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Updated: Feb 3, 2026

Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Magnetic Field Generation in Plasma Waves Driven by Copropagating Intense Twisted Lasers
Y Shi1, J Vieira2, R M G M Trines3
1Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
Abstract:
We present a new magnetic field generation mechanism in underdense plasmas driven by the beating of two, copropagating, Laguerre-Gaussian orbital angular momentum 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, 3.8×10^{17} W/cm^{2} 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.
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