We demonstrate a laser wakefield accelerator with a novel electron injection scheme resulting in enhanced stability, reproducibility, and ease of use. In order to inject electrons into the accelerating phase of the plasma wave, a sharp downward density transition is employed. Prior to ionization by the laser pulse this transition is formed by a shock front induced by a knife edge inserted into a supersonic gas jet. With laser pulses of 8 fs duration and with only 65 mJ energy on target, the accelerator produces a monoenergetic electron beam with tunable energy between 15 and 25 MeV and on average 3.3 pC charge per electron bunch. The shock-front injector is a simple and powerful new tool to enhance the reproducibility of laser-driven electron accelerators, is easily adapted to different laser parameters, and should therefore allow scaling to the energy range of several hundred MeV.

We report the generation of stable and tunable electron bunches with very low absolute energy spread ($\Delta E\approx 5\mathrm{MeV}$) accelerated in laser wakefields via injection and trapping at a sharp downward density jump produced by a shock front in a supersonic gas flow. The peak of the highly stable and reproducible electron energy spectrum was tuned over more than 1 order of magnitude, containing a charge of 1–100 pC and a charge per energy interval of more than $10\mathrm{pC}/\mathrm{MeV}$. Laser-plasma electron acceleration with Ti:sapphire lasers using this novel injection mechanism provides high-quality electron bunches tailored for applications.

We present a two-stage noncollinear optical parametric chirped-pulse amplification system that generates $7.9\mathrm{fs}$ pulses containing $130\mathrm{mJ}$ of energy at an $805\mathrm{nm}$ central wavelength and $10\mathrm{Hz}$ repetition rate. These $16\mathrm{TW}$ light pulses are compressed to within 5% of their Fourier limit and are carefully characterized by the use of home-built pulse diagnostics. The contrast ratio before the main pulse has been measured as ${10}^{-4}$, ${10}^{-8}$, and ${10}^{-11}$ at $t=-3.3\mathrm{ps}$, $t=-5\mathrm{ps}$, and $t=-30\mathrm{ps}$, respectively. This source allows for experiments in a regime of relativistic light–matter interactions and attosecond science.

We present an all-laser-driven, energy-tunable, and quasimonochromatic x-ray source based on Thomson scattering from laser-wakefield-accelerated electrons. One part of the laser beam was used to drive a few-fs bunch of quasimonoenergetic electrons, while the remainder was backscattered off the bunch at weakly relativistic intensity. When the electron energy was tuned from 17–50 MeV, narrow x-ray spectra peaking at 5–42 keV were recorded with high resolution, revealing nonlinear features. We present a large set of measurements showing the stability and practicality of our source.