Neutron flux distribution on the wall of toroidal controlled thermonuclear reactor devices with elongated cross section

Abstract

The neutron flux distribution on the wall of a toroidal CTR device with strongly elongated cross section is calculated. On the inner and outer cylindrical walls (belt-pinch device) the flux distribution has a plateau region with a half-width equal to about the height of the plasma. The maximum flux is found on the outer cylinder and in the symmetry plane (z ₀=0). The neutron flux asymmetry and reductionη of the mean wall loading are determined. For standard data anη of 57% is computed. This is mainly due to the flux profiles on the cylindrical walls and does not depend sensitively on the toroidal curvature. For standard parameters the inner cylinder absorbs 22.6%, the outer cylinder 68.6% and the end plates together 8.8% of the total neutron emission. The corresponding values for a straight device with the same coil and plasma cross section are 44%, 44% and 12%. A reduction of toroidal curvature diminishes flux asymmetry between the inner and outer cylinders. The maximum flux and minimumη-value are obtained at a large torus radius equal to two times the coil width. For small aspect ratios (R _t W0.5) the neutron flux through the inner cylinder becomes so small that its interior may be filled with a material other than a blanket material, e.g. with an iron core.