Evolution of α-particle distribution in burning tokamaks including energy dependent α transport effects

Standard Fokker-Planck codes calculating the α particle distribution function evolution describe the simple balance between the fusion source term and the collision operator neglecting radial diffusion. In the present paper the effects of radial α-diffusion have been studied by means of a modified kinetic equation containing loss terms due to α-particle and heat transport. Energy dependent transport coefficients are admitted. As a second method, the effect of energy dependence of the spatial α diffusion coefficient is included using a multi group set of α-particle continuity equations. We have determined the sensitivity of the α-evolution to the energy dependence of a diffuson coefficient Dα(E) for 2 cases: (i) a generic model for an anomalous Dα(E). (ii) Dα(E) corresponding to stochastic ripple losses.