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  • 1
    Electronic Resource
    Electronic Resource
    Experimentally determined profiles of fast wave current drive in a tokamak (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2846-2848 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Profiles of the noninductive current, driven by direct electron absorption of fast waves in the ion cyclotron range of frequencies, have been determined for DIII-D tokamak discharges [Luxon et al., Plasma Physics and Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159]. The results clearly indicate the presence of centrally peaked driven current and validate theoretical models of fast wave current drive. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871643
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  • 2
    Electronic Resource
    Electronic Resource
    Fast wave propagation studies in the DIII-D tokamak (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2306-2315 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fast Alfvén waves radiated from the phased array antenna in the DIII-D tokamak [L. G. Davis et al. in Proceedings of the 12th IEEE Symposium on Fusion Engineering, Piscataway, 1987 (Institute of Electrical and Electronics Engineers, New York, 1987), p. 991] and used for heating and current drive are studied by employing a B(overdot)-loop array mounted on the vacuum vessel wall. The wave propagation direction controlled by the antenna phasing is clearly observed. A small divergence of the rays arising from the anisotropic nature of the fast wave is found. Comparison with a ray tracing code confirms that the ray position calculated by the code is precise up to at least one toroidal turn of the rays. Conservation of ktR, which is a basic assumption in computer codes, is tested. Although the upshift of toroidal wave number kt at small major radius R is confirmed, ktR is not well conserved. The so-called "eigenmode'' is observed and the cause is identified. A mass density interferometer is demonstrated by employing the extraordinary fast wave. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871913
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  • 3
    Electronic Resource
    Electronic Resource
    Nondimensional transport scaling in DIII-D: Bohm versus gyro-Bohm resolved (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 2342-2348 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The scaling of cross-field heat transport with relative gyroradius ρ* was measured in low (L) and high (H) mode tokamak plasmas using the technique of dimensionally similar discharges. The relative gyroradius scalings of the electron and ion thermal diffusivities were determined separately using a two-fluid transport analysis. For L-mode plasmas, the electron diffusivity scaled as χe∝χBρ1.1±0.3* (gyro-Bohm-like) while the ion diffusivity scaled as χi∝χBρ−0.5±0.3* (worse than Bohm-like). The results were independent of the method of auxiliary heating (radio frequency or neutral beam). Since the electron and ion fluids had different gyroradius scalings, the effective diffusivity and global confinement time scalings were found to vary from gyro-Bohm-like to Bohm-like depending upon whether the electron or ion channel dominated the heat flux. This last property can explain the previously disparate results with dimensionally similar discharges on different fusion experiments that have been published. Experiments in H mode were also done with the expected values of beta, collisionality, safety factor, and plasma shape for thermonuclear ignition experiments. For these dimensionally similar discharges, both the electron and ion diffusivities scaled gyro-Bohm-like, χe, χi∝χBρ*, as did the global thermal confinement time. This leads to a very favorable prediction for the confinement time of future ignition devices. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871259
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  • 4
    Electronic Resource
    Electronic Resource
    Electron heat transport in improved confinement discharges in DIII-D : The 40th annual meeting of the division of plasma physics of the american physical society (1999)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 6 (1999), S. 1978-1984 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)] tokamak plasmas with an internal transport barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for electron thermal transport within the plasma. Within a limited region just inside the ITB, the electron temperature gradient (ETG) modes appear to control the electron temperature gradient and, consequently, the electron thermal transport. The increase in the electron temperaturegradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the Te profile flattens and the ETG modes are predicted to be stable. With additional core electron heating, FIR scattering measurements near the axis show the presence of high k fluctuations (12 cm−1), rotating in the electron diamagnetic drift direction. This turbulence could impact electron transport and possibly also ion transport. Thermal diffusivities for electrons, and to a lesser degree ions, increase. The ETG mode can exist at this wave number, but it is computed to be robustly stable near the axis. Consequently, in the plasmas we have examined, calculations of drift wave linear stability do not explain the observed transport near the axis in plasmas with or without additional electron heating, and there are probably other processes controling transport in this region. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873494
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  • 5
    Electronic Resource
    Electronic Resource
    Soliton generation at 10 MW level in the very high frequency band (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 986-987 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Eletromagnetic solitions at a 10 MW level in a frequency band of several hundred megahertz are generated in a transmission line loaded by a nonlinear ceramic dielectric in the para- electric phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104464
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  • 6
    Electronic Resource
    Electronic Resource
    Electrostrictions in high-power soliton generator (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4717-4719 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electrostriction effects are considered in a high power dielectric loaded transmission line designed to generate solitons. The Cerenkov emission of elastic waves from the metal-dielectric interface produces the largest strain among the strain producing mechanisms. The expression for strain as a function of electric field strength is found. The signal loss due to the emission of elastic waves is shown to be insignificant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342481
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  • 7
    Electronic Resource
    Electronic Resource
    High-power soliton generation at microwave frequencies (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3277-3281 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We point out that the creation of a soliton pulse train in a nonlinear-dispersive system can be used for the generation of high-power microwave bursts. A modulated transmission line with an appropriate nonlinear dielectric is proposed. The nonlinear wave evolution is analyzed and requirements for the dielectric material are found. Problems associated with the material are discussed. Low-power experimental demonstrations of these concepts are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341517
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  • 8
    Electronic Resource
    Electronic Resource
    A method to measure magnetic field perturbations in plasma devices (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2883-2887 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Magnetic field perturbations with specific spatial geometry can be detected in the presence of a large magnetic field "background'' using printed circuit pickup coils which have the advantages of large effective area, near dc frequency response, precise geometry, thin profile, and low cost. The design and construction techniques to produce these coils are presented. A printed circuit coil has been used to detect the magnetic field from the perturbed plasma current distribution in the TEXT tokamak due to current in an external helical (m=7,n=3) winding. The measured sensitivity of this coil, ΔBcoil/Btotal, is ∼3×10−6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140622
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  • 9
    Electronic Resource
    Electronic Resource
    Plasma mass density, species mix, and fluctuation diagnostics using a fast Alfvén wave : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 478-479 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We propose use of a fast Alfvén wave interferometer and reflectometer as a tokamak diagnostic to measure the plasma mass density, D–T species mix profile, and density fluctuations. Utilizing the property that the phase velocity of the fast wave propagating across the magnetic field is the Alfvén speed with thermal correction, this fast wave interferometer on the DIII-D tokamak was successfully used to obtain the line integrated density. Since the position of the ion–ion hybrid cutoff in tokamaks is uniquely determined by the species mix ratio and wave frequency, the reflectometer arrangement finds the species mix profile. The inversion method of reflectometry is discussed. The multiple chord interferometer also measures the mass density fluctuation profile. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147610
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  • 10
    Electronic Resource
    Electronic Resource
    Diagnostic instrument for the measurement of poloidal magnetic fields in tokamaks (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1552-1556 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A diagnostic system has been developed to measure the direction of the local magnetic field within the plasma of a tokamak by making use of Zeeman splitting in an injected neutral lithium beam. A linearly polarized dye laser is used to pump the π component of the 2S-2P resonant transition. The laser polarization is rotated at a fixed frequency, and phase analysis of the subsequent fluorescence identifies the local field direction. The instrument can monitor many radial points within the plasma simultaneously, allowing a current density profile to be determined on a single shot basis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138583
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