Studies of the relaxation and confinement of hot anisotropic ions are considered to be the key elements of the gas dynamic trap (GDT) experimental research programme. The method of confinement study described consists essentially in thecomparison of measured ion parameters with those predicted by computer simulations. To realize this approach a set of diagnostics for the measurements of local and global parameters of the fast ions has been developed. In particular, this setincludes diagnostics to measure the local energy and the angular distribution functions. For numerical studies of the fast ion dynamics a Monte Carlo code based on the theory of two body Coulomb collisions has been elaborated. Comparison of the experimental data with the results of the simulation clearly demonstrates that the fast ion characteristic relaxation times in the warmtarget plasma are close to those determined by binary Coulomb collisions. Significant anomalous energy losses or scattering of fast ions have not been observed as yet. The measurements provide a maximum density of the fast ions with mean energy ofabout 8 keV up to 1013 cm-3, in good agreement with computer simulations. The increase of the neutral beam power and improved vacuum conditions of GDT made possible the access to plasma β of as high as 30%.
Modelling the Alfvén eigenmode induced fast-ion flow measured by an imaging neutral particle analyzer
A large-orbit model of fast ion slowing down during ICRH: Comparison with JET data