Stable, polarized betatron raditation: x-ray absorption spectroscopy in WDM unveiling ultrafast electron heating (Conference Presentation)

Betatron radiation from laser-plasma accelerators reproduces the principle of a synchrotron on a millimeter scale, but featuring femtosecond duration. Here we present the outcome of our latest developments, which now allow us to produce stable and polarized X-ray bursts. Moreover, the X-ray polarization can simply be adjusted by tuning the polarization of the laser driving the process. The excellent stability of the source is expressed in terms of pointing, flux, transverse distribution and critical energy of the spectrum. These combined features make our betatron source particularly suitable for applications in ultrafast X-ray science. In this presentation we will describe the generation process, relying on the ionization injection scheme for laser-plasma acceleration. We will show experimental measurements, numerical results and first applications in time-resolved spectroscopy.