MeV Electron Acceleration at 1 kHz with <10 mJ Laser Pulses

We demonstrate laser-driven acceleration of electrons to MeV-scale energies at 1 kHz repetition rate using  <10 mJ pulses focused on near-critical density He and H2 gas jets. Using the H2 gas jet, electron acceleration to  ∼0.5 MeV in  ∼10 fC bunches was observed with laser pulse energy as low as 1.3 mJ. Increasing the pulse energy to 10 mJ, we measure  ∼1 pC charge bunches with  >1 MeV energy for both He and H2 gas jets.