Hamiltonian nontwist map for magnetic field lines with locally reversed shear in toroidal geometry

被引:73
作者
Balescu, R [1 ]
机构
[1] Free Univ Brussels, Assoc Euratom Etat Belge Fus, B-1050 Brussels, Belgium
来源
PHYSICAL REVIEW E | 1998年 / 58卷 / 03期
关键词
D O I
10.1103/PhysRevE.58.3781
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
A simple Hamiltonian map is constructed, fulfilling the minimum requirements for the representation of a tokamak magnetic field in reversed shear configuration. This "revtokamap" is atypical nontwist map, for which many theorems of "traditional" dynamical systems theory do not apply. It is shown that in the revtokamap, for finite stochasticity parameter, a critical surface appears, separating an external, globally stochastic region from a robust nonstochastic core region. This phenomenon of ''semiglobal chaos'' is analogous to the well-known appearance of an internal transport barrier in reversed shear tokamak experiments. An analysis of the fixed points reveals a variety of bifurcation and reconnection phenomena, which appear to be generic for nontwist maps with an impenetrable polar axis.
引用
收藏
页码:3781 / 3792
页数:12
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