In this article, the concept of a recently funded R project for installation proof-of-concept cavity-based x-ray free electron laser (CBXFEL) demonstrator experiment at European XFEL facility is presented, with first results expected in 2024. It composed an cavity design backscattering geometry 133 m round trip length using cryogenically cooled diamond crystals. employs retroreflection to reduc...

The interaction of a laser-produced electron beam with an ultraintense laser pulse in free space is studied. We show that the optical pulse with a(0)=0.5 imparts momentum to the electron beam, causing it to deflect along the laser propagation direction. The observed 3-degree angular deflection is found to be independent of polarization and in good agreement with a theoretical model for the inte...

A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded free-electron laser to produce amplified, longitudinally coherent, Fourier transform-limited output at a harmonic of the seed laser. A seed carbon dioxide laser at a wavelength of 10.6 micrometers produced saturated, amplified free-etectron laser output at the second-harmonic wavelength, 5.3 mi...

In recent years laser light has been used to control the motion of electron waves. Electrons can now be diffracted by standing waves of light. Laser light in the vicinity of nanostructures is used to affect free electrons, for example, femto-second and atto-second laser-induced electrons are emitted from nanotips delivering coherent fast electron sources. Optical control of dispersion of the em...