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.
- magnetic field
- laser pulses
- electron plasma waves
Shi, Y., Vieira, J., Trines, R. M. G. M., Bingham, R., Shen, B. F., & Kingham, R. J. (2018). Magnetic field generation in plasma waves driven by co-propagating intense twisted lasers. Physical Review Letters, 121(14), . https://doi.org/10.1103/PhysRevLett.121.145002