Faraday-Rotation Measurements of Megagauss Magnetic Fields Produced by the Zebra Z-Pinch Generator

摘要

Summary form only given. Experiments to be performed at the Nevada Terawatt Facility have applications related to laboratory astrophysics, radiation sources, and fusion research. Some of these experiments require megagauss magnetic fields in a vacuum environment for hot plasma confinement or stabilization. The ultrahigh magnetic fields required will be produced using Zebra, a fast Z-pinch generator. These magnetic fields will be measured using the Faraday effect. The Faraday effect is the rotation of the polarization plane of a light beam traveling through a Faraday-active material along the magnetic field. The amount of rotation observed is proportional to the magnitude of the magnetic field and the length of the Faraday-active material. The proportionality constant is called the Verdet constant. To make local magnetic field measurements, the setup for the Zebra experiments uses small disks (3 mm in diameter, 2.0plusmn0.1 mm thick) of flint glass. The types of flint glass used are F2 and SF6, with Verdet constants of 15 rad/(Tmiddotm) and 27 rad/(Tmiddotm) respectively, at 532 nm. These Verdet constants allow the setup to be sensitive to a broad range of field strengths, from 10 T to 300 T (0.1-3 MG). A beam produced by a 532 nm, 250 mW DPSS CW laser will first be polarized and then passed through a glass probe where the polarization plane of the beam will undergo a rotation based on the magnitude of the magnetic field, the type of glass used, and the length of the probe. The emerging beam will then arrive at an analyzer, which will split the beam into its perpendicular and parallel components. Each component will be monitored by a photodiode, in a differential setup. Progress made with this diagnostic setup shall be presented