Zeeman splitting of laser-driven soft X-ray laser line by the enhancement of magnetic field in plasma

Kawachi, Tetsuya; Hasegawa, Noboru; Iwamae, Atsushi*; Yoneda, Hitoki*

Polarization is a fundamental property of light, and the effective use provides us powerful tools for probing materials and for plasma diagnostics. In plasmas, alignment of emission shows the plasma anisotropy, and Zeeman splitting informs us the magnetic field strength. We took the plasma-based soft X-ray laser as an example and observed the Zeeman splitting under the external magnetic field. A grazing incidence spectrograph, HIREFS, with the resolution of 15000 was used to observe the X-ray laser line. A magnetic coil driven by an electrical pulsed power supply provided the external magnetic field of 1035 T along the direction of the plasma column, and the left-handed and right-handed circular polarization components were obtained separately. The experimental result indicated that the magnetic field was larger by a factor of 4 than that of the applied field, which implied that the magnetic field compression occurred in the dynamics of the intense laser-plasma interaction.