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  • 1
    Electronic Resource
    Electronic Resource
    Central electron temperature enhancements due to sawtooth stabilization during counter electron cyclotron current drive in Tokamak à Configuration Variable (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 2909-2914 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the Tokamak à Configuration Variable (TCV), the central electron temperature obtained in discharges with counter (CNTR) electron cyclotron current drive (ECCD) is larger than with CO-ECCD or electron cyclotron resonance heating (ECRH) alone. Comparison of experimental results with calculations by the transport code PRETOR [IAEA Technical Conference on Advances in Simulation and Models of Thermonuclear Plasmas. Montreal 142 (International Atomic Energy Agency, Vienna 1992)] indicates that sawtooth stabilization is responsible for the increased confinement time and the attendant twofold enhancement of the central temperature. Sawtooth stabilization is caused in turn by the central safety factor q0 rising above 1 for CNTR-ECCD; by contrast, the simulation results show that q0〈1 in the sawtoothing CO-ECCD and ECRH cases. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874141
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  • 2
    Electronic Resource
    Electronic Resource
    Steady-state fully noninductive operation with electron cyclotron current drive and current profile control in the tokamak à configuration variable (TCV) : The 42nd annual meeting of the division of plasma physics of the American Physical Society and the 10th international congress on plasma physics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 2199-2207 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fully noninductive, steady-state electron cyclotron current drive (ECCD) has been demonstrated for the first time in experiments carried out in the tokamak à configuration variable (TCV) [O. Sauter et al., Phys. Rev. Lett. 84, 3322 (2000)]. By appropriately distributing six 0.45 MW ECCD sources over the discharge cross section, fully noninductive, stable, and stationary plasmas with Ip up to 210 kA were obtained for the full discharge duration of 1.9 s, corresponding to more than 900 energy confinement times and more than 10 current redistribution times at an average current drive efficiency η20CD=0.01[1020 A W−1 m−2]. These experiments have also demonstrated for the first time the steady recharging of the ohmic transformer using ECCD only. The effect of localized off-axis electron cyclotron heating (ECH) and EC current drive (ECCD) (co- and counter-) is investigated showing that locally driven currents amounting to only 1% of Ip significantly alter sawtooth periods and crash amplitudes. An improved quasi-stationary core confinement regime, with little or no sawtooth activity, has been obtained by a combination of off-axis ECH and on-axis CNTR–ECCD. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1355317
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  • 3
    Electronic Resource
    Electronic Resource
    Electron acceleration by plasma waves in a nonuniform plasma (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 3600-3607 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-energy electrons in plasmas have been attributed to various causes including trapping by electron plasma waves created by stimulated Raman scattering. A theory based on the acceleration of trapped electrons by such electron plasma waves as they propagate in the presence of a density gradient away from the region where they are created is presented. Results of a simple model and a wave–particle simulation consistent with experimental results are included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866441
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  • 4
    Electronic Resource
    Electronic Resource
    Formation and steady-state maintenance of field reversed configuration using rotating magnetic field current drive (2002)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 9 (2002), S. 185-200 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Rotating magnetic fields (RMF) have been used to both form and maintain field reversed configurations (FRC) in quasisteady state. These experiments differ from steady-state rotamaks in that the FRCs are similar to those formed in theta-pinch devices, that is elongated and confined inside a flux conserver. The RMF creates an FRC by driving an azimuthal current which reverses an initial positive bias field. The FRC then expands radially, compressing the initial axial bias flux and raising the plasma density, until a balance is reached between the RMF drive force and the electron–ion friction. This generally results in a very high ratio of separatrix to flux conserver radius. The achievable final conditions are compared with simple analytic models to estimate the effective plasma resistivity. The RMF torque on the electrons is quickly transferred to the ions, but ion spin-up is limited in these low density experiments, presumably by ion-neutral friction, and does not influence the basic current drive process. However, the ion rotation can result in a rotating n=2 distortion if the separatrix radius is too far removed from the plasma tube wall. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1426102
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  • 5
    Electronic Resource
    Electronic Resource
