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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - M-PAC (Miniature beam-driven Plasma ACcelerators)

Teaser

Particle accelerators, and the light sources they enable at wavelength down to below the ångström, are incredible tools for human discoveries, providing a unique window into the subatomic world and our understanding of Nature, allowing the study of the building blocks of...

Summary

Particle accelerators, and the light sources they enable at wavelength down to below the ångström, are incredible tools for human discoveries, providing a unique window into the subatomic world and our understanding of Nature, allowing the study of the building blocks of life at the molecular level, and opening countless societal applications, in medicine for therapy and diagnosis, in the semiconductor industry or in material processing and nondestructive inspection. Conventional accelerator technology has now reached its limit, and the idea of using an ionized gas –or plasma– as the medium sustaining the electric field used to accelerate particles, is very promising as accelerating fields few orders of magnitude higher are now possible. One class of plasma accelerators, that could become relevant to push the energy frontier of particle colliders, consists in using a particle beam, « the driver », to excite a plasma wave, that is then used to accelerate the main particle beam. Research in this area requires large facilities, and the project aims at powering these plasma accelerators with laser-accelerated electron beams, so as to miniaturize these beam-driven plasma accelerators. The first objectives of the project are: (i) to achieve a first proof-of-principle demonstration of a miniature beam-driven plasma accelerator, with a single electron beam and an optical visualization of the plasma accelerator structure, and (ii) to develop a dual beam configuration, where one bunch is the driver and the other one is the main beam to accelerate. This new plasma acceleration platform can then be used to address some of the key challenges in plasma accelerator research, such as energy efficiency or quality preservation. It can also be used to demonstrate the generation of bright electron beams and light sources with unprecedent brightness. The project also aims at addressing some of the challenges of plasma-based positron acceleration.

Work performed

Since the beginning of the project, a plasma accelerator powered by laser-accelerated electrons was successfully developed, and was probed with state-of-the-art optical visualization. Acceleration of a main beam in the miniature beam-driven plasma accelerator was also accomplished, as well as a first step towards the operation of these plasma accelerator with a dual beam configuration. The work performed also led to the discovery of new physics happening in the laser-solid interaction and probed by laser-accelerated electron beams at extremely short time scale. The potential of these plasma accelerators powered by laser-accelerated electron beams for the generation of bright gamma rays was demonstrated in a theoretical and numerical study, paving the way for its experimental demonstration. Significant progress in plasma-based positron acceleration was also achieved, showing how different regimes and plasma geometries can be used for the acceleration of a positron bunch, and their limitations.

Final results

It is expected that, until the end of the project, the generation of bright electron beams, beyond the state of the art, will be accomplished, using a variety of injection techniques. Similarly, the production of bright gamma rays, with unprecedented energy conversion efficiency from laser to gamma rays, is within experimental reach. Some of the critical milestones for the research field of plasma accelerators will be addressed, in particular high energy efficiency from the driver to the main beam, and the preservation of the quality of the beam during acceleration, in particular its emittance.