High-Intensity Laser Evolution and Multi-GeV Electron Acceleration in Dark-Current-Free Laser Plasma Accelerators*

Future applications of laser-plasma accelerators will require one or more stages providing multi-GeV energy gain. To reach multi-GeV energies in a single accelerator stage, the high-intensity drive laser pulse must be kept focused over several tens of centimeters through a sufficiently low-density (10^17 cm^-3) plasma.  Without an external guiding mechanism, the laser will diffract reducing the laser intensity, which in turn limits acceleration to ~ 1 cm. Recently, hydrodynamic optical-field-ionized (HOFI) plasma channels [1-3] have gained attention because i) they produce tightly confined channels for n_0 ~ 10^17 cm^-3, and ii) contain no external structure making them ideal for > kHz operation. We demonstrate experimentally high intensity laser evolution in 30-cm-long HOFI plasma channels at the BELLA PW laser. We demonstrate conditions under which the channel can be tailored to match the drive laser focus in multi-GeV stages. Through controlled electron injection, we present example electron beams with single, quasimonoenegertic peaks up to 9.2 GeV and charge extending beyond 10 GeV.

[1] R. Shalloo et al., Phys. Rev. E (2018)

[2] A. Picksley et al., Phys. Rev. E (2020)

[3] L. Feder et al., Phys. Rev. Research (2020)