Localized heat deposition on tokamak first wall due to ripple-trapped loss of suprathermal ions produced by NBI

Heat deposition on the first wall due to ripple-trapped loss particles produced in the slowing-down process of injected beam ions is investigated in a reactor-grade tokamak. Ripple-trapped particles enter specific narrow areas of the first wall in the course of their toroidal drift and cause a significantly large heat loading, which will become one of the important problems in the design of the tokamak first wall. Localized heat loads due to ripple-trapped loss ions may reach a magnitude of 1 MW·m −2 for the next-generation tokamak.