B. Alberdi-Esuain, J.-G. Hwang, T. Kamps
HZB, Berlin, Germany
HU Berlin, Berlin, Germany
Plasma-based accelerator technology is reaching a mature state, where applications of the beam for medical sciences, imaging, or as an injector for a future large-scale accelerator-driven light source become feasible. Particularly, the requirements for beam injection into a storage-ring-based light source are very strict with regards to beam quality and reliability. A non-invasive diagnostics greatly helps to reduce the commissioning time of the machine. We present a device suitable for online, non-destructive monitoring of the transverse spot size of the injected beam. In order to measure lateral beam sizes with a few-micrometer resolution, the technique uses an interferometric regime of coherent synchrotron radiation that is enabled by a sub-femtosecond short bunch-length. Simulations of the photon flux and the retrieval of the beam spot-size are performed for different bandwidth filters in order to define the bandwidth acceptance. Results show the potential of the proposed system that achieves precise retrieval of the complex degree of coherence at an extremely low photon intensity similar to those expected towards the plasma-acceleration injectors.
The demonstrations of GeV electron beams and FEL radiation driven by a centimeter-scale device illustrate the tremendous progress of laser-plasma accelerators. In such applications, beam divergence and size, along with beam energy and charge, are critical parameters of electron beams. An insight on the transverse parameters and their dynamics such as beam decoherence can be obtained by diagnostics complemented by betatron radiation detectors. This talk will also provide a brief overview of recent techniques for accessing the transverse phase space.