Plasma-based accelerators driven by particle beams

As we push the frontier of particle physics to higher particle energies, conventional accelerator techniques are attaining their limits. The use of an ionized gas —or plasma— circumvents the most significant barrier of conventional techniques by increasing the energy gained per unit length by several orders of magnitude. One class of plasma accelerators, relevant for high energy physics and light source applications, consists in using a particle beam, « the driver », to excite a plasma wave, that can then accelerate the main particle beam. These beam-driven plasma accelerators have made considerable progress in the past few years, with groundbreaking results such as the high-efficiency acceleration of an electron beam [1], the multi-gigaelectronvolt acceleration of positrons [2], and proton-driven electron acceleration [3].

Here we report on progress made in plasma-based accelerators using particle beam drivers from conventional RF accelerators as well as from novel laser-driven accelerators. First, we will present results on the successful acceleration of positron beams in plasma-based accelerators, and discuss intrinsic limitations, from experimental measurements and from theory and simulations. Second, we will show the first proof-of-principle demonstration of a plasma-based accelerator powered by laser-accelerated electron beams, and will discuss new possibilities opened by these results, from the direct optical imaging of the accelerating structure to the generation of bright beams beyond the state of the art.

Finally, we will discuss the perspectives of the field and the key physics challenges for plasma accelerators that need to be tackled in the future.

[1] Nature 515, 92 (2014).
[2] Nature 524, 442 (2015).
[3] Nature 561, 363 (2018).