Focus neutron spectra. 2nd part: calculation of a distribution function of accelerated deuterons from the experimental spectra

Bernstein simplifying hypotheses are used to describe the FOCUS plasma producing nuclear reactions, by means of two populations: the accelerated deuterons described by the space-time mean value of their single velocity distribution f1(E(d), theta(d)); and a beam of target deuterons with a kinetic energy E(T). The neutron spectrum S(M)(P0,E,theta(n)) being obtained by a time-of-flight measurement, a possible determination of the function f1 (E(d), theta(d)) giving the same spectrum is developed. When theta(n) is not zero, the Gauss-Legendre two-step method used for the programming allows a precise computation for the infinite branches. There is no difficulty in the case where theta(n)=0,π. A discrete solution is developed from two or three different values of theta(n) and a ten energy values with 100keV steps. The minimization leads to solving a linear system by the Gauss-Seidel method