Dissemin is shutting down on January 1st, 2025

Published in

IOP Publishing, Nuclear Fusion, 6(50), p. 064010, 2010

DOI: 10.1088/0029-5515/50/6/064010

Links

Tools

Export citation

Search in Google Scholar

Overview of L–H power threshold studies in NSTX

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Orange circle
Postprint: archiving restricted
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

A summary of results from recent L–H power threshold (P LH) experiments in the National Spherical Torus Experiment is presented. First P LH (normalized linearly by plasma density) was found to be a minimum in double-null configuration, tending to increase as the plasma was shifted more strongly towards lower- or upper-single null configuration with either neutral beam or rf heating. The measured P LH/n e was comparable with neutral beam or rf heating, suggesting that rotation was not playing a dominant role in setting the value of P LH. The role of triangularity (δbot) in setting P LH/n e is less clear: while 50% less auxiliary heating power was required to access H-mode at low δbot than at high δbot, the high δbot discharges had lower ohmic heating and higher dW/dt, leading to comparable loss of power over a range of δbot. In addition, the dependences of P LH on the density, species (helium versus deuterium), plasma current, applied non-axisymmetric error fields and lithium wall conditioning are summarized.