Optical radiation from the sputtered species under gas excitation by the products of the 6Li(n,α)3H nuclear reaction

Abstract

The emission spectra during alkali metal sputtering into noble gases excited by the products of 6Li(n,α)3H nuclear reaction were studied. Lithium in the form of a capillary-porous structure (CPS) was heated up to a temperature of 730 K. At a temperature in the 520–620 K range, depending on a type of gas medium, intense radiation was observed for lines of lithium and lines of sodium and potassium found as impurities in lithium. The process activation energy (155–161 kJ/mol) obtained from the dependence of the optical radiation intensity on the lithium layer temperature is in good agreement with the lithium evaporation energy values. The vapour density that is significantly higher than that saturated lithium vapour under normal thermal heating was created by the α-particles and tritium nuclei released from the lithium layer and when the opposite wall was bombarded. Excitation of the sputtered lithium atoms occurs as the result of the plasma-chemical reactions in the gas. The Penning process for the lithium atoms is suggested to be the main channel for the excitation transmission from the noble gases to the lithium atoms.