Spectral characterization of fully phase-matched high harmonics generated in a hollow waveguide for free-electron laser seeding
Abstract
A bright high harmonic source is presented delivering up to 10^10 photons per second around a central photon energy of 120 eV. Fully phase matched harmonics are generated in an elongated capillary reaching a cut-off energy of 160 eV. The high HHG photon fluence opens new perspectives towards seeding free electron lasers at shorter wavelengths than the state of the art. Characterization of the phase matching conditions in the capillary is presented.