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Your search keyword '"E. Nieschmidt"' showing total 6 results
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6 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. Experimental results from the TFTR tokamak

Author

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

Subjects
Nuclear physics, Tokamak, Materials science, Deuterium, law, Electric heating, Plasma, Atomic physics, Joule heating, Ohmic contact, Beam (structure), law.invention, Ion
Abstract

Recent experiments on TFTR have extended the operating regime of TFTR in both ohmic- and neutral-beam -heated discharges. The TFTR tokamak has reached its original machine-design specifications ( I p = 2.5 MA and B T = 5.2 T). Initial neutral-beam -heating experiments used up to 6.3 MW of deuterium beams. With the recent installation of two additional beamlines, the power has been increased up to 11 MW. A deuterium pellet injector was used to increase the central density to 2.5 x 10 20 m -3 in high-current discharges. At the opposite extreme, by operating at low plasm a current ( I p ~ 0.8 MA) and low density ( n e~ 1 x 10 19 m -3 ), high ion temperatures (9 + 2 keV) and rotation speeds (7 x 10 5 m s -1 ) have been achieved during injection. In addition, plasma-compression experiments have demonstrated acceleration of beam ions from 82 to 150 keV, in accord with expectations. The wide operating range of TFTR, together with an extensive set of diagnostics and a flexible control system, has facilitated transport and scaling studies of both ohmic- and neutral-beam -heated discharges. The result of these confinement studies are presented.

Published
1987
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3. Plasma-material interactions in TFTR

Author

P. C. Efthimion, Joseph L. Cecchi, R. Little, L. C. Johnson, G. L. Schmidt, Robert Budny, W. R. Wampler, E. Nieschmidt, P. H. LaMarche, D. R. Mikkelsen, E.D. Fredrickson, B. L. Doyle, S. J. Kilpatrick, H. F. Dylla, R. Groebner, A. C. England, M. Shimada, H. W. Hendel, F. Stauffer, B. Grek, K. W. Hill, Hyeon K. Park, Robert James Goldston, J. E. Simpkins, Team Tftr Team, Dennis M. Manos, M. H. Redi, S.K. Combs, C. E. Bush, A.E. Pontau, W. R. Blanchard, M. Ulrickson, S. Sesnic, D. K. Mansfield, David W. Johnson, M. G. Bell, D. Mueller, S. L. Davis, Dale Meade, K. Wilson, B. Prichard, K. M. Young, Brentley Stratton, S. L. Milora, G. Taylor, A. T. Ramsey, J.F. Schivell, D.B. Heifetz, K. L. Wong, N. Bretz, S. D. Scott, P. P. Boody, M. Williams, M. C. Zarnstorff, L. R. Grisham, H.P. Eubank, R. J. Fonck, O. K. Owens, R. A. Hulse, R. J. Hawryluk, S. S. Medley, M. Murakami, Samuel A. Cohen, S. Hiroe, S. von Goeler, G. D. Tait, J. Sinnis, and S. J. Zweben

Subjects
Nuclear and High Energy Physics, Materials science, chemistry.chemical_element, Plasma, Oxygen, Nuclear Energy and Engineering, chemistry, Sputtering, Getter, Impurity, Limiter, General Materials Science, Atomic physics, Carbon, Helium
Abstract

This paper presents a summary of plasma-material interactions which influence the operation of TFTR with high current (≤ 2.2 MA) ohmically heated, and high-power (∼ 10 MW) neutral-beam heated plasmas. The conditioning procedures which are applied routinely to the first-wall hardware are reviewed. Fueling characteristics during gas, pellet, and neutral-beam fueling are described. Recycling coefficients near unity are observed for most gas fueled discharges. Gas fueled discharges after helium discharge conditioning of the toroidal bumper limiter, and discharges fueled by neutral beams and pellets, show R

Published
1987
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4. 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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5. 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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6. Initial limiter and getter operation in TFTR

Author

E. Nieschmidt, J. Isaacson, George W. Taylor, R. J. Knize, D.J. Grove, J. Timberlake, C. E. Thomas, David W. Johnson, D. McCarthy, R. Hulse, J. D. Strachan, R. J. Hawryluk, Dale Meade, S. D. Scott, S. S. Medley, Manfred Bitter, R. Kaita, Stanley Kaye, D. R. Mikkelsen, S. J. Kilpatrick, J. Sinnis, W. R. Blanchard, M. Ulrickson, K. W. Hill, F. Tenney, Dennis M. Manos, P. C. Efthimion, J. Sredniawski, Joseph L. Cecchi, A. T. Ramsey, M. Murakami, S. L. Davis, N. R. Sauthoff, K. M. Young, N. Bretz, D. Dimock, J. Coonrod, K. McGuire, B. L. Doyle, A. L. Roquemore, D. Mueller, B. Grek, C. E. Bush, D. C. McCune, H. F. Dylla, S. von Goeler, J.F. Schivell, D. Heifetz, P. Stangeby, Samuel A. Cohen, Robert James Goldston, H. W. Hendel, M. G. Bell, R. Little, R. J. Fonck, L. C. Johnson, D. K. Owens, S. Sesnic, J. Kiraly, G. D. Tait, and H. H. Towner

Subjects
Nuclear and High Energy Physics, Materials science, Plasma heating, Nuclear engineering, Zirconium alloy, Alloy, Plasma, engineering.material, Nuclear Energy and Engineering, Getter, Limiter, Electric heating, engineering, General Materials Science, Joule heating
Abstract

During the recent ohmic heating experiments on TFTR, the movable limiter array, preliminary inner bumper limiter, and prototype ZrAl alloy bulk getter surface pumping system were brought into operation. This paper summarizes the operational experience and plasma characteristics obtained with these components. The near-term upgrades of these systems are also discussed.

Published
1984
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