Direct Electron Acceleration with Radially Polarized Laser Beams

Abstract

In the past years, there has been a growing interest in innovative applications of radially polarized laser beams. Among them, the particular field of laser-driven electron acceleration has received much attention. Recent developments in high-power infrared laser sources at the INRS Advanced Laser Light Source (Varennes, Qc, Canada) allowed the experimental observation of a quasi-monoenergetic 23-keV electron beam produced by a radially polarized laser pulse tightly focused into a low density gas. Theoretical analyses suggest that the production of collimated attosecond electron pulses is within reach of the actual technology. Such an ultrashort electron pulse source would be a unique tool for fundamental and applied research. In this paper, we propose an overview of this emerging topic and expose some of the challenges to meet in the future.

Sensitiveness of axial magnetic field on electron acceleration by a radially polarized laser pulse in vacuum

“…These equations are not valid for a tightly focused laser pulse in its present form. Electron acceleration with a tightly focused RP laser pulse depends on a non paraxial approach for its accurate description [12,20,21]. The magnetic field components related to the laser pulse can easily be deduced through Maxwell's equation .…”

“…They presented that the field phase averaged energy is maximum under moderately tight focusing than extremely tight focusing due to optimal phase of laser field. Varin et al [21] presented broad overviews of longitudinal electron acceleration by a tightly focused laser pulse. They confirmed the direct acceleration of electron at rest by longitudinal electric field component can be done experimentally with a high power infrared laser source at the advanced laser light source (ALLS) facility.…”

Electromagnetic fields of an ultra-short tightly-focused radially-polarized laser pulse

“…(22) has been introduced specifically [15] to eliminate the frequency corresponding to k = −k 0 . An initial spectrum which involves only physical frequencies, to be employed next, is the Poissonian [28,29,33] …”

Favorable target positions for intense laser acceleration of electrons in hydrogen-like, highly-charged ions

“…Free electrons can be injected into the focal region of an intense laser beam, where they experience the strong electromagnetic field and are accelerated to MeV or even GeV energies. [12][13][14][15][16][17][18] Different schemes have been developed to transfer more energy to the electrons, as well as to reduce the angular divergence of the electron beams, such as those employing radially-polarized laser fields, [19][20][21][22][23][24][25] chirped pulses, [26][27][28][29][30][31][32][33] an additional magnetic field, [34][35][36] or a linearlypolarized Laguerre-Gaussian ("twisted") laser pulse. 37 In vacuum acceleration, it has been shown theoretically that the angular divergence of the accelerated electron beam can be narrowed by using either a radially-polarized laser pulse 24,25 or a linearly-polarized Laguerre-Gaussian laser pulse with orbital angular momentum l ¼ 62.…”