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New generation of arc and arc filament power supplies for pulsed neutral beams

Description: The new Tandem Mirror Experiment (TMX) facility at LLL requires that neutral beams operate for pulse lengths between 25 and 100 ms. The inevitable increase in cost over the present 12-ms pulse length capability dictated that a more economical alternative to the pulse forming networks and the transformer-type arc filament power supplies currently in use be found. A study of the various alternatives and design requirements revealed that battery banks are the most economical alternative. The therm… more
Date: October 3, 1977
Creator: Santamaria, G.T.
Partner: UNT Libraries Government Documents Department
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Metal vapor vacuum arc (MEVVA) high current ion source

Description: An ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ions are extracted. Beams of a variety of ions have been produced, ranging from lithium up to uranium. At an extraction voltage of 25 kV we've measured an ion beam current of over 1 Ampere, with over 550 ema of the beam in an emittance of 0.07..pi.. cm. mradians (normalized). The ion charge state distribution varies with cathode material and with arc power; for uranium a typical distribution… more
Date: May 1, 1985
Creator: Brown, I.G.
Partner: UNT Libraries Government Documents Department
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Sustaining neutral beam power supply system for the Mirror Fusion Test Facility

Description: In late August 1978, a fixed price procurement contract for $25,000,000 was awarded to Aydin Energy Division, Palo Alto, California, for the design, manufacture, installation and acceptance testing of the Lawrence Livermore National Laboratory Mirror Fusion Test Facility (MFTF) Sustaining Neutral Beam Power Supply System (SNBPSS). This system of 24 power supply sets will provide the conditioned power for the 24 neutral beam source modules. Each set will provide the accel potential the arc power… more
Date: January 1, 1980
Creator: Eckard, R. D.; Wilson, J. H. & Van Ness, H. W.
Partner: UNT Libraries Government Documents Department
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The SRS (Segmented Rail Surface) railgun: A new approach to restrike control. [Segmented rail surface]

Description: A Segmented Rail Surface (SRS) structure is described that eliminates restrike arcs by progressively disconnecting segments of the rail surface after the plasma armature has passed. This technique has been demonstrated using the Los Alamos MIDI-2 railgun. Restrike was eliminated in a plasma armature acceleration experiment using metal-foil fuses as opening switches. A plasma velocity increase from 11 to 16 km/s was demonstrated using the SRS technique to eliminate the viscous drag losses associ… more
Date: January 1, 1988
Creator: J.V., Parker
Partner: UNT Libraries Government Documents Department
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DuoPIGatron ion sources for PLT injectors

Description: Plasma heating requirements for the Princeton Large Torus (PLT) are set at about 1 MJ total beam energy for 3 MW beam power of energetic hydrogen (or deuterium) neutrals at 40 keV. To fulfill this design goal from four neutral beam injectors, the duoPlGatron ion source originally developed at ORNL has been modified, developed, and scaled-up to versions with 20-cm and/or 22-cm grid diameters. Utilizing the multipole line cusp magnetic field confinement for the ionizing electrons and created Phil… more
Date: January 1, 1977
Creator: Tsai, C. C.; Stirling, W. L.; Haselton, H. H.; Davis, R. C. & Schechter, D. E.
Partner: UNT Libraries Government Documents Department
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Neutral-beam plasma source metal-arc protection circuit

Description: Neutral beam sources occasionally suffer from metal arcs inside the plasma chamber. This arcing can cause serious damage when it is sustained. Experience has shown that arcing for less than 10 msec is tolerable. This paper describes an electronic circuit designed to detect such an arc (or cathode spot) and generate a signal which can be used to turn off the source arc current and the accel voltage. One principle of spot recognition is based on the detection of abnormal, fast fluctuations in a L… more
Date: October 1, 1981
Creator: deVries, G. J.; Hopkins, D. B.; Lietzke, A. F. & Owren, H. M.
Partner: UNT Libraries Government Documents Department
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Initial testing of coated limiters in ISX-B

Description: Low-Z coatings on graphite substrates have been developed for testing as limiters in the Impurity Study Experiment (ISX-B) tokamak. Laboratory and tokamak testings have been accomplished. The laboratory tests included thermal shock experiments by means of pulsed e-beam irradiation, arcing experiments, and hydrogen and xenon ion erosion experiments. The tokamak testing consisted of ohmically heated plasma exposures with energy depositions up to 10 kJ/discharge on the limiters. The coatings, appl… more
Date: January 1, 1980
Creator: Langley, R. A.; Emerson, L. C.; Whitley, J. B. & Mullendore, A. W.
Partner: UNT Libraries Government Documents Department
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Testing of low Z coated limiters in tokamak fusion devices

