Dielectric laser accelerators
The QUASAR Group has recently launched studies into dielectric laser-driven accelerators (DLAs), which are strong potential candidates for ultra-compact electron accelerators and might even open up new avenues for future high energy physics accelerators and free-electron lasers. Due to a much higher damage threshold (0.2-2 J/cm2) than metals, these dielectric microstructures can support accelerating fields that are orders of magnitude higher than what can be achieved in conventional radio-frequency cavity-based accelerators. This can boost the acceleration gradients up to several GVs/m. Many candidates for DLAs have been proposed so far: Grating-based structures, photonic crystal structures and woodpile structures. A proof-of-principle experiment has successfully demonstrated acceleration of relativistic electrons with an accelerating gradient of 250 MeV/m in a fused silica double grating structure and the acceleration of non-relativistic 28 keV electrons through a single grating structure was also observed. These two experiments demonstrate the possibility of an all-optical DLA for full energy acceleration in the future.
Illustration of the first, second and third spatial harmonics for the case that one grating period is illuminated by laser from two sides.
Within this project we investigate into the acceleration of relativistic and non-relativistic electrons in double gratings silica structures. The optimization of these structures with regards to maximum acceleration efficiency for different spatial harmonics is ongoing. Simulations are performed with the commercial CST and VSim simulation codes and results from both codes are being compared. In a next step, considering the electrons bunch from VELA facility, electrons scattering and beam-loading simulation also will be done for comparison of experiments results. Finally, we are planning to carry out experimental studies into these structures using the available electron beam from VELA facility at Daresbury laboratory.
Currently involved QUASARs:
Y. Wei, C.P. Welsch, G. Xia, O. Mete, K. Hanahoe, J.D.A. Smith, ‘Investigations into dielectric laser-driven accelerators using the CST and VSIM simulation codes’, IPAC proceedings, Richmond, USA(2015) (WEPWA051)