Use of the Li+T6 nuclear reaction for diagnostics of energetic particles in burning plasmas

Application of reaction-produced γγ-rays to diagnostics of energetic particles in burning plasmas is analyzed. Particularly, we focus on 0.981 MeV γγ-rays emitted in the Li6(t,p1γ)Li8 nuclear reaction solely governed in the plasmas by energetic tritons. It is shown that these γγ quanta can serve as a promising tool to diagnose αα knock-on tritons and αα-particles confined in burning DT plasmas. Key parameters of the αα knock-on triton population and the αα-particle confinement property can be obtained by comparing the experimental γγ-ray yield and spectrum with theoretical slowing-down calculations. Even if the γγ-ray spectral shape cannot be acquired, one can monitor densities of these tritons and αα-particles at energies of 0.6–1.8 MeV and 2.0–3.5 MeV, respectively, in a nearly steady-state plasma. The 0.981-MeV photons also would help to display time evolution of the αα-particle population in experiments of deuterium plasmas with pulsed tritium beam shots.