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Title: Large transport-induced operation limits of tokamak plasmas

Abstract

The two-dimensional phase space of tokamak edge plasmas identified in the numerical simulations by B. Rogers et al. [Phys. Rev. Lett. 81, 4396 (1998)] provides a unique prescription for the various regimes of operation of tokamak plasmas. Recent observations on Alcator C-Mod of these regimes, identified in terms of the above-mentioned phase-space parameters, is found to be in very good agreement with simulation results of Rogers et al. In this phase space, they identified a boundary at high collisionality that defines a region that is operationally inaccessible owing to very large transport in the edge region of the tokamaks. A second boundary at moderate to low collisionality is also indicated and associated with the transition between the low-confinement mode and the high-confinement mode. The high collisionality boundary is of particular interest since it appears to be fundamentally related to the empirical 'density limit' that is observed in tokamaks. In this Letter, we provide a theory that determines the conditions necessary for very high transport and hence the origin of the inaccessible 'density limit' in the two-dimensional phase space.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)
  2. (India)
  3. (United States)
Publication Date:
OSTI Identifier:
20974814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 2; Other Information: DOI: 10.1063/1.2436736; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALCATOR DEVICE; BOUNDARY LAYERS; NUMERICAL ANALYSIS; PHASE SPACE; PLASMA; PLASMA CONFINEMENT; PLASMA DENSITY; PLASMA SIMULATION; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Guzdar, P. N., Kleva, R. G., Kaw, P. K., Singh, R., LaBombard, B., Greenwald, M., Institute for Plasma Research, Gandhinagar, Gujarat 78712, and Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, Massachusetts 02139. Large transport-induced operation limits of tokamak plasmas. United States: N. p., 2007. Web. doi:10.1063/1.2436736.
Guzdar, P. N., Kleva, R. G., Kaw, P. K., Singh, R., LaBombard, B., Greenwald, M., Institute for Plasma Research, Gandhinagar, Gujarat 78712, & Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, Massachusetts 02139. Large transport-induced operation limits of tokamak plasmas. United States. doi:10.1063/1.2436736.
Guzdar, P. N., Kleva, R. G., Kaw, P. K., Singh, R., LaBombard, B., Greenwald, M., Institute for Plasma Research, Gandhinagar, Gujarat 78712, and Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, Massachusetts 02139. Thu . "Large transport-induced operation limits of tokamak plasmas". United States. doi:10.1063/1.2436736.
@article{osti_20974814,
title = {Large transport-induced operation limits of tokamak plasmas},
author = {Guzdar, P. N. and Kleva, R. G. and Kaw, P. K. and Singh, R. and LaBombard, B. and Greenwald, M. and Institute for Plasma Research, Gandhinagar, Gujarat 78712 and Plasma Science and Fusion Center, Massachusetts Institute of Technology, 175 Albany Street, Cambridge, Massachusetts 02139},
abstractNote = {The two-dimensional phase space of tokamak edge plasmas identified in the numerical simulations by B. Rogers et al. [Phys. Rev. Lett. 81, 4396 (1998)] provides a unique prescription for the various regimes of operation of tokamak plasmas. Recent observations on Alcator C-Mod of these regimes, identified in terms of the above-mentioned phase-space parameters, is found to be in very good agreement with simulation results of Rogers et al. In this phase space, they identified a boundary at high collisionality that defines a region that is operationally inaccessible owing to very large transport in the edge region of the tokamaks. A second boundary at moderate to low collisionality is also indicated and associated with the transition between the low-confinement mode and the high-confinement mode. The high collisionality boundary is of particular interest since it appears to be fundamentally related to the empirical 'density limit' that is observed in tokamaks. In this Letter, we provide a theory that determines the conditions necessary for very high transport and hence the origin of the inaccessible 'density limit' in the two-dimensional phase space.},
doi = {10.1063/1.2436736},
journal = {Physics of Plasmas},
number = 2,
volume = 14,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}