Ultrahigh-intensity optical slow-wave structure for direct laser electron acceleration

We report the development of corrugated slow-wave plasma guiding structures with application to quasi-phase-matched direct laser acceleration of charged particles. These structures support guided propagation at intensities up to 2x1017 W/cm2, limited at present by our current laser energy and side leakage. Hydrogen, nitrogen, and argon plasma waveguides up to 1.5 cm in length with a corrugation period as short as 35 μm are generated in extended cryogenic cluster jet flows, with corrugation depth approaching 100%. These structures remove the limitations of diffraction, phase matching, and material damage thresholds and promise to allow high-field acceleration of electrons over many centimeters using relatively small femtosecond lasers. We present simulations that show that a laser pulse power of 1.9 TW should allow an acceleration gradient larger than 80 MV/cm. A modest power of only 30 GW would still allow acceleration gradients in excess of 10 MV/cm