Modeling the excitation of global Alfven modes by an external antenna in the Joint European Torus (JET)
- JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom)
- Association Euratom-FOM, FOM Institute for Plasma Physics, ``Rijnhuizen,`` P.O. Box 1207, 3430 BE, Nieuwegein (Netherlands)
The active excitation of global Alfven modes using the saddle coils in the Joint European Torus (JET) [{ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Nuclear} {ital Fusion} {ital Research} 1984, Proceedings of the 10th International Conference, London (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 11] as the external antenna, will provide information on the damping of global modes without the need to drive the modes unstable. For the modeling of the Alfven mode excitation, the toroidal resistive magnetohydrodynamics (MHD) code CASTOR (Complex Alfven Spectrum in TORoidal geometry) [18{ital th} {ital EPS} {ital Conference} {ital On} {ital Controlled} {ital Fusion} {ital and} {ital Plasma} {ital Physics}, Berlin, 1991, edited by P. Bachmann and D. C. Robinson (The European Physical Society, Petit-Lancy, 1991), Vol. 15, Part IV, p. 89] has been extended to calculate the response to an external antenna. The excitation of a high-performance, high beta JET discharge is studied numerically. In particular, the influence of a finite pressure is investigated. Weakly damped low-{ital n} global modes do exist in the gaps in the continuous spectrum at high beta. A pressure-driven global mode is found due to the interaction of Alfven and slow modes. Its frequency scales solely with the plasma temperature, not like a pure Alfven mode with a density and magnetic field.
- OSTI ID:
- 165181
- Journal Information:
- Physics of Plasmas, Vol. 2, Issue 5; Other Information: PBD: May 1995
- Country of Publication:
- United States
- Language:
- English
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