On ray stochasticity during lower hybrid current drive in tokamaks
A comprehensive and detailed analysis is presented of the importance of toroidally induced ray stochasticity for the modelling of lower hybrid current drive and for the dynamics of the launched power spectrum. A combined ray tracing and Fokker-Planck code is used and the injected lower hybrid power distribution in poloidal angle and in parallel wave index is accurately represented by taking into account the poloidal extent of the antenna, and by efficiently covering the full range of its radiated spectrum. The importance of the balance between the wave damping and the exponential divergence of nearby ray trajectories in determining the shape of the predicted lower hybrid power deposition profiles is emphasised. When the number of rays used is sufficient to cover the affected region of the launched power spectrum densely, code predictions are stable with respect to small changes in initial conditions and plasma parameters and consistent with experimental data.
Bibliographic Reference: Report: EUR-CEA-FC-1467 EN (1992)
Availability: Available from CEA, Département de Recherches sur la Fusion Contrôlée, Centre d'Etudes de Cadarache, 13108 Saint-Paul-lez-Durance (FR), as EUR-CEA-FC-1467, 1992
Record Number: 199211316 / Last updated on: 1994-11-29
Original language: en
Available languages: en