Abstract:
In this colloquium, we provide an overview of the Plasma Wakefield Accelerator (PWFA) driven by relativistic charged particle beams. Together with the laser-driven Laser Wakefield Accelerator (LWFA), these two schemes are complementary and have become the two major plasma-based accelerator concepts actively pursued worldwide, evidenced by several recent whitepapers published by major international consortiums that chart the R&D roadmap in the next 20 years toward a full-scale plasma-based high energy collider. Several fundamental aspects in beam dynamics of plasma wakefield accelerators will be reviewed, which include the issues of beam loading, phase slippage, transformer ratio, and the universal beam self-induced plasma focusing effect. Considering the pros and cons between LWFA and PWFA, a Hybrid LWFA+ PWFA concept was introduced with the attempt to take advantage of each scheme, which may become the future direction. In addition to the application to high energy physics and free electron lasers, plasma wakefield principle has also been applied to address the challenging issues in other frontier fields of physics, such as astrophysics, cosmology, and gravity. In particular, it was proposed that plasma wakefields are responsible for the production of the observed ultra-high energy cosmic rays beyond 1020 eV. Another exciting application is to create laser-induced flying plasma mirrors as analog black holes in the laboratory to investigate the celebrated Hawking radiation and its associated black hole information loss paradox.