Ultrashort high energy electron bunches from tunable surface plasma waves driven with laser wavefront rotation

We propose to use ultra-high intensity laser pulses with wavefront rotation (WFR) to produce short, ultra-intense surface plasma waves (SPW) on grating targets for electron acceleration. Combining a smart grating design with optimal WFR conditions identified through simple analytical modeling and particle-in-cell simulation allows to decrease the SPW duration (down to few optical cycles) and increase its peak amplitude. In the relativistic regime, for $I\lambda_0^2=3.4 \times 10^{19}{\rm W/cm^2\mu m^2}$, such SPW are found to accelerate high-charge (few 10's of pC), high-energy (up to 70 MeV) and ultra-short (few fs) electron bunches.