Abstract:
Results of an experimental study of the kinetics of luminescence observed when a metallic cadmium foil is bombarded in a helium medium by a 3-ns pulsed beam of 150-keV fast electrons are reported. The foil was irradiated at gas pressures from 76 to 2280 Torr. At a foil temperature of $T$ = 240$^\circ$C, the de-excitation time of the Beitler levels of the Cd II ion was measured as a function of the buffer gas pressure and the constant of collision quenching of the $5s^2$$^2D_{5/2}$ level of Cd II by He atoms was determined as $k\approx$ 3 $\cdot$ 10$^{-29}$ cm$^6$/s. The experimental data were compared with calculations performed for the gas–vapor mixture in order to find the fraction of excited Cd II ions in the $5s^2$$^2D_{5/2}$ state produced directly as a result of sputtering of metallic cadmium by high-energy electrons and by components of the helium plasma. At a helium buffer gas pressure of $P\le$ 2.5 atm and a temperature of the cadmium target of $T$ = 240$^\circ$C, the value of this quantity was found to be $\alpha$ = 0.28 + 0.23$P$ (where $P$ is the helium pressure in atmospheres).
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