) simulations. Included in the experimental diagnostic suites were Faraday rotation and dB/dt current measurements, a visible framing camera, an X-ray stripline camera, time-dependent spectroscopy, bolometers and XRD's. A comparison of the results from these experiments shows agreement with 2-D simulation results in the instability development, current, and radiation pulse data, including the pulsewidth, shape, peak power and total radiation yield as measured by bolometry. Instabilities dominate the behavior of the implosion and largely determine the properties of the resulting radiation pulse. The 2-D simulations can be seen to be an important tool in understanding the implosion physics.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89807028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Bowers, J. Brownell, H. Lee, A. Scannapieco, M. Hockaday, R. Chrien, R. Bartsch, J. Cochrane, J. Ladish, H. Oona, J. Parker, D. Platts, J. Stokes, L. Veeser, D. Sorenson, R. Walton, W. Anderson, W. Broste, R. Malone, B. Warthen
{"title":"Precision solid liner experiments on Pegasus II","authors":"R. Bowers, J. Brownell, H. Lee, A. Scannapieco, M. Hockaday, R. Chrien, R. Bartsch, J. Cochrane, J. Ladish, H. Oona, J. Parker, D. Platts, J. Stokes, L. Veeser, D. Sorenson, R. Walton, W. Anderson, W. Broste, R. Malone, B. Warthen","doi":"10.1109/PPC.1995.596743","DOIUrl":"https://doi.org/10.1109/PPC.1995.596743","url":null,"abstract":"Pulsed power systems have been used in the past to drive solid liner implosions for a variety of applications. In combination with a variety of target configurations, solid liner drivers can be used to compress working fluids, produce shock waves and study material properties in convergent geometry. The utility of such a driver depends in part on how well-characterized the drive conditions are. This, in part, requires a pulsed power system with a well-characterized current waveform and well-understood electrical parameters. At Los Alamos, the authors have developed a capacitively driven, inductive store pulsed power machine, Pegasus, which meets these needs. They have also developed an extensive suite of diagnostics which are capable of characterizing the performance of the system and of the imploding liners. Pegasus consists of a 4.3 MJ capacitor bank, with a capacitance of 850 /spl mu/f fired with a typical initial bank voltage of 90 kV or less. The bank resistance is about 0.5 m/spl Omega/, and bank plus power flow channel has a total inductance of about 24 nH. In this paper, the authors consider the theory and modeling of the first precision solid liner driver fielded on the Pegasus pulsed power facility.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90060021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modeling of graphite electrode failure in high power spark gaps","authors":"M. Wofford, M. Baker, M. Kristiansen","doi":"10.1109/PPC.1995.596814","DOIUrl":"https://doi.org/10.1109/PPC.1995.596814","url":null,"abstract":"The purpose of this research is to determine the mechanism for the abrupt failure of graphite electrodes in high power spark gaps. The occurrence of damage was initially linked to a high current rate of rise (di/dt) of the system, on the order of 10/sup 11/ A/s. Under these conditions, no electrode fracture occurred. Diagnostics and theoretical modeling are provided and testing is to continue. An indirect technique is used to measure the magnitude and duration of dynamic stress on graphite electrodes during switch operation. Different operating conditions (i.e. different currents, energies) are used to obtain relative measurements. A preliminary model of the impact force on the electrodes as a function of circuit parameters is presented, possibly with a model of the force interaction and propagation through the electrodes. The experimental results are compared with the model. The ultimate goal is to pinpoint the cause of electrode rupture and improve the performance by altering external circuit, mechanical mounting or electrode geometry.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79783305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Cuneo, P. Menge, D. L. Hanson, W. E. Fowler, M. A. Bernard, G. Ziska, A. Filuk, James E. Bailey, M. Desjarlais, T. Lockner, T. J. Nash, D. Noack, S. Slutz, Dale Welch
{"title":"Cleaning techniques for applied-b ion diodes","authors":"M. Cuneo, P. Menge, D. L. Hanson, W. E. Fowler, M. A. Bernard, G. Ziska, A. Filuk, James E. Bailey, M. Desjarlais, T. Lockner, T. J. Nash, D. Noack, S. Slutz, Dale Welch","doi":"10.1109/PPC.1995.596771","DOIUrl":"https://doi.org/10.1109/PPC.1995.596771","url":null,"abstract":"Measurements and theoretical considerations indicate that the lithium-fluoride (LiF) lithium ion source operates by electron-assisted field-desorption, and provides a pure lithium beam for 10-20 ns. Evidence on both the SABRE (1 TW) and PBFA-II (20 TW) accelerators indicates that the lithium beam is replaced by a beam of protons, and carbon resulting from electron thermal desorption of hydrocarbon surface and bulk contamination with subsequent avalanche ionization. Appearance of contaminant ions in the beam is accompanied by rapid impedance collapse, possibly resulting from loss of magnetic insulation in the rapidly expanding and ionizing neutral layer. Electrode surface and source substrate cleaning techniques are being developed on the SABRE accelerator to reduce beam contamination, plasma formation, and impedance collapse. We have increased lithium current density a factor of 3 and lithium energy a factor of 5 through a combination of in-situ surface and substrate cleaning, impermeable substrate coatings, and field profile modifications.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80786702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Akiyama, U. Katschinski, K. Murayama, S. Katsuki, S. Tsukamoto
{"title":"Repetitive pulsed power generators using an inductive energy storage system","authors":"H. Akiyama, U. Katschinski, K. Murayama, S. Katsuki, S. Tsukamoto","doi":"10.1109/PPC.1995.596498","DOIUrl":"https://doi.org/10.1109/PPC.1995.596498","url":null,"abstract":"Pulsed power generators using an inductive energy storage system are extremely compact and lightweight in comparison with those using a capacitive energy storage system. A reliable opening switch operated repetitively is necessary to realize an inductive pulsed power generator. Two kinds of repetitively operated opening switches have been developed in Kumamoto University. One is an exploding copper wire set by an automatic wire setting device, and the other is a plasma opening switch using YAG laser-produced plasma. Both switches are described.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81063601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Charge injection into solid insulators","authors":"B.T. McCuistian, L. Hatfield","doi":"10.1109/PPC.1995.599716","DOIUrl":"https://doi.org/10.1109/PPC.1995.599716","url":null,"abstract":"Electrical conduction in insulators requires the presence of charge carriers. When an insulator is stressed at high fields between two electrodes, charge injection into the bulk can occur from the cathode. This injected charge is then able to influence the insulator and affect its voltage hold-off capabilities and other electrical properties. An experimental apparatus has been constructed to study insulators stressed under high fields in a vacuum. The equivalent circuit of the experiment consists of two meshes which oscillate at different frequencies. The point-plane geometry of the electrodes and insulator appear in a mesh that oscillates at a higher frequency and much lower amplitude than the applied high voltage signal. One capacitive probe is coupled to both frequency components with the necessary voltage division ratios needed to detect both frequency components simultaneously. Separation of the two frequency components by use of Fourier transform techniques allows charge injection information to be extracted from the measured voltage waveform. A description of this method and results, including charge injection inception voltages is presented.","PeriodicalId":11163,"journal":{"name":"Digest of Technical Papers. Tenth IEEE International Pulsed Power Conference","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1995-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75550654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}