90 / 2023-04-13 13:42:06

Efficient generation of axial magnetic field by multiple laser beams with twisted pointing directions

self-generated magnetic field

极端光下的基础物理学 > 基础物理-I

Strong laser-driven magnetic fields are crucial for high-energy-density and laboratory astrophysics research, but generation of axial multi-kT fields remains a challenge. The difficulty comes from the inability of a conventional linearly polarized laser beam to induce the required azimuthal current or, equivalently, angular momentum (AM). We show that several laser beams can overcome this difficulty. Our three-dimensional kinetic simulations demonstrate that a twist in their pointing direction enables them to carry orbital AM and transfer it to the plasma, thus generating a hot electron population carrying AM needed to sustain the magnetic field. The resulting multi-kT field occupies a volume that is tens of thousands of cubic microns and it persists on a ps time scale. The mechanism can be realized for a wide range of laser intensities and pulse durations.  Our scheme is well-suited for implementation using multi-kJ PW-class lasers, because, by design, they have multiple beamlets and because the scheme requires only linear-polarization.