Access to a New Plasma Edge State with High Density and Pressures using the Quiescent $H$ Mode

W. M. Solomon, P. B. Snyder, K. H. Burrell, M. E. Fenstermacher, A. M. Garofalo, B. A. Grierson, A. Loarte, G. R. McKee, R. Nazikian, and T. H. Osborne

Phys. Rev. Lett. 113, 135001 – Published 24 September 2014

Abstract

A path to a new high performance regime has been discovered in tokamaks that could improve the attractiveness of a fusion reactor. Experiments on DIII-D using a quiescent $H$ -mode edge have navigated a valley of improved edge peeling-ballooning stability that opens up with strong plasma shaping at high density, leading to a doubling of the edge pressure over the standard $H$ mode with edge localized modes at these parameters. The thermal energy confinement time increases as a result of both the increased pedestal height and improvements in the core transport and reduced low- $k$ turbulence. Calculations of the pedestal height and width as a function of density using constraints imposed by peeling-ballooning and kinetic-ballooning theory are in quantitative agreement with the measurements.

Received 23 June 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.135001

Authors & Affiliations

W. M. Solomon^1,*, P. B. Snyder², K. H. Burrell², M. E. Fenstermacher³, A. M. Garofalo², B. A. Grierson¹, A. Loarte⁴, G. R. McKee⁵, R. Nazikian¹, and T. H. Osborne²

¹Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
²General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
³Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
⁴ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 Saint Paul Lez Durance Cedex, France
⁵University of Wisconsin-Madison, Madison, Wisconsin 53706, USA