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Abstract

Lower Hybrid waves produce suprathermal electrons at densities below the onset of ion interaction. By appropriate choice of plasma and wave parameters the electron distribution function can be specifically influenced by producing a suprathermal tail or a runaway population. With improved local deposition of LHpower this provides a means of local modification of the electrical conductivity. Lower Hybrid Current Drive has high efficiencies in a combined operation with inductive current drive at high electric field. The results of scaling studies on the LH current drive efficiency are well explained by existing theories. The decoupling of temperature and current profiles with LHcurrent drive can be used for external control of j(r) independent of the heat deposition by additional heating. This allows the stabilising of sawteeth by increasing q(o) above 1. A Lower Hybrid System for profile control on JET should aim at power deposition at the plasma periphery. Problems with wave propagation due to toroidal effects and absorption of waves on thermal electrons and fast ions prevent penetration of LH waves into the central plasma region. Also the high power requirements for LHcurrent drive in the high density region would discard such a scheme. With LH current drive in the low density edge region control of the plasma current profile on JET might be attained at moderate LHpower.

Additional information

Authors: SOELDNER F X, MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING (GERMANY);BRAMBILLA M, MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING (GERMANY);LEUTERER F, MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING (GERMANY);MUENICH M MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING (GERMANY), MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING (GERMANY)
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP III/111, 1986
Record Number: 1989126009100 / Last updated on: 1988-02-01
Category: PUBLICATION
Available languages: en