On the measurement of molecular particle fluxes in fusion boundary plasmas

This paper describes the determination of the molecular deuterium particle flux Gamma(M) by means of Fulcher-alpha-band spectroscopy. As previous investigations have shown [1], the measurement of the molecular flux is essential for an accurate determination of the total deuterium flux released from carbon plasma-facing components. Experiments have been carried out to ascertain the number of deuterium molecules released from a test limiter in the plasma edge of TEXTOR. For different plasma conditions, a molecular flux up to Gamma(M) similar or equal to 5 x 10(20) s(-1) was measured. Fulcher-alpha-band spectroscopy is introduced as a straightforward method for the determination of Gamma(M). We describe photon flux measurements, a comparison with Eirene calculations, and finally the determination of recycling particle fluxes. The conversion factor D/XB taken from a collisional-radiative model (CRMOL) and relating the number of molecular losses per photon was verified in gas injection experiments. (C) 2003 Elsevier Science B.V. All rights reserved