Spectroscopic observation of Si I- and Si II-emission lines in the boundary of TEXTOR and comparison with kinetic calculations

Measurements of Si I- and Si II-emission lines were performed in the front of a test limiter under two different conditions: (i) silicon is sputtered from a silicon layer deposited on a graphite test limiter, (ii) silane is puffed into the plasma through a gas inlet in the limiter head, setting Si-atoms free from the dissociation of SiD(4) molecules. It was shown that the relative intensities of the emission lines within the multiplets are in good agreement with theoretical data calculated in the SL-coupling scheme. The values for 'ionization per photon' were calculated for the electron temperature range below 100 eV using the GKU kinetic code and compared with measured ones. The measured and theoretical values for the Si II-emission lines are in reasonable agreement within a deviation of 30%. It was found that experimentally measured values for Si I lines match the calculated ones only when a LTE-population of 3p(2) SL terms ((3)P, (1)D and (1)S) is assumed.