Neutron yield as a measure of achievement nuclear fusion using a mixture of deuterium and tritium isotopes

Abstract

A mixture of deuterium (D) and tritium (T) is the most likely fuel for fusion reactors and hence the D(d, n)3He and T(d, n)4He fusion reactions are the ones that will fire fusion reactors in the future. Both of the fusion reactions produce neutrons which escape form the reactor core and can be measured directly outside the core. As the neutrons have large mean free path and neutral charge, they readily carry information about the burning fusion plasma from inside to outside the reactor core without being affected by electric ormagnetic fields. From the produced neutrons of the D(d, n)3He and T(d, n)4He fusion reactions, the neutron yield of each reaction and the neutron yield ratio of the two reactions are calculated. This ratio is of critical importance for controlling the fusion fuel burning which is a high priority issue for fusion reactor performance. Because it is very difficult to measure this ratio experimentally, accurate theoretical calculations of the neutron yield ratio besides the related deuterium and tritium energy spectra in the fusion plasma are needed. In the present work, neutron yields of the D(d, n)3He and T(d, n)4He fusion reactions have been calculated using the MCUNED, the ENEA-JSI, the DDT codes and the Geant4 toolkit. The related deuterium and tritium energy spectra have been calculated by the MCUNED code. The relation between the ion temperature and the neutron yield in the imploded fusion plasma is discussed. Calculations are compared to the available experimental data. Comparing to the other codes, the spectrum of the fusion neutrons simulated by the MCUNED is the only one that fit the experimental data.