Determination of magnetic fields based on the Zeeman effect in regimes inaccessible by Zeeman-splitting spectroscopy

We discuss the limits of applying spectroscopic methods for the determination of magnetic fields that are based on the Zeeman effect and allow for extending the field diagnostics to conditions in which the Zeeman-split pattern is not resolvable. We analyze the diagnostic limits in terms of the minimum magnetic field that can be determined for a given Lorentzian line-width. This form of analysis is useful since the Lorentzian profile corresponds to the Stark broadening of isolated spectral lines that is often the main mechanism of smearing out the Zeeman-split patterns in high-energy-density plasmas. The analysis is performed for the 2S–2P atomic system. It is shown that the curves that define the limits of the diagnostic methods in the magnetic-field Lorentzian-width plane, are linear for a wide range of parameters and can be obtained by employing simple expressions that are useful for planning experiments and diagnostic systems.