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IEEE Transactions on Plasma Science

Issue 5 • Date Oct 1991

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Displaying Results 1 - 25 of 44
  • Experimental investigations of feedback circuits for suppressing resistive wall modes

    Publication Year: 1991, Page(s):954 - 958
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Feedback circuits have been designed and tested which reduce the component of a fluctuating magnetic field normal to a square coil. These circuits, when placed in an array covering a toroidal plasma, may be a practical alternative to a perfectly conducting shell for stabilizing resistive wall modes View full abstract»

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  • Low-loss, high-repetition-rate vacuum switching

    Publication Year: 1991, Page(s):976 - 988
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (972 KB)

    The theory and design of a trigatron-configuration vacuum switch are presented. When operated with a series saturable inductor element it functions effectively as a high-repetition-rate closing switch for pulsed power applications. This switch configuration allows one to fully exploit the advantages inherent to a vacuum switch, such as high voltage standoff, wide triggering range, potentially fast... View full abstract»

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  • Development of arc ion sources for heavy ion fusion

    Publication Year: 1991, Page(s):782 - 789
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (604 KB)

    An overview of the development of arc ion sources for heavy ion fusion is presented. Two approaches to heavy ion fusion (HIF)-the RF linac-storage ring approach and the induction linac approach-are described. RF linac schemes require low emittance and moderate current levels, because the beam is accumulated in storage rings before being focused on target. The induction linac approach requires low ... View full abstract»

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  • Vacuum breakdown on metal surfaces

    Publication Year: 1991, Page(s):690 - 696
    Cited by:  Papers (36)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (908 KB)

    The unipolar arc model is described. Experimental proof that unipolar arcing represents a discharge form which easily leads to explosive plasma formation is provided. Using a laser-produced plasma, it has been demonstrated that unipolar arcs ignite and burn on a nanosecond time scale without any external electric field being applied. Similar unipolar arc craters have been observed on the cathode s... View full abstract»

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  • Townsend-type breakdown as a criterion for high-frequency vacuum arc interruption at submillimeter gaps

    Publication Year: 1991, Page(s):767 - 771
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    In vacuum circuit breakers, multiple reignitions give rise to HF current arcing (≈500 A; ≈200 kHz). Due to the small contact distance and the very large current gradient, at every arc-current zero pressures of several tens of millibars can be expected. Very soon thereafter (≈30 ns) this gap is dielectrically stressed by the first component of the restriking voltage (≈10 MHz), originati... View full abstract»

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  • Z-pinch current enhancement by the inverse skin effect

    Publication Year: 1991, Page(s):866 - 871
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (504 KB)

    The dynamics of a linear z-pinch discharge are studied. The magnetic field distribution inside the discharge tube was measured by small magnetic probes. It was found that after the maximum contraction of the plasma column, current loops are generated in the vessel by which the pinch current is largely enhanced. This effect can be attributed to the inverse skin effect. The purpose of these... View full abstract»

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  • Optical investigation of arc spot formation on cold cathodes in air

    Publication Year: 1991, Page(s):947 - 953
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1184 KB)

    The column of a high current arc was magnetically blown against a cathode positioned perpendicularly to the arc axis. A linearly increasing voltage was applied to this electrode. It was shown by high-speed photography that the arc spot ignition is initiated by an intensified light emission on the cathode within an area of approximately 40-μm diam. SEM micrographs from the traces produced during... View full abstract»

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  • Performance improvements with advanced design foils in high-current electron beam diodes

    Publication Year: 1991, Page(s):846 - 849
    Cited by:  Papers (2)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    A design for the vacuum/pressure barrier of an electron-beam diode ready to be fielded on a large krypton-fluoride excimer laser is described. The barrier is a composite foil, fabricated from carbon fibers, Kapton-membrane, epoxy, and copper foil. This composite foil has advantages over more traditional metal foils, exhibiting particularly high tensile strength and a high modulus of elasticity. Ot... View full abstract»

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  • Relativistic beam-plasma systems in finite geometry

