Advanced beam control and diagnostics for laser wakefield acceleratorsÂ
The last few decadeshas witnessed the prosperity of high intensity laser physics, thanks to theinvention of chirped pulse amplification (CPA) technique which was recognizedby a Nobel prize in physics in 2018. As one of the hot topics, laser wakefield accelerator(LWFA) is a very promising alternative to traditional radiofrequency (RF)particle accelerators due to its ultra-high accelerating gradients. With therapid development of laser technology, LWFA is now capable of generating electronbeams with multi-GeV energies. Such high-energy electron beams have been usedto drive novel secondary particle and radiation sources, including THz, XUV,X-ray, γ-ray, neutrons, positrons,etc. More importantly, they have been used to facilitate experimentalstrong-field quantum electrodynamics (QED) studies and to serve as a seed forcompact X-ray free electron lasers (XFELs). Another long-term goal of LWFA isto reach energies and beam quality suitable for future TeV electron-positroncolliders. However, these applications place highly restrictive requirements onthe beam quality in terms of maximum energy, energy spread, emittance, beamcharge, shot-to-shot stability and so on.  The electron beam quality critically relies onthe control of the injection process and subsequent beam dynamics. Therefore, deepunderstanding of the fundamental physics and detailed diagnosis of the electronbeam as well as the acceleration process in LWFA play critical roles incontrolling the beam qualities and eventually in facilitating practicalapplications. In this talk, I will first present our recent experimental workson fundamental physics and advanced diagnostics of LWFA. These includes revealing theself-injection in LWFA is polarization-dependent; Single-shot diagnosis ofelectron energy evolution via streaked betatron X-rays in a curved LWFA; Single-shotreconstruction of electron beam longitudinal phase-space in LWFA, etc. Then, I will envision the prospectson applying the curved LWFA into multi-stage LWFA towards the TeV lepton colliders;developing a platform for diagnosing electron phase space distribution with unprecedentedtemporal resolution to substantially advance diagnostics for the wholeaccelerator community.