Compact X-ray sources offering high-brightness radiation for advanced imaging applications are highly desired. We investigate, analytically and numerically, the photon yield of superradiant inverse Compton scattering from microbunched slectrons in the linear Thomson regime, using a classical electrodynamics approach. We show that for low electron beam energy, which is generic to inverse Compton sources, the single electron radiation distribution does not match well to collective amplification pattern induced by a density modulated electron beam. Consequently, for head-on scattering from a visible laser, the superradiant yield is limited by the transverse size of typical electron bunches driving Compton sources. However, by simultaneously increasing the electron beam energy and introducing an oblique scattering geometry, the superradiant yield can be increased by orders of magnitude.

Operation of a Quantum Free Electron Laser (QFEL) could provide a compact and fully coherent source of X- and γ-rays. Imperative to experimental realization is allowing for decoherence effects of either spontaneous emission or space-charge to take place, having opposing constraints. Here, for the first time, we present a one-dimensional QFEL Wigner model that includes longitudinal space-charge effects by quantizing the periodic potential derived from the Fourier components of the longitudinal electron beam density. The model is used to investigate steady-state QFEL gain and momentum state dynamics for a variety of space-charge regimes. We find increased saturation lengths and lower saturation intensity as a result of attenuated transitions in the two-level quantum system. In addition, we characterize a space-charge regime where specific transitions outside the QFEL bandwidth are targeted, such that the conventional description breaks down. These findings serve as a consistent theoretical extension of existing QFEL models.

Time-resolved investigation of electron dynamics relies on the generation of isolated attosecond pulses in the (soft) X-ray regime. Thomson scattering is a source of high energy radiation of increasing prevalence in modern labs, complementing large scale facilities like undulators and X-ray free electron lasers. We propose a scheme to generate isolated attosecond X-ray pulses based on Thomson scattering by colliding microbunched electrons on a chirped laser pulse. The electrons collectively act as a relativistic chirped mirror, which superradiantly reflects the laser pulse into a single localized beat. As such, this technique extends chirped pulse compression, developed for radar and applied in optics, to the X-ray regime. In this paper we theoretically show that, by using this approach, attosecond soft X-ray pulses with GW peak power can be generated from pC electron bunches at tens of MeV electron beam energy. While we propose the generation of few cycle X-ray pulses on a table-top system, the theory is universally scalable over the electromagnetic spectrum.

Electron bunches from a photoionized ultracold atomic gas enable the generation of spatially coherent soft-X-ray pulses trough inverse Compton scattering. Combined with at source prebunching, a compact, fully coherent soft X-ray source is proposed.