京大総合研究１０号館３０３号室

小川駿氏（Universite de Aix-Marseille）

『Effect of unstable fixed points in magnetized plasmas.』

The topic of this talk is a test ion motion in a cylindrical magnetic field. The back ground field consists of non-zero strong static magnetic field with periodic boundary condition and null electric field. The main topic of this talk is on the effect of unstable fixed points for individual particles, which bring about the chaos [1,2]. This chaos indicates that there is no invariant associated with the magnetic moment which is assumed in a gyrokinetic theory [3,4] widely used for numerical simulation of magnetized plasmas [5,6]. Further we investigate ``which kinds of magnetic fields exhibit unstable fixed points at low energy?'' and ``when and where they appear?'' and would like to discuss ``how do they affect the mesoscopic properties of plasmas?'' [7], for instance, local pressure or density gradients in the local equilibrium. [1] A. I. Neishtadt, Change of an adiabatic invariant at a separa- trix, Sov. J. Plasma Phys. 12, 568 (1986). [2] J. L. Tennyson, J. R. Cary, and D. F. Escande, Change of the adiabatic invariant due to separatrix crossing, Phys. Rev. Lett. 56, 2117 (1986). [3] A. H. Boozer, Physics of magnetically confined plasmas, Rev. Mod. Phys. 76, 1071 (2004). [4] E. Sugama, Gyrokinetic theory, J. Plasma Fusion Res. 79, 107, (2003) (in Japanese). [5] B. Cambon, X. Leoncini, M. Vittot, R. Dumont, and X. Garbet, Chaotic motion of charged particles in toroidal magnetic configurations, Chaos 24, 033101 (2014). [6] S. Ogawa, B. Cambon, X. Leoncini, M. Vittot, D. del-Castillo-Negrete, G. Dif-Pradalier, and X. Garbet, Full particle orbit effects in regular and stochastic magnetic fields,Phys. Plasmas 23, 072506 (2016). [7] S. Ogawa, X. Leoncini, A. Vasiliev, and X. Garbet, Creating steep density profile with a separatrix, arXiv:1611.00063v1. (New version will appear soon, and title will be changed.)

Last modified: Thu Dec 8 14:58:12 JST 2016