Pulse propagation and electron acceleration in a corrugated plasma channel

Abstract

A preformed plasma channel provides a guiding structure for laser pulses unbound by the intensity thresholds of standard waveguides. The recently realized corrugated plasma channel [Layer, Phys. Rev. Lett. 99, 035001 (2007)] allows for the guiding of laser pulses with subluminal spatial harmonics. These spatial harmonics can be phase matched to high energy electrons, making the corrugated plasma channel ideal for the acceleration of electrons. We present a simple analytic model of pulse propagation in a corrugated plasma channel and examine the laser-electron beam interaction. Simulations show accelerating gradients of several hundred MeV/cm for laser powers much lower than required by standard laser wakefield schemes.

Quasi-phase-matched acceleration of electrons in a corrugated plasma channel

“…We then conclude that the increase in transverse scattering for a 0 ¼ 0:25 as opposed to a 0 ¼ 0:1 is the combination of two effects: the quasi-phase-matched transverse force scales linearly with the pulse amplitude, and the electrostatic forces due to modifications in background plasma scale quadratically with pulse amplitude. The second effect was neglected in previous works [8,9].…”

“…To illustrate the principle of QPMA and find a scaling for energy gain, we consider a simple model presented by Palastro et al [8,9]. The radial component of the laser pulse vector potential in the plasma channel can be expressed in envelope form as follows:…”

Quasi-Phase-Matched Laser Wakefield Acceleration

“…Axial density modulated plasma waveguides have been developed [15] and explored for quasi-phasematched direct laser acceleration of electrons [16][17][18][19] and THz generation [20]. In an axially modulated plasma waveguide, the guided mode is composed of spatial harmonics whose associated phase velocities can be tuned through the modulation period.…”

Theory and simulation of quasi-phase matched acceleration of electrons in a corrugated plasma channel

“…Quasi-phase matching refers to matching the electron velocity to the phase velocity of an individual spatial harmonic comprising an electromagnetic wave propagating in an axially modulated structure. In the scheme described here, an electron beam co-propagating with a radially polarized laser pulse injected into a corrugated plasma waveguide is accelerated by a phase-matched axial spatial harmonic of the resulting guided electromagnetic field, providing linear energy gain over the interaction length [1]. In order to achieve linear energy gain over an extended interaction length, three things are required: slow electromagnetic waves (providing quasi-phase matching), a channel for guiding the laser pulse (eliminating diffractive spreading of the laser pulse) [2], and radial polarization (providing a component of electric field along the propagation axis) [1].…”

“…In this work we used the code TurboWAVE as the PIC simulation code [3]. The simulations are used to validate the simple theoretical model [1], examine the self-consistent electrostatic fields generated by the beam itself, and to conduct preliminary studies on density ramping for lowering the required injection energies in QPMA.…”