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Your search keyword '"E. Nieschmidt"' showing total 4 results
Start Over Author "E. Nieschmidt" Topic condensed matter physics
4 results on '"E. Nieschmidt"'

1. Transport and stability studies on TFTR

Author

E. Nieschmidt, K. L. Wong, Cris W. Barnes, H. F. Dylla, R. J. Knize, D. Mueller, A. Miller, Hyeon K. Park, R. A. Hulse, Brentley Stratton, S. von Goeler, Gregory W. Hammett, G. Taylor, Neil Pomphrey, M. McCarthy, S. D. Scott, J.F. Schivell, R. J. Fonck, G. D. Tait, Hans-Stephan Bosch, S. J. Zweben, M. C. Zarnstorff, A. T. Ramsey, W. Stodiek, S. J. Kipatrick, N. R. Sauthoff, D. Dimock, V. Arunsalam, R. T. McCann, G. L. Schmidt, S. L. Davis, R. B. Howell, Robert James Goldston, A. Cavallo, M. G. Bell, R. Kaita, D. K. Owens, E.D. Fredrickson, J. Timberlake, J. Manickam, H. H. Towner, Robert Budny, J. Sinnis, J. E. Stevens, L. C. Johson, D. K. Mansfield, Manfred Bitter, K. P. Jaehnig, M. H. Redi, M. Ulrickson, D.L. Jassby, G. Greene, P. Colestock, H. W. Hendel, M. Williams, P. C. Efthimion, G. Schilling, R. M. Wieland, T. Saito, K. McGuire, H. Hsuan, S. Yoshikawa, F. C. Jobes, G. Kuo-Petravic, R. J. Hawryluk, S. S. Medley, N. Bretz, A.B. Ehrhardt, K. W. Hill, A. L. Roquemore, W. Morris, C. E. Bush, D. C. McCune, David W. Johnson, D. H. McNeill, Dale Meade, L. R. Grisham, Einar Hinnov, B. Grek, P. H. LaMarche, D. R. Mikkelsen, Dennis M. Manos, and K. M. Young

Subjects
Tokamak, Materials science, Atmospheric-pressure plasma, Plasma, Condensed Matter Physics, Thermal diffusivity, law.invention, Ion, Nuclear Energy and Engineering, law, Electron temperature, Neutron source, Atomic physics, Beam (structure)
Abstract

During the 1987 run, TFTR reached record values of QDD, neutron source strength, and Ti(0). Good confinement together with intense auxiliary heating has resulted in a plasma pressure greater than 3*105 Pascals on axis, which is at the ballooning stability boundary. At the same time improved diagnostics, especially ion temperature profile measurements, have led to increased understanding of tokamak confinement physics. Ion temperature profiles are much more peaked than previously thought, implying that ion thermal diffusivity, even in high ion temperature supershot plasmas, is greater than electron thermal diffusivity. Based on studies of the effect of beam orientation on plasma performance, one of the four neutral beamlines has been re-oriented from injecting co-parallel to counter parallel, which will increase the available balanced neutral injection power from 14 MW to 27 MW. With this increase in balanced beam power, and the addition of 7 MW of ICRF power it is planned to increase the present equivalant QDT of 0.25 to close to break-even conditions in the coming run.

Published
1988
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2. TFTR Initial operations

Author

D. Mikkelson, H. W. Hendel, H. F. Dylla, R.J. Hawryluk, D. McCune, P. C. Efthimion, Dale Meade, Robert James Goldston, Joseph L. Cecchi, E. Nieschmidt, J. Coonrod, M. Bell, D. Mueller, K. McGuire, R. B. Krawchuk, M. McCarthy, K.W. Hill, R. Little, G. D. Tait, J. Isaacson, Robert Kaita, L. C. Johnson, S. S. Medley, G. Taylor, L. Samuelson, D. J. Grove, N. L. Bretz, M. Ulrickson, J. Schivell, W. Blanchard, A. L. Roauemore, D.K. Owens, S. L. Davis, F. Tenney, Kenneth M. Young, J. A. Schmidt, S. Sesnic, R. J. Fonck, J. Sinnis, A. T. Ramsey, J. D. Strachan, and N. R. Sauthoff

Subjects
Physics, Hydrogen, Feedback control, chemistry.chemical_element, Plasma, Condensed Matter Physics, Nuclear physics, Nuclear Energy and Engineering, chemistry, Deuterium, Impurity, Atomic physics, Tokamak Fusion Test Reactor, Scaling, Current decay
Abstract

TSTR (Tokamak Fusion Test Reactor) has operated since December 1982 with ohmically heated plasmas. Routine operation with feedback control of plasma current, position and density has been obtained for plasmas with Ip800 kA, a = 68 cm, R = 250 cm, and Bt=27 kG. A maximum plasma current of 1 MA was achieved with q2.5. Energy confinement times of ~150 msec were measured for hydrogen and deuterium plasmas with e = 2 x 1013 cm-3, Te(0) 21.5 keV, Ti(0) = 1.5 keV and Zeff1 3. The preliminary results suqgest a size-cubed scaling from PLT, and are consistent with Alcator C scaling where T ~ nR2a. Initial measurements of plasma disruption characteristics indicate current decay rates of ~ 800 kA in 8 ms which is within the TFTR design requirement of 3 MA in 3 ms.

