دانلود رایگان مقاله انتگرال هندسی برای مدار ذره باردار در دستگاه فیوژن متقارن

Abstract

A semi-analytical geometric integrator of guiding centre orbits in an axisymmetric tokamak is described. The integrator preserves all three invariants of motion up to computer accuracy at the expense of reduced orbit accuracy and it is roughly an order of magnitude more efficient than a direct solution of the equations of guiding centre motion with a standard high order adaptive ODE integrator.

4. Summary

The semi-analytical geometric integrator described here has roughly an order of magnitude higher efficiency than a conventional method for guiding centre orbit integration. Essentially this is due to the fact that all analytical results employed by this integrator are expressed in terms of elementary functions, which are intrinsic functions of FORTRAN compilers with a pertinent CPU cost of the order of a single algebraic operation. In transport modelling, the efficiency of this geometric integrator is even higher because the track length estimator frequently used for the evaluation of macroscopic parameters from Monte Carlo test particle distributions does not require any additional search of orbit intersections with the given mesh. These data are obtained by the geometric integrator as a by-product of orbit tracing. The integrator has been already employed in 2D kinetic transport modelling in a tokamak [4] and can also be applied for the modelling of kinetic effects in combination with 2D fluid and neutral transport codes.