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Your search keyword '"Pomphrey, N."' showing total 15 results
Start Over Author "Pomphrey, N." Journal physics of plasmas
15 results on '"Pomphrey, N."'

5. Recent advances in the design of quasiaxisymmetric stellarator plasma configurations

Author

Reiman, A., primary, Ku, L., additional, Monticello, D., additional, Hirshman, S., additional, Hudson, S., additional, Kessel, C., additional, Lazarus, E., additional, Mikkelsen, D., additional, Zarnstorff, M., additional, Berry, L. A., additional, Boozer, A., additional, Brooks, A., additional, Cooper, W. A., additional, Drevlak, M., additional, Fredrickson, E., additional, Fu, G., additional, Goldston, R., additional, Hatcher, R., additional, Isaev, M., additional, Jun, C., additional, Knowlton, S., additional, Lewandowski, J., additional, Lin, Z., additional, Lyon, J. F., additional, Merkel, P., additional, Mikhailov, M., additional, Miner, W., additional, Mynick, H., additional, Neilson, G., additional, Nelson, B. E., additional, Nührenberg, C., additional, Pomphrey, N., additional, Redi, M., additional, Reiersen, W., additional, Rutherford, P., additional, Sanchez, R., additional, Schmidt, J., additional, Spong, D., additional, Strickler, D., additional, Subbotin, A., additional, Valanju, P., additional, and White, R., additional

Published
2001
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7. Physics issues in the design of high-beta, low-aspect-ratio stellarator experiments

Author

Neilson, G. H., primary, Reiman, A. H., additional, Zarnstorff, M. C., additional, Brooks, A., additional, Fu, G.-Y., additional, Goldston, R. J., additional, Ku, L.-P., additional, Lin, Z., additional, Majeski, R., additional, Monticello, D. A., additional, Mynick, H., additional, Pomphrey, N., additional, Redi, M. H., additional, Reiersen, W. T., additional, Schmidt, J. A., additional, Hirshman, S. P., additional, Lyon, J. F., additional, Berry, L. A., additional, Nelson, B. E., additional, Sanchez, R., additional, Spong, D. A., additional, Boozer, A. H., additional, Miner, W. H., additional, Valanju, P. M., additional, Cooper, W. A., additional, Drevlak, M., additional, Merkel, P., additional, and Nuehrenberg, C., additional

Published
2000
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8. Physics of compact stellarators

Author

Hirshman, S. P., primary, Spong, D. A., additional, Whitson, J. C., additional, Nelson, B., additional, Batchelor, D. B., additional, Lyon, J. F., additional, Sanchez, R., additional, Brooks, A., additional, Y.-Fu, G., additional, Goldston, R. J., additional, Ku, L-P., additional, Monticello, D. A., additional, Mynick, H., additional, Neilson, G. H., additional, Pomphrey, N., additional, Redi, M., additional, Reiersen, W., additional, Reiman, A. H., additional, Schmidt, J., additional, White, R., additional, Zarnstorff, M. C., additional, Miner, W. H., additional, Valanju, P. M., additional, and Boozer, A., additional

Published
1999
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13. Three-dimensional equilibria and transport in RFX-mod: A description using stellarator tools.

Author

Gobbin, M., Bonfiglio, D., Boozer, A. H., Cooper, A. W., Escande, D. F., Hirshman, S. P., Lore, J., Lorenzini, R., Marrelli, L., Martin, P., Martines, E., Momo, B., Pomphrey, N., Predebon, I., Puiatti, M. E., Sanchez, R., Spizzo, G., Spong, D. A., and Terranova, D.

Subjects
PLASMA diffusion, STELLARATORS, FUSION (Phase transformation), THERMODYNAMIC equilibrium, PARTICLES (Nuclear physics), COLLISIONS (Nuclear physics), CHAOS theory, TURBULENCE
Abstract

RFX-mod self-organized single helical axis (SHAx) states provide a unique opportunity to advance 3D fusion physics and establish a common knowledge basis in a parameter region not covered by stellarators and tokamaks. The VMEC code has been adapted to the reversed-field pinch (RFP) to model SHAx equilibria in fixed boundary mode with experimental measurements as constraint. The averaged particle diffusivity over the helical volume, estimated with the Monte Carlo code ORBIT, has a neoclassical-like dependence on collisionality and does not show the 1/ν trend of un-optimized stellarators. In particular, the helical region boundary, corresponding to an electron transport barrier with zero magnetic shear and improved confinement, has been investigated using numerical codes common to the stellarator community. In fact, the DKES/PENTA codes have been applied to RFP for local neoclassical transport computations, including radial electric field, to estimate thermal diffusion coefficients in the barrier region for typical RFX-mod temperature and density profiles. A comparison with power balance estimates shows that residual chaos due to secondary tearing modes and small-scale turbulence still contribute to drive anomalous transport in the barrier region. [ABSTRACT FROM AUTHOR]

Published
2011
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14. The prospects for magnetohydrodynamic stability in advanced tokamak regimes*.

Author

Manickman, J., Chance, M.S., Jardin, S.C., Kessel, C., Monticello, D., Pomphrey, N., Reiman, A., Wang, C., and Zakharov, L.E.

Subjects
TOKAMAKS, BOUNDARY value problems
Abstract

Presents a stability analysis of advanced regime tokamaks. Inclusion of configurations where the ratio of the bootstrap current to the total plasma current approached unity; Discussion of scenarios in the context of Toroidal Physics Experiment; Stability of the configuration is the external boundary conditions are relaxed.

Published
1994

15. Robustness and flexibility in compact quasiaxial stellarators: Global ideal magnetohydrodynamic stability and energetic particle transport.

Author

Redi, M. H., Diallo, A., Cooper, W. A., Fu, G. Y., Nu¨hrenberg, C., Pomphrey, N., Reiman, A. H., and Zarnstorff, M. C.

Subjects
STELLARATORS, TOKAMAKS
Abstract

Concerns about the flexibility and robustness of a compact quasiaxial stellarator design are addressed by studying the effects of varied pressure and rotational transform profiles on expected performance. For thirty, related, fully three-dimensional configurations the global, ideal magnetohydrodynamic (MHD) stability and energetic particle transport are evaluated. It is found that tokamak intuition is relevant to understanding the magnetohydrodynamic stability, with pressure gradient driving terms and shear stabilization controlling both the periodicity preserving, N=0, and the nonperiodicity preserving, N=1, unstable kink modes. Global kink modes are generated by steeply peaked pressure profiles near the half radius and edge localized kink modes are found for plasmas with steep pressure profiles at the edge as well as with edge rotational transform above 0.5. Energetic particle transport is not strongly dependent on these changes of pressure and current (or rotational transform) profiles, although a weak inverse dependence on pressure peaking through the corresponding Shafranov shift is found. While good transport and MHD stability are not anticorrelated in these equilibria, stability only results from a delicate balance of the pressure and shear stabilization forces. A range of interesting MHD behaviors is found for this large set of equilibria, exhibiting similar particle transport properties. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

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