Published
1984
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3. Confinement of high-density pellet-fueled discharges in TFTR

Author

R. M. Wieland, M. C. Zarnstorff, M. G. Bell, Manfred Bitter, D. Mueller, G. L. Schmidt, K. W. Hill, W. W. Heidbrink, A. T. Ramsey, L. C. Johnson, R. J. Hawyrluk, E. Nieschmidt, David W. Johnson, E.D. Fredrickson, B. Grek, V. Arunasalam, G. Taylor, S. Sesnic, Hyeon K. Park, S. L. Milora, J. B. Wilgen, P. C. Efthimion, Dale Meade, B. L. Stratton, J.F. Schivell, S.K. Combs, A. C. England, H. W. Hendel, K. McGuire, Robert James Goldston, D. K. Mansfield, L. R. Grisham, C. E. Bush, D. C. McCune, P. H. LaMarche, R. Little, F. Stauffner, D. K. Owens, and H. H. Towner

Subjects
Materials science, Nuclear Energy and Engineering, Pellet, Limiter, Plasma confinement, High density, Graphite, Plasma, Penetration (firestop), Atomic physics, Condensed Matter Physics, Plasma current
Abstract

TFTR pellet injection results reported by Schmidt (1985) have been extended to higher density and n tau in plasmas limited by a graphite inner-wall belt limiter. Increased pellet penetration and larger density increases were achieved by operation at reduced plasma current (1.6 MA) and minor and major radius (70 cm and 235 cm). Under these conditions, beam heating results have been extended to 7 MW.

Published
1986
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4. TFTR confinement results

Author

P. C. Efthimion, R. J. Fonck, Joseph L. Cecchi, G. D. Tait, S. J. Zweben, S. D. Scott, E.D. Fredrickson, G. L. Schmidt, M. C. Zarnstorff, H.W. Kugel, S. Hiroe, V. Arunsalam, J. Sinnis, H. F. Dylla, Robert James Goldston, E. Nieschmidt, F. Stauffer, K. McGuire, David W. Johnson, S. L. Milora, N. Bretz, Stanley Kaye, S. Sesnic, R. M. Wieland, J. B. Wilgen, B. Grek, S. Yoshikawa, Hyeon K. Park, J. E. Simpkins, J.F. Schivell, Samuel Cohen, R. T. McCann, G. Taylor, D. Mueller, K. L. Wong, Dale Meade, R. J. Hawryluk, M. McCarthy, S. L. Davis, S. S. Medley, Einar Hinnov, R. Little, A. T. Ramsey, J. Coonrod, F.P. Boody, K. M. Young, A. C. England, Brentley Stratton, N. R. Sauthoff, R. A. Hulse, L. C. Johnson, Manfred Bitter, D. K. Owens, D. K. Mansfield, A. L. Roquemore, H.P. Eubank, M. H. Redi, M. Shimada, H. H. Towner, S.K. Combs, W. R. Blanchard, M. Ulrickson, P. H. LaMarche, D. R. Mikkelsen, W. Morris, C. E. Bush, D. C. McCune, L. R. Grisham, M. Williams, B. Prichard, S. J. Kilpatrick, Dennis M. Manos, D. Dimock, R. Kaita, J. D. Callen, H. Hsuan, S. von Goeler, W. W. Heidbrink, R. J. Colchin, H. W. Hendel, R. Kamperschroer, M. G. Bell, V. K. Pare, K. W. Hill, and Robert Budny

Subjects
Range (particle radiation), Materials science, Toroid, Pellets, Plasma, Condensed Matter Physics, Acceleration voltage, Neutral beam injection, Nuclear Energy and Engineering, Physics::Plasma Physics, Physics::Space Physics, Limiter, Atomic physics, Beam (structure)
Abstract

The characteristics of plasma operation on the axisymmetric inner toroidal limiter in TFTR are described. After conditioning, plasmas with low metal content and low zeff are obtained with this limiter. There is no substantial increase in zeff with total input power during neutral beam injection. Compared to operation on the outer blade limiter, additional gas is required to fuel plasmas on the inner limiter. Injection of D pellets increased the plasma density substantially and produced energy confinement times up to 0.5 s in ohmically heated plasmas. The four neutral beam lines have injected up to 13.5 MW total power into the plasma for 0.5 s with up to 90 kV accelerating voltage. The scaling of the plasma stored energy was studied as a function of the input power, plasma current and plasma density. In the range 1.4 to 2.2 MA, the overall and incremental confinement times for both the total and thermal stored energies increase with plasma current at fixed density. There appears to be a weak negative scaling of the total stored energy with density at high injection power.

Published
1986
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