Production of high-angular-momentum electron beams in laser-plasma interactions

Abstract

It was shown that in the interactions of ultra-intense circularly polarized laser pulse with the near-critical plasmas, the angular momentum can be transferred efficiently from the laser beam to electrons through the resonance acceleration process. The transferred angular momentum increases almost linearly with the acceleration time t_{a} when the electrons are resonantly accelerated by the laser field. In addition, it is shown analytically that the averaged angular momentum of electrons is proportional to the laser amplitude a_{L}, and the total angular momentum of the accelerated electron beam is proportional to the square of the laser amplitude a_{L}^{2} for a fixed parameter of n_{e}/n_{c}a_{L}. These results are verified by three-dimensional particle-in-cell simulations. This regime provides an efficient and compact alternative for the production of high angular momentum electron beams, which may have many potential applications in condensed-matter spectroscopy, new electron microscopes, and bright x-ray vortex generation.

Manipulating the topological structure of ultrarelativistic electron beams using Laguerre–Gaussian laser pulse

“…In this case, the resonant electrons in the plasma bubble are locked in the acceleration phase of CP laser field and they experience circular motions collectively together with the rotating CP laser field. As a result, the energy density of the accelerated electron beam exhibits an annular distribution, as shown in figure 2(a), which also agrees well with previous simulation results using CP Gaussian laser pulse [17,45]. However, for l 0 ¹ , the results are quite different from the case with l=0.…”

“…When l=0, the OAM of the LG laser is zero, but the CP laser pulse itself still carries spin angular momentum. In this case, the accelerated electrons can still gain angular momentum from the laser pulse [17]. In the simulations, the conversion rate of the angular momentum from laser to electrons is about 30% for these three cases, which is comparable with the energy conversion rate.…”

“…In this process, the trapped electrons are microbunched with the laser wavelength, as shown figure 1(d), which is indicative of direct laser acceleration (DLA) [47]. By directly interacting with the laser field, the electrons gain energy and angular momentum (both spin and orbit angular momentum) simultaneously from the LG laser pulse [17], as a result, they are manipulated by the laser pulse and distributed as helical structures, as indicated in figure 1(d).…”

“…They are widely used in applications such as optical microscopy, micromanipulation, quantum information, astronomy, etc [6][7][8][9][10]. Recently, vortex laser pulses with relativistic intensities are also achieved based on the techniques of plasma holograms [11], Raman amplification [12], and the light fan [13], which have stimulated much research interest in intense laser-matter interactions and extended the study of OAM into a relativistic regime [14][15][16][17][18].…”

Generation of GeV positron and γ-photon beams with controllable angular momentum by intense lasers

“…For long time ago, it was realized that the circularly-polarized (CP) light beam might behavior like an optical torque [30], the spin angular momentum (SAM) of photons of such light can be transferred to the BAM of particles [31,32]. As the light intensity increases, this effect could be significant via laser-driven electron acceleration [27,33] and subsequent photon emission [28,34,35]. However, to the best of our knowledge, it has not yet been reported so far on how to obtain high-energy dense positron and γ-photon beams with a highly controllable angular momentum at currently affordable laser intensities.…”