Abstract
A fast and efficient numerical algorithm using energy conservation is developed to study the interaction of high energy particles with a toroidicity induced Alfven eigenmode (TAE). A Hamiltonian guiding centre code is used to simulate the alpha particle motion and a non-linear delta f scheme is employed to calculate the wave-particle energy exchange. For a single TAE mode, the particle radial excursion is much less than the spacing between the resonances produced by the poloidal harmonics for International Thermonuclear Experimental Reactor parameters. Modification of the particle distribution leading to mode saturation is observed. A TAE is found in some cases to cause loss through induced ripple trapping