Optimized setups for detection of Megatesla-level magnetic fields through Faraday rotation of XFEL beams

Abstract

A solid density target irradiated by a high-intensity laser pulse can become relativistically transparent, which then allows it to sustain an extremely strong laser-driven longitudinal electron current. The current generates a filament with a slowly-varying MT-level azimuthal magnetic field that has been shown to prompt efficient emission of multi-MeV photons in the form of a collimated beam required for multiple applications. This work examines the feasibility of using an x-ray beam from the European XFEL for the detection of the magnetic field via the Faraday rotation. Post-processed 3D particle-in-cell simulations show that, even though the relativistic transparency dramatically reduces the rotation in a uniform target, the detrimental effect can be successfully reversed by employing a structured target containing a channel to achieve a rotation angle of $10^{-4}$ rad. The channel must be relativistically transparent with an electron density that is lower than the near-solid density in the bulk. The detection setup has been optimized by varying the channel radius and the focusing of the laser pulse driving the magnetic field. We predict that the Faraday rotation can produce $10^3$ photons with polarization orthogonal to the polarization of the incoming 100 fs long probe beam with $5\times 10^{12}$ x-ray photons. Based on the calculated rotation angle, the polarization purity must be much better than $10^{-8}$ in order to detect the signal above the noise level.

References in corpus (9)

• Ultra-high brilliance multi-MeV $\gamma$-ray beam from non-linear Thomson scattering
• Highly-efficient source of collimated multi-MeV photons driven by radiation reaction of an electron beam in a self-generated magnetic field
• Pair creation in collision of $\gamma$--ray beams produced with high intensity lasers
• Measurement of Magnetic-Field Structures in a Laser-Wakefield Accelerator
• Leveraging extreme laser-driven magnetic fields for gamma-ray generation and pair production
• Faraday Conversion and Rotation In Uniformly Magnetized Relativistic Plasmas
• Propagation Effects in Magnetized Transrelativistic Plasmas
• Loading Relativistic Maxwell Distributions in Particle Simulations
• Exploring the accretion model of M87 and 3C 84 with the Faraday rotation measure observations

Cited by in corpus (8)

• Collimated gamma-ray beams from structured laser-irradiated targets -- how to increase the efficiency without increasing the laser intensity
• Relativistic laser driven electron accelerator using micro-channel plasma targets
• Forward sliding-swing acceleration: electron acceleration by high-intensity lasers in strong plasma magnetic fields
• Retrieving transient magnetic fields of ultrarelativistic laser plasma via ejected electron polarization
• Energy gain by laser-accelerated electrons in a strong magnetic field
• Thermonuclear Fusion Triggered by Collapsing Standing Whistler Waves in Magnetized Overdense Plasmas
• Deciphering in situ electron dynamics of ultrarelativistic plasma via polarization pattern of emitted gamma photons
• Relativistically transparent magnetic filaments: scaling laws, initial results and prospects for strong-field QED studies