Simply digital recording and analysis technique for obtaining the phase shift and polarization rotation of a coherent beam passing through a magnetized plasma

Abstract Currently, one of the main interests of the plasma physics community that reproduces astrophysical scenarios on a laboratory scale is the characterization of the magnetization and dynamics of plasmas. Due to its advantages in spatial resolution, the Faraday rotation technique is one of the most widely used techniques for characterizing the magnetic field within the plasma. However, the technique requires knowledge of the density map along the direction of the scene beam, which imposes the challenge of implementing simultaneous interferometric and polarimetric setups, along with additional reference recordings. This manuscript proposes a digital recording interferometric setup, in addition to a digital processing and analysis technique, based on two simultaneous digital interferometric recording, with which information on phase shift and the polarization rotation angle of a coherent beam passing through a magnetized plasma can be obtained. The reconstruction technique for the interferometric phase and the polarogram proposed here is independent of the wavefront intensities in each arm of the interferometer, thus eliminating the need for a second exposure without the influence of the magnetized plasma. The technique is digitally tested with simulated wavefronts, where the scene beam passes through a plasma column, as expected in the pinch phase of a plasma focus discharge of a few hundred joules. In this way, the results allow us to evaluate the application of the technique in small PF discharges, with currents around 100 kA and plasma column diameters of sub-millimeter size.