Model for the Transition to the Radiatively Improved Mode in a Tokamak

Partners in the Trilateral Euregio Cluster; M. Z. Tokar; J. Ongena; B. Unterberg; R. R. Weynants

doi:10.1103/PhysRevLett.84.895

Model for the Transition to the Radiatively Improved Mode in a Tokamak

M. Z. Tokar, J. Ongena, B. Unterberg, and R. R. Weynants (Partners in the Trilateral Euregio Cluster)

Phys. Rev. Lett. 84, 895 – Published 31 January 2000

Abstract

A model for the transition to the radiatively improved (RI) mode triggered in tokamaks by seeding of impurities is proposed. This model takes into account that with increasing plasma effective charge the growth rate of the toroidal ion temperature gradient (ITG) instability, considered nowadays as the dominant source of anomalous energy losses in low-confinement (L) mode, decreases. As a result the plasma density profile peaks due to an inward convection generated by trapped electron turbulence. This completely quenches ITG induced transport and a bifurcation to the RI mode occurs. Conditions necessary for the L-RI transition are investigated.

Received 20 May 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.895

Authors & Affiliations

M. Z. Tokar¹, J. Ongena², B. Unterberg¹, and R. R. Weynants² (Partners in the Trilateral Euregio Cluster)

¹Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Association, D-52425 Jülich, Germany
²Laboratoire de Physique des Plasmas–Laboratorium voor Plasmafysica, “Association EURATOM–Belgian State,” Ecole Royale Militaire–Koninklijke Militaire School, B-1000, Brussels, Belgium