Comparison of the performance of ICRF antennas with and without Faraday shield on TEXTOR
After the first demonstration of successful operation with ion cyclotron resonance heating (ICRH) on TEXTOR using an antenna without Faraday shield (FS), a further comparison of an antenna with FS and an antenna without FS has been made over a wide range of plasma conditions (including the improved confinement regime on TEXTOR), in zero phase and pi phase operation, using various heating scenarios. No restriction in the operational conditions was found to exist for the screenless antenna. A theoretical analysis shows that antenna side limiters are sufficient to protect the antenna conductor from the plasma and that the plasma in front of the antenna can take over the role of the FS without introducing additional losses. The impact of the operation with both antennae on plasma temperature, density, energy and impurities is discussed in detail. It is found that an antenna pair without shield, but with the antenna feeder area covered, has the same heating efficiency and overall performance as an antenna with FS when pi phasing is used. In zero phase operation, the antenna with FS performs slightly better. First experiments in which an antenna without shield and without coverage of the antenna feeder area is used are discussed briefly.
Bibliographic Reference: Article: Nuclear Fusion, Vol. 32 (1992) No. 11, pp. 1913-1925
Record Number: 199310122 / Last updated on: 1994-11-29
Original language: en
Available languages: en