Betatron x-ray generation from electrons accelerated in a plasma cavity in the presence of laser fields

Abstract

X-ray generation by many charged particles experiencing accelerations similar to those in laser wakefield accelerator experiments, including the effects of the interaction of the laser pulse with trapped electrons, as well as betatron oscillations in an electron cavity, is directly evaluated. Semianalytic calculations of high energy photons are performed by solving classical spectral integrals for x rays produced by the combined action of a laser pulse and the fields of an electron cavity in an underdense plasma. Angularly resolved power spectra for electron bunches accelerated in the combined electromagnetic fields due to a Gaussian laser field and a paraboloid potential due to an electron cavity are calculated using a semianalytic numerical algorithm to explicitly calculate the well known spectral integrals. The laser polarizes the resulting x-ray radiation. In addition to the high energy photons due to the betatron oscillations, lower energy radiation is emitted in a conical emission pattern due to the coherent addition of radiation from the linear acceleration of the electrons in the wakefield.