Production Of High-quality Electron Beams Research Articles

Direct electron acceleration in plasma waveguides for compact high-repetition-rate x-ray sources

Numerous applications in fundamental and applied research, security, and industry require robust, compact sources of x-rays, with a particular recent interest in monochromatic, spatially coherent, and ultrafast x-ray pulses in well-collimated beams. Such x-ray sources usually require production of high-quality electron beams from compact accelerators. Guiding a radially polarized laser pulse in a plasma waveguide has been proposed for realizing direct laser acceleration (DLA), where the electrons are accelerated by the axial electric field of a co-propagating laser pulse (Serafim et al 2000 IEEE Trans. Plasma Sci. 28 1190). A moderate laser peak power is required for DLA when compared to laser wakefield acceleration, thus offering the prospect for high repetition rate operation. By using a density-modulated plasma waveguide for DLA, the acceleration distance can be extended with pulse guiding, while the density-modulation with proper axial structure can realize the quasi-phase matching between the laser pulses and electrons for a net gain accumulation (York et al 2008 Phys. Rev. Lett. 100 195001; York et al 2008 J. Opt. Soc. Am. B 25 B137; Palastro et al 2008 Phys. Rev. E 77 036405). We describe the development and application of a test particle model and particle-in-cell model for DLA. Experimental setups designed for fabrication of optically tailored plasma waveguides via the ignitor-heater scheme, and for generation and characterization of radially polarized short pulses used to drive DLA, are presented.

PIC simulations of the production of high-quality electron beams via laser–plasma interaction

We present some numerical studies and parameter scans performed with the electromagnetic, relativistic, fully self-consistent Particle-In-Cell (PIC) code ALaDyn (Acceleration by LAser and DYNamics of charged particles), concerning the generation of a low emittance, high charge and low momentum spread electron bunch from laser–plasma interaction in the Laser WakeField Acceleration (LWFA) regime, in view of achieving beam brightness of interest for FEL applications.

Production of high-quality electron bunches by dephasing and beam loading in channeled and unchanneled laser plasma accelerators

High-quality electron beams, with a few 109 electrons within a few percent of the same energy above 80 MeV, were produced in a laser wakefield accelerator by matching the acceleration length to the length over which electrons were accelerated and outran (dephased from) the wake. A plasma channel guided the drive laser over long distances, resulting in production of the high-energy, high-quality beams. Unchanneled experiments varying the length of the target plasma indicated that the high-quality bunches are produced near the dephasing length and demonstrated that channel guiding was more stable and efficient than relativistic self-guiding. Consistent with these data, particle-in-cell simulations indicate production of high-quality electron beams when trapping of an initial bunch of electrons suppresses further injection by loading the wake. The injected electron bunch is then compressed in energy by dephasing, when the front of the bunch begins to decelerate while the tail is still accelerated.

Publisher’s Note: Production of high-quality electron beams in numerical experiments of laser wakefield acceleration with longitudinal wave breaking [Phys. Rev. ST Accel. Beams6, 121301 (2003)

Publisher’s Note: Production of high-quality electron beams in numerical experiments of laser wakefield acceleration with longitudinal wave breaking [Phys. Rev. ST Accel. Beams<b>6</b>, 121301 (2003)

Production of high-quality electron beams in numerical experiments of laser wakefield acceleration with longitudinal wave breaking

In 1998 Bulanov et al. [Phys. Rev. E 58, R5257 (1998)] proposed a novel scheme for the production of high-quality electron beams in laser wakefield acceleration in which a controlled longitudinal nonlinear wave breaking is induced by a tailored electron density profile. This proposal was supported by both analytical and numerical results in a spatially one-dimensional configuration. In this paper we present results of a particle-in-cell simulation, two-dimensional in space and three-dimensional in the fields, of the interaction of an ultraintense laser pulse with a preformed plasma where the electron density decreases steeply from a first to a second plateau. We show that in our regime two-dimensional effects play a relevant role, allowing the production of well collimated, short and almost monochromatic electron beam. Remarkably low values of transverse and longitudinal normalized beam emittance ${ϵ}_{\mathrm{rms}}^{\mathrm{tr}}=9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}\text{ }\mathrm{mm}\text{ }\mathrm{mrad}$ and ${ϵ}_{\mathrm{rms}}^{\mathrm{lon}}=2\text{ }\mathrm{mm}\text{ }\mathrm{keV}$ are obtained.