Kinetic Alfvén waves in a deuterium-tritium fusion plasma with slowing-down distributed α-particles

The dispersion relation and damping rate of kinetic Alfvén waves (KAWs) in a deuterium-tritium fusion plasma with slowing-down distributed \alpha-particles are investigated using the kinetic theory. The variations of wave frequency and damping rate with respect to the \alpha concentration (n_\alpha/n_\rm e) and perpendicular wave number (k_ \bot ) are studied from a numerical way. The results show that the fluctuation of \alpha concentration slightly affects the frequency and damping rate of KAWs at low n_\alpha/n_\rm e. In addition, the frequency and the damping rate increase as the k_ \bot and the background temperature T_\rm e increase. For comparison, the calculations are performed also in the case of \alpha-particles following an equivalent Maxwellian distribution. For a given k_ \bot , the value of the frequency obtained in the slowing-down distribution case is smaller than that obtained in the Maxwellian distribution case. Conversely, the value of the damping rate obtained in the slowing-down distribution case is slightly larger than that obtained in the Maxwellian distribution case.