Self-Guiding of Ultrashort, Relativistically Intense Laser Pulses through Underdense Plasmas in the Blowout Regime

Abstract

The self-guiding of relativistically intense but ultrashort laser pulses has been experimentally investigated as a function of laser power, plasma density, and plasma length in the blowout regime. The extent of self-guiding, observed by imaging the plasma exit, is shown to be limited by nonlinear pump depletion with observed self-guiding of over tens of Rayleigh lengths. Spectrally resolved images of the plasma exit show evidence consistent with self-guiding in the plasma wake. Minimal losses of the self-guided pulse resulted when the initial spot size was matched to the blowout radius.

Role of direct laser acceleration in energy gained by electrons in a laser wakefield accelerator with ionization injection

“…Only 73% of the electrons were evacuated resulting in a residual, on-axis plasma electron density of 2.1 x 10 18 cm -3 within the first bucket. The energy gain due to the wakefield is approximately linear with distance, and the maximum energy gain is limited by dephasing [6] and not pump depletion [33]. The maximum energy gain (black curve) of these electrons is 234 MeV, which occurs at 1440 µm into the plateau region of the plasma.…”

Role of Direct Laser Acceleration of Electrons in a Laser Wakefield Accelerator with Ionization Injection

“…Therefore, T p ∼ 1 indicates a significant overlap between the transverse laser field and the trapped electrons. In these experiments, T p ∼ 1, and with a 0 ∼ 2 and P ∼ 2-3P crit , the LWFA was operating in the near-complete blowout [23] and self-guided regime [35]. In this case, electron self-trapping does not occur until the laser pulse undergoes considerable longitudinal and transverse compression [36,37].…”

Pulsed mid-infrared radiation from spectral broadening in laser wakefield simulations

“…At low powers, preformed plasma channels can provide radial confinement and maintain the ponderomotive force. At higher powers, the radial expulsion of electrons initially focuses the pulse and can result in a transient self-guiding structure: relativistic self-focusing and guiding [10][11][12][13][14] . Additionally, the local reduction in group velocity accompanying the red-shifting compresses the pulse [15][16][17][18] .…”