Measuring laser-driven 100-Tesla scale magnetic fields with an oblique Faraday probe

Recent advances in optics manufacturing has enabled post-compression mode conversion of high-power and high-intensity laser systems allowing experimental access to Laguerre-Gaussian modes at relativistic intensities. As a result, we are beginning to see experimental results of various laser-plasma interactions when driven by higher—order laser modes that can carry an orbital angular momentum (OAM). Current and upcoming experiments with OAM beams have covered a wide variety of regimes including wakefield acceleration, solid target interactions, and laser-plasma instabilities.

In this work, we will present recent experimental results from the COMET laser at LLNL which was mode converted to a L=1 OAM beam and focused to a relativistic intensity Laguerre Gaussian mode. This was able to drive a ring-like plasma channel that was magnetized both azimuthally and axially. A 1w probe beam at an oblique angle of incidence was used to characterize this magnetic field via Faraday rotation. These measurements are compared to large-scale 2.5D PIC calculations and theory showing good agreement.