Lower hybrid experiments on ASDEX in 1989
Lower hybrid experiments were resumed on ASDEX with a system at 2.45 GHz. Coupling of the grill antenna was considerably improved after reshaping the surrounding protection limiters. Detailed studies of current drive were conducted in ohmic target plasmas and also in combination with NBI. Variations of the current drive efficiency can be closely correlated with variations of the broadening of the lower hybrid pump wave. Improved global energy confinement is obtained with LH at low density. This improvement can be attributed to the superior confinement of the suprathermal electrons. Particle confinement is also improved with LH current drive. The MHD activity is strongly influenced by LH current drive. Sawteeth can be suppressed in OH- and NBI-heated discharges with LH current drive. Stabilisation of the m=1 mode is achieved with LH current drive at low N(parallel), in OH target plasmas and also in combination with NBI. After suppression of the m=1 mode, strong central electron heating and peaking of the radial electron temperature profile are obtained. The current profile can be controlled by varying the LH spectrum. Current and temperature profiles can thus be decoupled and all MHD modes be simultaneously suppressed by LH current drive.
Bibliographic Reference: Report: IPP III/162 EN (1990) 58 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199110050 / Last updated on: 1994-12-02
Original language: en
Available languages: en