Magnetic Field of a Plasma Wake Driven by a Laser Pulse

Abstract

The quasistatic magnetic field generated by a short laser pulse in a uniform rarefied plasma is found analytically and compared to two-dimensional particle-in-cell simulations. It is shown that in a frame moving with the pulse the magnetic field contains a component which is homogeneous in the longitudinal direction and a component which is oscillating at the wave number ${2k}_p$, where $k_p$ is the wave number of the plasma wake. Particle simulations confirm the analytical results and are also used to treat the case of high intense laser pulses with $v_E/c\gtrsim 1$. The resultant magnetic field has a focusing effect on relativistic electrons in the plasma wakefield accelerator context.