Shot-to-shot electron beam pointing instability in a nonlinear plasma bubble.

Shot-to-shot electron beam pointing instability in the plasma bubble, defined here as electron beam pointing jitter (EBJ), is a long-standing problem that limits the potential of the laser wakefield accelerator (LWFA) in a range of demanding applications. In general, EBJ is caused by variations in laser and plasma parameters from shot to shot, although the exact physical mechanism by which EBJ grows in the plasma wave remains unclear. In this work we theoretically investigate the fundamental physics of EBJ inside the plasma bubble and show how the intrinsic betatron oscillation can act as an amplifier to enhance EBJ growth.

Accelerating Ions by Crossing Two Ultraintense Lasers in a Near-Critical Relativistically Transparent Plasma.

A new scheme of ion acceleration by crossing two ultraintense laser pulses in a near-critical relativistically transparent plasma is proposed. One laser, acting as a trigger, preaccelerates background ions in its radial direction via the laser-driven shock. Another crossed laser drives a comoving snowplow field which traps some of the preaccelerated ions and then efficiently accelerates them to high energies up to a few giga-electron-volts.

Optimizing Laser Pulses for Narrow-Band Inverse Compton Sources in the High-Intensity Regime.

Scattering of ultraintense short laser pulses off relativistic electrons allows one to generate a large number of X- or gamma-ray photons with the expense of the spectral width-temporal pulsing of the laser inevitable leads to considerable spectral broadening. In this Letter, we describe a simple method to generate optimized laser pulses that compensate the nonlinear spectrum broadening and can be thought of as a superposition of two oppositely linearly chirped pulses delayed with respect to each other. We develop a simple analytical model that allows us to predict the optimal parameters of such a two-pulse-the delay, amount of chirp, and relative phase-for generation of a narrow-band γ-ray spectrum.

Higher-Dimensional Caustics in Nonlinear Compton Scattering.

A description of the spectral and angular distributions of Compton scattered light in collisions of intense laser pulses with high-energy electrons is unwieldy and usually requires numerical simulations. However, due to the large number of parameters affecting the spectra such numerical investigations can become computationally expensive. Using methods of catastrophe theory we predict higher-dimensional caustics in the spectra of the Compton scattered light, which are associated with bright narrow-band spectral lines, and in the simplest case can be controlled by the value of the linear chirp of the pulse.