Calculations of high energy particle losses for stellarators in real space coordinates

摘要

In numerical studies of collisionless charged particle losses (in particular, a-particle losses) in stellarators the most consistent approach is-realized in, codes which perform a direct computation of particle losses using the guiding center drift equations to. follow trapped particle orbits until such particles are lost. Such an approach has been realized, in particular, in [1] in which, a huge sample of particles is followed with random starting points as well as random values of pitch angles on an initial magnetic surface. It should be noted that computations in [1] are performed in magnetic coordinates. A final conclusion about properties of the pertinent configuration can be only made when taking into account the influence of. islands and stochastic regions which may exist in a real magnetic field and. which can be analyzed only in real space coordinates. Therefore, for this study a code analogous-talhat of [!] is worked out for the case of a stellarator magnetic field'given in real, space coordinates. In this case calculations can be made in, a magnetic field with three-dimensional inhomogeneity in presence of stochastic regions and island magnetic surfaces. This field can be calculated in-real space from coil currents using the Biot-Savart law as well as from three-dimensional magneto-hydrodynamic (MHD) finite j8 equilibrium codes such as PIES or HINT. Calculations with this code are. performed for the life time of a-particles in magnetic configurations of U-2M (Uragan-2ivl) and W7-X, adapted to reactor plasma parameters.