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Spectra in the visible range may be obtained along multiple lines of sight directed at the axisymmetric poloidal divertor of the Joint European Torus (JET) tokamak. In X-point magnetic field configurations, the scrape-off-layer plasma contacts the divertor target plates. Observations and analysis of diatomic spectra were conducted in the divertor plasma along lines of sight in the strike zone vicinity. CD, C(2) and BeD have been identified unambiguously. Synthetic spectra have been calculated. In addition to identification of the molecular features and separation of overlapping atomic lines, the comparison of simulations and observations allow quite sensitive determination of rotational and vibrational temperatures for the above diatomics in a divertor fusion plasma. Systematic studies show that rotational temperature (T(r)) and vibrational temperature (T(v)) are comparable for BeD but T(v) is significantly less than T(r) for CD and C(2). The BeD spectrum time history during a pulse appears as localized emission from the strike points similar to that of the atomic BeI visible spectrum lines. On the other hand, the CD bands during a swept pulse indicate a more distributed source. Thus both the BeD spectrum and time history suggest physical sputtering of BeD at the strike points. In contrast the CD spectrum and time history indicate chemical release of higher deuterides followed by catabolism to CD. This work constitutes the first detailed study of diatomic species in the JET tokamak.

Additional information

Authors: DUXBURY G, University of Strathclyde, Department of Physics and Applied Physics, Glasgow (GB);STAMP M F, ;SUMMERS H P,
Bibliographic Reference: Report: JET-P (97) 18 EN (1997) 11pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199711335 / Last updated on: 1997-10-16
Original language: en
Available languages: en