Dynamical conservation of invariants by toroidal trajectories of guiding centers
The classical problem of calculating toroidal trajectories is treated by comparing the results of two different methods in a given magnetic configuration, a standard divergence-free magnetic field model. The aim of the present work is to adapt the analytical criteria of Mercier et al. for classical toroidal trajectories, and to examine numerically the dynamical conservation of the toroidal invariant, before studying, in future works, more involved chaotic situations with magnetic islands. Additional precisions to those used in previous studies have been introduced. For example, a modified standard model is used for the magnetic field, ensuring a manifestly divergence-free field. Moreover, the contribution of the poloidal field to the total strength of the magnetic field is considered. These corrections are found to contribute to the analytical expression of the conserved toroidal momentum. The present analysis brings a clear description of some other, less well-known types of trajectories, namely the stagnation orbits, the smallest D-shape banana, and moreover some small circulating deflated bananas, some huge classical bananas (potatoes), and the largest puffed bananas which exhibit only local mirroring, along with several kinds of escaping or open trajectories which are of importance for fast ion losses and target damages in the machines.
Bibliographic Reference: Report: EUR-CEA-FC-1438 EN (1992) 95 pp.
Availability: Available from CEA, Département de Rercherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Record Number: 199210859 / Last updated on: 1994-12-02
Original language: en
Available languages: en