Petawatt-laser-driven wakefield acceleration of electrons to 2 GeV in 10¹⁷ cm⁻³ plasma Free

Electron self-injection into a laser-plasma accelerator (LPA) driven by the Texas Petawatt (TPW) laser is reported at plasma densities 1.7 - 6.2 × 10¹⁷ cm⁻³. Energy and charge of the electron beam, ranging from 0.5 GeV to 2 GeV and tens to hundreds of pC, respectively, depended strongly on laser beam quality and plasma density. Angular beam divergence was consistently around 0.5 mrad (FWHM), while shot-to-shot pointing fluctuations were limited to ±1.4 mrad rms. Betatron x-rays with tens of keV photon energy are also clearly observed.