Role of antenna screen angle during ICRF heating in JETFunded under: FP1-FUSION 9C
To test the role of the antenna screen angle during high power ICRF heating in JET two identical heating experiments were carried out. In the first experiment the magnetic field was practically aligned with the screen elements whereas in the second experiment the toroidal field was reversed to produce an angle of 25 degrees between the elements and the field. Clear differences in the impurity influxes, the heating efficiency and the coupling resistance were observed between discharges with the field normal and reversed. A numerical code based on a three-dimensional full wave calculation of antenna coupling can qualitatively reproduce the observed difference in coupling resistance. The results suggest that the excitation of the evanescent slow wave is responsible for the observed difference in heating and impurity levels. The results indicate the importance of the Faraday screen design for the levels of RF enhanced metal influxes originating at the screen. This should be of a particular relevance for the ICRF antennae in a reactor where most of the interaction between the RF fields and the plasma edge is expected to take place around the antennae structures.
Bibliographic Reference: Report: JET-P(88)76 EN (1988)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 198910839 / Last updated on: 1994-12-01
Original language: en
Available languages: en