Description: Extensive testing on a laboratory scale has been used to select those coatings most suitable for this environment. From this testing which included pulsed electron beam heating, low energy ion bombardment and arcing, chemical vapor deposited coating of TiB/sub 2/ and TiC on Poco graphite substrates have been selected and tested as limiters in ISX. Both limiter materials gave clean, stable, reproducible tokamak discharges the first day of operation. After one weeks exposure, the TiC limiter show… more
Date: January 1, 1980
Creator: Whitely, J. B.; Mullendore, A. W. & Langley, R. A.
Partner: UNT Libraries Government Documents Department
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Safety of superconducting fusion magnets: twelve problem areas

Description: Twelve problem areas of superconducting magnets for fusion reaction are described. These are: Quench Detection and Energy Dump, Stationary Normal Region of Conductor, Current Leads, Electrical Arcing, Electrical Shorts, Conductor Joints, Forces from Unequal Currents, Eddy Current Effects, Cryostat Rupture, Vacuum Failure, Fringing Field and Instrumentation for Safety. Priorities among these areas are suggested.
Date: January 1, 1979
Creator: Turner, L. R.
Partner: UNT Libraries Government Documents Department
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Development of a high-energy crowbar for the Los Alamos free-electron laser

Description: A 135-kV, 2.5-..mu..s crowbar has been developed to protect the TH2095A klystrons used on the Los Alamos free-electron laser. The klystron power supply consists of a 135-kV, 8.75-..mu..F capacitor bank with a stored energy of approximately 80 kJ. The TH2095A specifications require that the dissipated energy in a klystron arc be limited to less than 10J. The crowbar design is based upon a series stack of pressurized spark gaps immersed in an oil tank. The spark gaps are triggered by an SCR-switc… more
Date: January 1, 1987
Creator: Hornkohl, J. O. & Lynch, M. T.
Partner: UNT Libraries Government Documents Department
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Arcing phenomena in fusion devices workshop

Description: The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientis… more
Date: January 1, 1979
Creator: Clausing, R.E.
Partner: UNT Libraries Government Documents Department
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Observations of arcing in the ISX tokamak

Description: Results of arcing measurements on ISX stainless steel and graphite limiters, on stainless steel and Al probes, and on parts of the first wall are presented. (MOW)
Date: September 1, 1981
Creator: Mioduszewski, P.
Partner: UNT Libraries Government Documents Department
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Prospects for generating 1-10 TPa pressures with a railgun

Description: It has been demonstrated that a plasma arc can be accelerated along two current carrying parallel rails and used to accelerate a projectile. We have performed an extensive analysis and found the task of using a railgun to accelerate an impactor plate to velocities of 10 to 40 km/s to be feasible with contemporary technology. This range of impact velocities would enable shock pressures of 1 to 10 TPa to be generated for EOS research.
Date: July 13, 1979
Creator: Hawke, R. S. & Scudder, J. K.
Partner: UNT Libraries Government Documents Department
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Electromagnetic effects of plasma disruptions in tokamaks

Description: The tokamak is modeled as typically 100 mutually-coupled toroidal circuits. The self and mutual inductances and the currents and voltages are calculated. Using the calculated currents, the poloidal magnetic field and the electromagnetic forces as functions of space and time are calculated. The major conclusion of the analysis is that the torus sectors should be electrically connected to each other near the plasma. Such connections reduce the structural loads, eliminate arcing, and reduce the in… more
Date: January 1, 1981
Creator: Thomson, S. L.; Murray, J. G. & Bronner, G.
Partner: UNT Libraries Government Documents Department
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Lawrence Berkeley laboratory neutral-beam engineering test facility power-supply system

Description: The Lawrence Berkeley Laboratory is upgrading the neutral beam source test facility (NBSTF) into a neutral beam engineering test facility (NBETF) with increased capabilities for the development of neutral beam systems. The NBETF will have an accel power supply capable of 170 kV, 70 A, 30 sec pulse length, 10% duty cycle; and the auxiliary power supplies required for the sources. This paper describes the major components, their ratings and capabilities, and the flexibility designed to accomodate… more
Date: October 1, 1981
Creator: Lutz, I. C.; Arthur, C. A.; deVries, G. J. & Owren, H. M.
Partner: UNT Libraries Government Documents Department
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Control of a high-power neutral beam generator by means of arc-current regulation

Description: Preliminary tests of a method for regulating the accelerator perveance of a high-power neutral beam, by controlling the plasma source have been conducted and are encouraging. The phase shifts and feedback paths were identified and quantified, and stabilization was achieved by adding an R-C snubber at the accelerator power supply output which reduced the destabilizing phase lags. The incorporation of such regulators into future systems is envisioned to make these high-power neutral beam systems … more
Date: October 1, 1981
Creator: Lietzke, A.F. & deVries, G.J.
Partner: UNT Libraries Government Documents Department
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Observations of arcing in the ISX tokamak