    Publication Year: 1991, Page(s):968 - 975
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    Some of the basic equations and physics associated with a finite-geometry, relativistic beam-plasma system in an external axially periodic magnetic field are presented. The electromagnetic eigenmodes associated with such a system are determined, the boundary conditions are discussed, and the conditions under which coupling between these modes and with plasma waves is introduced by the finite-geome... View full abstract»

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  • Initial stage of discharge current growth in a triggered vacuum gap

    Publication Year: 1991, Page(s):778 - 781
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    The dynamics of light emission accompanying the initial stage of electric discharge in a substantially undervoltaged vacuum gap was studied with a knock-down model using high-speed photorecording. Voltage across the gap was maintained within the range of 0.5-5 kV, which corresponded to the minimum operating voltage of vacuum-triggered gaps. It was found that front layers of a plasma cloud near a c... View full abstract»

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  • Vacuum discharge effects in the diodes of high-current electron accelerators

    Publication Year: 1991, Page(s):683 - 689
    Cited by:  Papers (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (608 KB)

    The processes occurring in the diodes of high-current electron accelerators which affect the electron beam structure are discussed. Two types of diodes are analyzed: planar diodes producing large cross-section beams, and magnetically insulated diodes producing cylindrical beams. The effects considered are: the screening effect, the effect of touches, the relay effect, the ring effect, etc. They ar... View full abstract»

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  • Vacuum arc ion charge-state distributions

    Publication Year: 1991, Page(s):713 - 717
    Cited by:  Papers (169)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    Vacuum arc ion charge-state spectra have been measured for a wide range of metallic cathode materials. The charge-state distributions were measured using a time-of-flight diagnostic to monitor the energetic ion beam produced by a metal vapor vacuum arc ion source. Data were obtained for 48 metallic cathode elements: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo... View full abstract»

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  • Investigation of plasma opening switch conduction and opening mechanisms

    Publication Year: 1991, Page(s):757 - 766
    Cited by:  Papers (47)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (912 KB)

    Plasma opening switch techniques have been developed for pulsed power applications to exploit the advantages of electrical energy storage in a vacuum inductor compared to conventional, capacitive-based energy storage. Experiments are described that demonstrate the successful application of these techniques in conduction time ranges from 50 ns to over 1 μs. Physics understanding of the conductio... View full abstract»

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  • The Cowling `limiting-points' proof of his anti-dynamo theorem

    Publication Year: 1991, Page(s):862 - 865
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    According to the Cowling antidynamo theorem, a self-excited steady-state dynamo in a conducting fluid cannot be axisymmetric. One of his proofs, which is based on the impossibility of the existence of limiting points, was referred to by I. Alexeff (ibid., vol.17, pp.282-283, Apr. 1989) who showed that it is not valid in diffuse plasmas. It is here shown that Cowling's limiting-points proof, which ... View full abstract»

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  • Measurement of arc spot formation delay times at cold cathodes in air

    Publication Year: 1991, Page(s):942 - 946
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    The column of a high current arc is magnetically blown against a cathode positioned perpendicularly to the arc axis. A linearly increasing voltage is applied to this electrode. The delay time of the arc spot formation which initiates the arc commutation was measured for smooth electrodes made of Cu, steel, graphite, Mg, and Ce. The cumulative frequency distribution of this delay time was found to ... View full abstract»

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  • Technological sources of charged particles with plasma emitters

    Publication Year: 1991, Page(s):743 - 745
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (208 KB)

    At present, ion and electron beams, extensively used in industry, usually have a small cross section. Presented are generators of ion and electron flows with a large cross section using plasma emitters. These devices have a wide range of currents and voltages and are designed for metallurgical treatment and microelectronics. The author discusses a technological source of ions based on the vacuum-a... View full abstract»

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  • Beam rotation and shear in a large electron beam diode

    Publication Year: 1991, Page(s):840 - 845
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1036 KB)

    The time-averaged electron-beam current distribution of one of the electron guns of the large Aperture Module (LAM) of the Aurora laser was measured as part of a larger set of experiments designed to study the electron beam transport to and energy deposition in the LAM laser chamber. The radiograms made on the center line of the LAM laser chamber while the laser chamber was at vacuum pressure demo... View full abstract»

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  • A sequential plasma focus

