Projects per year
Abstract
A numerical integration method for guidingcenter orbits of charged particles in toroidal fusion devices with threedimensional field geometry is described. Here, high order interpolation of electromagnetic fields in space is replaced by a special linear interpolation, leading to locally linear Hamiltonian equations of motion with piecewise constant coefficients. This approach reduces computational effort and noise sensitivity, while the conservation of total energy, magnetic moment and phase space volume is retained. The underlying formulation treats motion in piecewise linear fields exactly and, thus, preserves the noncanonical symplectic form. The algorithm itself is only quasigeometric due to a series expansion in the orbit parameter. For practical purposes, an expansion to the fourth order retains geometric properties down to computer accuracy in typical examples. When applied to collisionless guidingcenter orbits in an axisymmetric tokamak and a realistic threedimensional stellarator configuration, the method demonstrates stable longterm orbit dynamics conserving invariants. In Monte Carlo evaluation of transport coefficients, the computational efficiency of quasigeometric integration is an order of magnitude higher than with a standard fourth order Runge–Kutta integrator.
Original language  English 

Article number  122508 
Journal  Physics of Plasmas 
Volume  27 
Issue number  12 
DOIs  
Publication status  Published  Dec 2020 
ASJC Scopus subject areas
 Condensed Matter Physics
Projects
 1 Active

EUROFusion  Transport and Heating in Fusion Plasmas
Kernbichler, W., Albert, C., Eder, M., Kasilov, S., Markl, M., Buchholz, R., Graßler, G. S., Kamendje, R. L., Babin, R. & Lainer, P.
1/01/21 → 31/12/23
Project: Research project