MEASUREMENT AND COMPARISON WITH THEORY OF THE TEMPERATURE DEPENDENCE OF SATELLITE TO RESONANCE LINE RATIOS OF HELIUM-LIKE NICKEL FROM THE JET TOKAMAK
The line ratios of the intercombination line x, the dielectronic and inner shell satellite line t and the n >= 3 dielectronic satellite lines to the resonance line w in the spectrum of helium-like nickel are measured with a high resolution X-ray crystal spectrometer on the JET tokamak. The central electron temperatures for which the spectra are taken range from about one third to twice the threshold energy for the line excitation. The measurements are compared with predictions from a model, taking into account the spatial emission profiles of the different ionisation stages of nickel calculated from the radial profiles of JET plasma parameters. The rate-coefficients for the formation of excited states are taken from a single, self consistent source of calculations of dielectronic and radiative recombination and electron impact excitation. The rate-coefficients for the calculation of the ionisation balance are critically reviewed. Good agreement is found for the ratios t/w and (n >= 3)/w, but for x/w significant disagreement is found. It is concluded that the present coronal equilibrium model correctly describes the ionisation balance, the radiative and dielectronic recombination and the electron impact excitation of electric dipole transitions, but that there is a problem with the excitation of non-dipole transitions.
Bibliographic Reference: REPORT: JET-P(89)67 EN (1989) AVAILABLE FROM THE PUBLICATIONS OFFICER, JET JOINT UNDERTAKING, ABINGDON, OXON. OX14 3EA (GB)
Record Number: 1989128068600 / Last updated on: 1990-10-01
Available languages: en