Laser-cluster interaction in an external magnetic field: the effect of laser polarization

Abstract

Collisionless absorption of laser energy by an electron via laser-cluster interaction in an ambient magnetic field ($B_0$) has recently renewed interest. %due to high levels of absorption. Previously, using a rigid sphere model (RSM) and an extensive particle-in-cell (PIC) simulation with linearly polarized (LP) laser light, we have shown that an auxiliary field $B_0$ in a transverse direction to the laser polarization significantly enhances the laser absorption [Scientific Reports {\bf 12}, 11256 (2022)]. In this LP case, the average energy ($\mathcal{E}_A$) of an electron rises near $30-70$ times of its ponderomotive energy ($U_p$). The two-stage laser absorption by cluster electrons has been attributed via anharmonic resonance (AHR) followed by electron-cyclotron resonance (ECR) satisfying the improved phase-matching and frequency-matching conditions simultaneously. %Again, we report the narrow cone-like propagation of these %energetic electron bunches as a weakly relativistic electron beam with an %angular spread $\Delta\theta<5^{\circ}$. %Also, we highlight the effect of bigger cluster sizes on the energy and %angular spread of these electrons. In the present work, we study the effect of circularly polarized (CP) laser fields on the cluster-electron dynamics considering left/right circular polarizations with an ambient $B_0$. %, energy distribution, and..