New method for polarization measurements of magnetic fields in dense plasmas

Measurements of magnetic fields based on observations of the Zeeman splitting ω_B of spectral lines is a virtually impossible task in dense plasmas of powerful Z-pinches where the Stark splitting in the ion microfields ω_F is much greater than ω_B. In this situation, much better diagnostics of magnetic fields can be achieved through polarization difference contours obtained by subtracting profiles of the same spectral line observed in two orthogonal linear polarizations. In this way the obscuring role of the Stark effect is significantly diminished. In the present paper it is shown that the most sensitive and accurate measurements of the magnitude and the direction of the magnetic field in a dense plasma can be conducted employing central Stark components of hydrogen or hydrogen-like spectral lines. The polarization contour of a central Stark component turned out to be much more sensitive to the magnetic field than the polarization contour of a lateral component of the same line, namely by a factor of (ω_F/ω_B) ³≫1. This constitutes a drastic enhancement of the previously suggested method that had used the polarization contour of a lateral Stark component because in dense plasmas a typical value of the above factor is (ω_F/ω_B)³⩾10³ . The new method can also be used for laser fusion plasmas and for some astrophysical objects such as magnetic white dwarfs