Effects of departures from LS coupling and configuration mixing on the Zeeman splitting and polarization of magnetic dipole radiation.

Abstract

In high-temperature magnetically confined plasmas, the individual Zeeman components of electric and magnetic dipole transitions in multiply charged atomic ions are usually not spectroscopically resolvable on account of the dominance of the Doppler broadening due to the thermal motion of the radiating ions. However, it is possible to measure the shift of the blended circularly polarized components from the position of the unshifted line. In the weak-magnetic-field regime, this average shift is linearly proportional to the magnetic field strength and to a Zeeman-splitting parameter. Simple expressions for this parameter have been derived which involve only the g factors for the upper and lower levels and their total electronic-angular-momentum quantum numbers. These expressions are valid for both electric and magnetic dipole transitions. With use of relativistic multiconfiguration wave functions, the Zeeman-splitting parameters have been evaluated for magnetic dipole transitions between the fine-structure levels of the ground-state configuration in carbonlike ions with even values of the nuclear charge from Z=22 to Z=30. A discussion is presented on the feasibility of determining local magnetic fields in magnetically confined plasmas from the analysis of the Zeeman splitting and polarization of the magnetic dipole radiation emitted by multiply charged atomic ions. In particular, it may be possible to determine the poloidal magnetic field in a tokamak plasma by observing the circularly polarized radiation emitted in a direction perpendicular to the precisely known toroidal field. It may also be possible to employ Zeeman-splitting and polarization measurements to determine the magnetic field distributions which are known to be associated with regions of solar activity, e.g., solar flares.