\textit{S/XB} measurements for Mo I and W I lines

In the spectroscopic method to determine sputtered impurity influxes, the ionization events per photon (\textit{S/XB}) value is essential to convert the line emission intensity into a particle flux [1]. However, experimental data of \textit{S/XB} values for Mo I are scarce and for W I sometimes inconsistent. In the linear divertor simulator PISCES-B, we have determined \textit{S/XB} values of Mo I and W I lines by measuring the line emission of sputtered atoms by He or Ar plasma bombardment. While our measured values for the Mo I transition of $z$ $^{7}$P$^{o} \rightarrow \quad a \quad ^{7}$S (379.8, 386.4, 390.3 nm) are systematically $\sim $2-3x lower than theoretical values, agreement for other transitions is more satisfactory. For the W I line at 400.8 nm, we reported that our values of $\sim $100-200 were $\sim $5-10x larger than previously reported experimental data at electron temperature $>$ 10 eV [2]. Our recent measurements provide \textit{S/XB} $\sim $ 55 at higher electron density, where the geometrical loss flux from the plasma column is further reduced. Supported by the US DOE contract No. DE-FG02-07ER54912.\\[4pt] [1] A. Pospieszczyk et al., J. Phys. B \textbf{43}, 144017 (2010). [2] D. Nishijima et al., Phys. Plasmas \textbf{16}, 122503 (2009).