Magnetic field generation in plasma waves driven by co-propagating intense twisted lasers

Shi, Y. and Vieira, J. and Trines, R. M. G. M. and Bingham, R. and Shen, B.F. and Kingham, R. J. (2018) Magnetic field generation in plasma waves driven by co-propagating intense twisted lasers. Physical Review Letters, 121 (14). ISSN 0031-9007

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    Abstract

    We present a new magnetic field generation mechanism in underdense plasmas driven by the beating of two, co-propagating, Laguerre-Gaussian (LG) orbital angular momentum (OAM) laser pulses with different frequencies and also different twist indices. The resulting twisted ponderomotive force drives up an electron plasma wave with a helical rotating structure. To second order, there is a nonlinear rotating current leading to the onset of an intense, static axial magnetic field, which persists over a long time in the plasma (ps scale) after the laser pulses have passed by. The results are confirmed in three-dimensional particle-in-cell simulations and also theoretical analysis. For the case of 300 fs duration, 3.8×1017 W/cm2 peak laser intensity we observe magnetic field of up to 0.4 MG. This new method of magnetic field creation may find applications in charged beam collimation and microscale pinch.