Contributions from ion-atom charge exchange collisions to the C VI Lyman series intensities in the JET tokamakFunded under: FP1-FUSION 9C
In the multi-keV temperature deuterium plasma such as in JET (Joint European Torus), C VI emission arises from excitation processes which in the absence of neutral hydrogen beam heating, occur near the plasma boundary. Distortions to the C VI Lyman decrement, such as the Ly beta/gamma/delta ratio and enhancement of high series members (around 1s-12p) are observed. In this circumstance, large influxes of D(0) atoms are anticipated at the plasma boundary, when the plasma is limited by the carbon innerwall. The intensities of the Lyman series members are interpreted in terms of electronic excitation of C(5+) ions in their ground state as well as charge-exchange collisions between C(6+) ions and thermal D(0) atoms, either in their ground state or in their excited states. The line-of-sight emission is modelled using an impurity ion transport code based on experimental electron temperature, electron density and D(0) radial profiles. Comparison of the observed relative intensities of the C VI Lyman series Ly beta/gamma/delta with the model calculations allows plausible corrections to be made to the effective charge-exchange rate coefficients as a function of the principal quantum number. The observations offer a potential method of measuring local D(0) concentrations near the boundary in high temperature, high D(0) recycling plasmas.
Bibliographic Reference: Report: JET-P(89)06 EN (1989)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 198910758 / Last updated on: 1994-12-01
Original language: en
Available languages: en