    Toroidal field generation and magnetic field relaxation in a conical-theta-pinch-generated configuration (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 561-573 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The configurations generated by conical theta pinches (CθP's) of angles 10° and 18° were studied experimentally. The hydrogen plasma density and temperature were approximately 1–3×1015 cm−3 and 5 eV, respectively. The magnetic field structure was measured by four three-dimensional magnetic probes. The magnetic helicity and energy of the configuration were calculated directly from the measured magnetic field through algorithms that were independent of the chosen coordinate and configuration axis. The magnetic fluxes were calculated after the axis was located. Single-fluid model equations predict that the toroidal field can be generated by effects that are normally neglected in the simple Ohm's law, of which the Hall effect is the most important. The average toroidal field generation was measured to vary quadratically with the cone angle of the CθP, and this field could be accounted for by the Hall effect alone. The time histories of the magnetic helicity and energy decay and poloidal to toroidal flux conversion indicated that the relaxation of the configuration had occurred in agreement with the Taylor hypothesis. The relaxation time history indicated that the relaxation behaved like a turbulent relaxation process. Therefore a spheromaklike configuration could either be generated directly by the CθP (if the generated toroidal and poloidal field had an appropriate distribution) or through relaxation (if only small amount of toroidal field was generated).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859293
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  • 6
    Electronic Resource
    Electronic Resource
    Generation of poloidally rotating spheromaks by the conical theta pinch (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 2561-2568 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spatially resolved spectroscopic measurements revealed the existence of poloidal vortex motion in spheromaks produced in a conical theta pinch. The poloidal velocity on the axis was estimated to be 5 cm/μsec. Large Doppler broadening, which previously was inferred as high ion temperature, is attributed to large internal fluid velocity. A possible effect of the vortex motion in a spheromak merging experiment is studied and found to enhance the fusion reaction rate as a finite temperature beam collider.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866094
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  • 7
    Electronic Resource
    Electronic Resource
    A Thomson scattering diagnostic for measurements in the divertor region of TCV : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 768-771 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For future divertor studies on TCV measurements of electron temperature and density and their spatial gradients along open flux surfaces will be of major interest. A Thomson scattering system is proposed for this purpose, which takes advantage of the good access via horizontal ports on three vertical levels. The modular design of the existing Thomson scattering diagnostic on TCV offers the possibility to modify it for simultaneous measurements in the main plasma and in the divertor region using the same laser. Arranging for a second passage of the laser beam at a radial position shifted towards the inside, measurements can be made along the open flux surfaces between the X point and the outer divertor strike point. The optical system is designed to share the camera lens with the existing system. After installation of additional fiber bundles and another set of filter spectrometers, the system will be capable of measuring temperature and density at ten selected locations in the divertor zone with a resolution in the vertical direction of 15 mm. Using numerical simulations, a set of interference filters has been selected to cover the range from 100 to 5 eV. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149497
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  • 8
    Electronic Resource
    Electronic Resource
    A double discharge high power TEA CO2 laser (1973)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 24 (1973), S. 439-442 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Résumé Le comportement d'un laser CO2TEA à deux décharges est étudié. Il délivre des impulsions de lumière polarisée d'une énergie de 14 Joules et durant 25 ns. L'influence de la composition du mélange gazeux sur des phénomènes tels que l'arcage, le dálai entre le pompage et l'émission lumineuse ainsi que sur la forme de l'impulsion, a été étudiée. L'introduction de 0.1% de xylène dans le mélange gazeux a permis de dissiper une énergie de 200 Joules par litre de décharge sans produire d'arc. Le rendement maximum a été de 6.5%.
    Notes: Abstract A double discharge TEA CO2 laser of simple design has been tested. The linearly polarized beam delivers a total energy of 14 Joules in 25 ns. The influence of the different gas mixtures on the problem of arcing, delay between pumping and lasing, and evolution of the light pulse, has been investigated. Using 0.1% xylene in the gas mixture, 200 Joules per liter were fed in the glow discharge without arcing. The maximum efficiency is 6.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01595210
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  • 9
    Electronic Resource
    Electronic Resource
    Laser scattering measurements on a deuterium plasma in the rotating magnetic field pinch (1974)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 25 (1974), S. 717-725 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Elektronentemperatur und Elektronendichte wurden im ”Rotating magnetic field pinch”—Experiment mit Hilfe von Laser-Licht Streuung gemessen. Die Resultate werden mit früheren Messungen und mit numerischen Berechnungen verglichen. Für die numerischen Berechnungen wurde ein magnetohydrodynamisches Dreiflüssigkeitsmodell verwendet. Der Vergleich zwischen Theorie und Experiment zeigt, dass die Wände des Entladungsrohres eine Plasmaquelle darstellen, die etwa 0.6*1015 Elektronen und ebensoviele Ionen pro cm2 pro μs erzeugt.
    Notes: Summary Electron temperature and density were measured in the rotating magnetic field pinch by means of laser light scattering. The results are compared with previous measurements and with numerical calculations based on a three-fluid magnetohydrodynamic model. The comparison between theory and experiment shows that the interior surface of the discharge tube acts as a plasma source producing approximately 0.6*1015 electron-ion pairs per cm2 per μs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01590257
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  • 10
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    Influence of Plasma Shape on Transport in the TCV Tokamak (1997)
    American Physical Society
    Details
    Publication Date: 1997-09-15
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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