Title: Progress on Experiments towards LWFA-driven Transverse Gradient Undulator-Based FELs,
Abstract: Free Electron Lasers (FEL) are commonly regarded as the potential key
application of laser wakefield accelerators (LWFA). It has been found that
electron bunches exiting from state-of-the-art LWFAs exhibit a normalized
6-dimensional beam brightness comparable to those in conventional linear
accelerators. Effectively exploiting this beneficial beam property for
LWFA-based FELs is challenging due to the extreme initial conditions
particularly in terms of beam divergence and energy spread. Several different
approaches for capturing, reshaping and matching LWFA beams to suited
undulators, such as bunch decompression or transverse-gradient undulator
schemes, are currently being explored. In this article the transverse gradient
undulator concept will be discussed with a focus on recent experimental
achievements.