Measurements of Mo I S/XB values

Abstract

The number of ionization events per photon, i.e. S/XB value, of Mo I lines has been determined by taking a ratio of the sputtered Mo flux, ΓSptMo, to the line-of-sight integrated Mo I emission intensity in weakly ionized (ionization degree of ∼1–10%) He plasmas in the linear divertor plasma simulator PISCES-B under the following plasma parameters: electron density ne ∼ (0.6–1.3) × 1019 m−3, electron temperature Te ∼ 10–30 eV, ion flux Γi ∼ (0.9–1.2) × 1023 m−2 s−1 and incident ion energy to the Mo target Ei ∼ 60 eV. For these conditions, most of the sputtered Mo atoms are ionized in the plasma column. While measured S/XB values for z 5P° → a 5S (550.6, 553.3 and 557.0 nm) are systematically higher than theoretically calculated values provided in the Atomic Data and Analysis Structure database by a factor of ∼2–5, agreement for the other transitions, y 7P° → a 7S (313.3, 317.0 and 319.4 nm) and z 7P° → a 7S (379.8, 386.4 and 390.3 nm), is more satisfactory (within a factor of 2).