Description: Arcing has been proposed as a major source of metal impurities in tokamak plasmas. Arc tracks have been observed in the ISX tokamak on the limiter, the inner-wall surface, and on the samples from the surface analysis station. Linear as well as fern-like arc tracks have been observed. From optical and SEM analysis of the tracks, it was estimated that about 10/sup 16/ to 10/sup 17/ atoms were released per arc. To study the influence of arcing on the tokamak discharge, an experiment was set up to … more
Date: January 1, 1979
Creator: Mioduszewski, P.; Clausing, R.E. & Heatherly, L.
Partner: UNT Libraries Government Documents Department
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Lawrence Berkeley Laboratory power supply system for neutral beam source development

Description: The Lawrence Berkeley Laboratory has developed and constructed a 20-kV, 20-A test facility for the development of multi-megawatt neutral atomic beam sources. This facility has been in service for approximately two years and routinely operated at 120-kV, 20-A, 0.5-sec pulses since April 1977. The accelerator power supply system consists of four 50-kV, 20-A, 0.5-sec power modules which may be connected in a variety of series and parallel combinations. The primaries are controlled with ignitron co… more
Date: October 1, 1977
Creator: Owren, H. M.; Baker, W. R.; Hopkins, D. B. & Acker, R. C.
Partner: UNT Libraries Government Documents Department
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Elimination of output-current transients in the MFTF sustaining neutral-beam-arc power supplies

Description: The twenty-three (23) MFTF sustaining neutral beam arc power supplies were designed to provide 0.3 to 30 second output pulses over a range of 24 to 71 volts and 600 to 4000 amperes at 10 percent duty. For economic reasons, the circuit design consists of a 12 pulse rectifier which is asynchronously switched on and off by a three phase electromechanical contactor in the primary ac input. The paper describes the analysis of the problem, various possible solutions considered, and the simple and ine… more
Date: October 20, 1981
Creator: Van Ness, H. W.; Mayhall, D. J. & Wilson, J. H.
Partner: UNT Libraries Government Documents Department
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Arc current modulator for neutral beam source

Description: The design of an arc current modulator for a 10 x 40 cm neutral beam source is described. The arc modulator has been designed for the TFTR Neutral Beam Source Test Facility. The purpose of the arc modulator is twofold; first, the arc modulator shapes the current rise during the turn on time of the source arc current so that good beam optics are maintained throughout the rise; second, the arc modulator has the capability of regulating the arc current to compensate for power supply ripple and oth… more
Date: November 1, 1979
Creator: DeVries, G. J.; Arthur, A. A.; Baker, W. R.; Fong, E.; Franck, J. V. & Hopkins, D. B.
Partner: UNT Libraries Government Documents Department
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Early counterpulse technique applied to vacuum interrupters

Description: Interruption of dc currents using counterpulse techniques is investigated with vacuum interrupters and a novel approach in which the counterpulse is applied before contact separation. Important increases have been achieved in this way in the maximum interruptible current and large reductions in contact erosion. The factors establishing these new limits are presented and ways are discussed to make further improvements to the maximum interruptible current.
Date: January 1, 1979
Creator: Warren, R.W.
Partner: UNT Libraries Government Documents Department
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Fiber-optic high voltage isolation of CAMAC highway

Description: Fault analyses of the Doublet III Machine predict that a worst-case 30 kV might accidentally appear on control and data acquisition wiring connected to CAMAC interface systems. Such an accident could cause damage in CAMAC and computer equipment as distant as the control room, with attendant possibility of personal injury to operators and experimenters. Protection for control room personnel and equipment has been provided in the form of fiber-optic data link systems installed in CAMAC parallel b… more
Date: November 1, 1979
Creator: Lee, S. T. & Moore, C. D.
Partner: UNT Libraries Government Documents Department
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dc arc interruption in pressurized gasses

Description: The purpose of the study was to investigate the possibility of achieving (1) short interruption time and (2) minimum contact erosion in a dc circuit interrupter. Arc interruption tests were performed on a 100-A, 600-V dc contactor under atmospheres of argon dry air, nitrogen, helium and hydrogen, each at four pressures 0.17, 0.34, 0.52, and 0.69 MPa (25, 50, 75 and 100 psig). It was found that the average arcing time in helium and hydrogen was the shortest, and that in argon the longest for the… more
Date: January 1, 1980
Creator: Chowdhuri,P.
Partner: UNT Libraries Government Documents Department
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Breakdown processes in large-area cold-cathode vacuum triodes

Description: Preionization of large-aperture high-pressure discharge-pumped gas lasers requires uniform 250 to 500 keV 10 to 100 mA cm/sup -2/ electron beams of typically 1 to 10 x 10/sup 3/ cm/sup 2/ in area. Impedance collapse due to cathode plasma expansion renders diode electron guns inefficient in this application. Introduction of a control grid limits gun current to low, controllable values until plasma closure of the cathode-grid gap occurs. However, field enhancement at the grid can cause cathode-gr… more
Date: January 1, 1984
Creator: Gibson, R.B.
Partner: UNT Libraries Government Documents Department
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