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Your search keyword '"Zweben, S. J."' showing total 404 results
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404 results on '"Zweben, S. J."'

1. ExB flows for high-throughput plasma mass separation

Author

Gueroult, R., Zweben, S. J., Fisch, N. J., and Rax, J. -M.

Subjects
Physics - Plasma Physics
Abstract

High-throughput plasma separation based on atomic mass holds the promise for offering unique solutions to a variety of high-impact societal applications. Through the mass differential effects they exhibit, crossed-field configurations can in principle be exploited in various ways to separate ions based on atomic mass. Yet, the practicality of these concepts is conditioned upon the ability to drive suitable crossed-field flows for plasma parameters compatible with high-throughput operation. Limited current predictive capabilities have not yet made it possible to confirm this possibility. Yet, past experimental results suggest that end-electrodes biasing may be effective, at least for certain electric field values. A better understanding of cross-field conductivity is needed to confirm these results and confirm the potential of crossed-field configurations for high-throughput separation., Comment: Submitted to Phys. Plasmas

Published
2018

2. On the statistics of edge fluctuations: comparative study between various fusion devices

Author

Sattin, F., Agostini, M., Scarin, P., Vianello, N., Cavazzana, R., Marrelli, L., Serianni, G., Zweben, S. J., Maqueda, R. J., Yagi, Y., Sakakita, H., Koguchi, H., Kiyama, S., Hirano, Y., and Terry, J. L.

Subjects
Physics - Plasma Physics
Abstract

In this paper we present a statistical study of edge fluctuations taken with the Gas Puffing Imaging (GPI) diagnostics. We carry out a comparison of GPI signal from an extensive database including four devices (two Tokamaks and two Reversed Field Pinches). The data are analyzed in terms of their statistical moments Skewness and Kurtosis, as done in [B. Labit, et al, Phys. Rev. Lett. \textbf{98}, 255002 (2007)]. The data align along parabolic curves, although different from machine to machine, with some spread around the best-fitting curve. A discussion about the meaning of the parabolic trend as well as the departure of real data from it is provided. A phenomenological model is finally provided, attempting to accomodate experimental evidence., Comment: To appear in Plasma Physics and Controlled Fusion

Published
2009
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6. Fusion Product Measurements in D-T Plasmas in TFTR

Author

Johnson, L. C., Barnes, C. W., Bell, R. E., Bitter, M., Budny, R. V., Bush, C. E., Darrow, D. S., Duong, H. H., Efthimion, P. C., Fisher, R. K., Fonck, R. J., Herrmann, H. W., Jassby, D. L., Krasilnikov, A. V., McKee, G. R., Medley, S. S., Osakabe, M., Petrov, M. P., Roquemore, A. L., Sasao, M., Sesnic, S., Stratton, B. C., Synakowski, E. J., von Goeler, S., Zweben, S. J., Stott, Peter E., editor, Gorini, Giuseppe, editor, and Sindoni, Elio, editor

Published
1996
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19. Blob wakes in NSTX

Author

Zweben, S. J., primary, Myra, J. R., additional, Diallo, A., additional, Russell, D. A., additional, Scotti, F., additional, and Stotler, D. P., additional

Published
2019
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31. Mean flows and blob velocities in scrape-off layer (SOLT) simulations of an L-mode discharge on Alcator C-Mod

Author

Massachusetts Institute of Technology. Plasma Science and Fusion Center, Labombard, Brian, Hughes Jr, Jerry, Terry, James L, Russell, D. A., Myra, J. R., D'Ippolito, D. A., Zweben, S. J., Massachusetts Institute of Technology. Plasma Science and Fusion Center, Labombard, Brian, Hughes Jr, Jerry, Terry, James L, Russell, D. A., Myra, J. R., D'Ippolito, D. A., and Zweben, S. J.

Abstract

Two-dimensional scrape-off layer turbulence (SOLT) code simulations are compared with an L-mode discharge on the Alcator C-Mod tokamak [Greenwald et al., Phys. Plasmas 21, 110501 (2014)]. Density and temperature profiles for the simulations were obtained by smoothly fitting Thomson scattering and mirror Langmuir probe (MLP) data from the shot. Simulations differing in turbulence intensity were obtained by varying a dissipation parameter. Mean flow profiles and density fluctuation amplitudes are consistent with those measured by MLP in the experiment and with a Fourier space diagnostic designed to measure poloidal phase velocity. Blob velocities in the simulations were determined from the correlation function for density fluctuations, as in the analysis of gas-puff-imaging (GPI) blobs in the experiment. In the simulations, it was found that larger blobs moved poloidally with the E × B flow velocity, v E , in the near-SOL, while smaller fluctuations moved with the group velocity of the dominant linear (interchange) mode, v[subscript E] + 1/2 v[subscript di] , where v [subscript di] is the ion diamagnetic drift velocity. Comparisons are made with the measured GPI correlation velocity for the discharge. The saturation mechanisms operative in the simulation of the discharge are also discussed. It is found that neither sheared flow nor pressure gradient modification can be excluded as saturation mechanisms., United States. Department of Energy. Office of Fusion Energy Sciences (Grant DE-FG02-97ER54392), United States. Department of Energy. Office of Fusion Energy Sciences (Agreement DE-FC02-99ER54512), United States. Department of Energy. Office of Fusion Energy Sciences (Contract DE-AC02-09CH11466)

Published
2018

36. Comparison of velocimetry techniques for turbulent structures in gas-puff imaging data

Author

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, White, Anne, Sierchio, Jennifer M., Terry, James L, White, Anne E., Cziegler, I., Zweben, S. J., Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Plasma Science and Fusion Center, White, Anne, Sierchio, Jennifer M., Terry, James L, White, Anne E., Cziegler, I., and Zweben, S. J.

Abstract

Recent analysis of Gas Puff Imaging (GPI) data from Alcator C-Mod found blob velocities with a modified tracking time delay estimation (TDE). These results disagree with velocity analysis performed using direct Fourier methods. In this paper, the two analysis methods are compared. The implementations of these methods are explained, and direct comparisons using the same GPI data sets are presented to highlight the discrepancies in measured velocities. In order to understand the discrepancies, we present a code that generates synthetic sequences of images that mimic features of the experimental GPI images, with user-specified input values for structure (blob) size and velocity. This allows quantitative comparison of the TDE and Fourier analysis methods, which reveals their strengths and weaknesses. We found that the methods agree for structures of any size as long as all structures move at the same velocity and disagree when there is significant nonlinear dispersion or when structures appear to move in opposite directions. Direct Fourier methods used to extract poloidal velocities give incorrect results when there is a significant radial velocity component and are subject to the barber pole effect. Tracking TDE techniques give incorrect velocity measurements when there are features moving at significantly different speeds or in different directions within the same field of view. Finally, we discuss the limitations and appropriate use of each of methods and applications to the relationship between blob size and velocity., National Science Foundation (U.S.) (1122374)

Published
2017

50. Effect of a deuterium gas puff on the edge plasma in NSTX

Author

Zweben, S J, primary, Stotler, D P, additional, Bell, R E, additional, Davis, W M, additional, Kaye, S M, additional, LeBlanc, B P, additional, Maqueda, R J, additional, Meier, E T, additional, Munsat, T, additional, Ren, Y, additional, Sabbagh, S A, additional, Sechrest, Y, additional, Smith, D R, additional, and Soukhanovskii, V, additional

Published
2014
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