    Publication Year: 1991, Page(s):912 - 919
    Cited by:  Papers (51)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    Shadowgraph studies suggest that a target disk placed downstream of the anode of a plasma focus may become an auxiliary anode producing a second focusing event when the current sheet climbs over it after the first focus event. A model is put forth in which each event is assumed to comprise three phases: an axial phase, a radial phase, and a radial extension or expanded column phase. This model pro... View full abstract»

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  • Expansion of hydrogen arcs driven by oscillating currents

    Publication Year: 1991, Page(s):959 - 967
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (640 KB)

    Calculations of the arc channel radius using the arc current as the independent variable are presented and discussed. Previously reported experimental results for the expansion of ~300-A to ~3000-A discharges in 460-torr hydrogen are compared with the theoretical radius calculations presented. Errors introduced in the calculated channel radius are investigated by first assuming the channel conduct... View full abstract»

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  • Miniaturized liquid metal ion sources (MILMIS)

    Publication Year: 1991, Page(s):790 - 799
    Cited by:  Papers (5)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (948 KB)

    Introductory remarks are given on ion sources, and basic features of liquid-metal ion sources (LMISs) are outlined. A special by-product of field-emission electric space propulsion by a liquid metal ion thruster is the slit emitter, which may be qualified as a semiminiaturized LMIS. The state-of-the-art technology of field-emitter arrays common in vacuum microelectronics is presented in view of th... View full abstract»

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  • Macroscopic models of internal dynamics of electrical discharges

    Publication Year: 1991, Page(s):697 - 704
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    The existence of thresholds for electrical discharge onset suggests a functional relation between macroscopic resistivity and current. At low current, the resistivity should be inversely proportional to the magnitude of the current. Macroscopic models which employ this scaling predict many empirically observed properties of transient electrical discharges such as: (i) thresholds for the onset of c... View full abstract»

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  • An experimental investigation on high-frequency vacuum arc interruption at small gap length

    Publication Year: 1991, Page(s):772 - 777
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (368 KB)

    An experimental study of high-frequency (126, 230 kHz) vacuum arc interruption behavior and the voltage escalation processes at a small gap length (⩽1 mm) for three contact materials (Cu, CuCr, and CuTeSe) is discussed. Two experimental methods have been used: current injection in a low-voltage circuit and in a 10-kV AC circuit. Experimental results of the high-frequency current interruption a... View full abstract»

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  • Investigation of dynamics of a magnetically induced compression gas puff

    Publication Year: 1991, Page(s):872 - 878
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (568 KB)

    Dynamic parameters of a magnetically induced compression gas puff have been measured. It is shown that the injected gas in this type of gas puff is partially ionized by an internal source. The major source of ionization is shown to be the UV light emitted from inside the gas puff through the nozzle slit opening. This idea is supported by the ionic current and light output measurements at different... View full abstract»

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  • Transverse oscillations of a long-pulse electron beam on a laser-formed channel

    Publication Year: 1991, Page(s):850 - 854
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    An intense relativistic electron beam may be transported in low-pressure gas using an ion channel which focuses and guides the beam. The beam can be unstable to the growth of transverse oscillations caused by the electric force between the beam and channel-the ion hose instability. Beam propagation on channels created by photoionization of gas with an excimer laser is discussed. Ion hose oscillati... View full abstract»

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  • Influence of electrode separation on ion density in the vacuum arc

    Publication Year: 1991, Page(s):718 - 724
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (500 KB)

    The density of singly ionized chromium shortly before and after forced extinction of vacuum arcs between chromium-copper electrodes was measured by laser-induced fluorescence for 2- and 10-mm contact gaps and currents between 200 A and 1 kA. In all cases studied, the ion density was constant before ramping down to the current and decayed exponentially after current zero. The ion density at current... View full abstract»

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Aims & Scope

IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

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Meet Our Editors

Editor-in-Chief
Steven J. Gitomer, Ph.D.
Senior Scientist, US Civilian Research & Development Foundation
Guest Scientist, Los Alamos National Laboratory
1428 Miracerros Loop South
Santa Fe, NM  87505  87505  USA
tps-editor@ieee.org
Phone:505-988-5751
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