Intense proton acceleration in ultrarelativistic interaction with nanochannels

We show that both the flux and the cutoff energy of protons accelerated by ultraintense lasers can besimultaneously increased when using targets consisting of thin layers of bundled nanochannels. Particle-in-cellsimulations suggest that the propagation of an electromagnetic field in the subwavelength channels occurs viaexcitation of surface plasmon polaritons that travel in the channels down to the end of the target, sustainingcontinuous and efficient electron acceleration and boosting acceleration of protons via enhancement of the targetnormal sheath acceleration mechanism.