Periodic Reporting for period 4 - M-PAC (Miniature beam-driven Plasma ACcelerators)
Periodo di rendicontazione: 2021-07-01 al 2021-12-31
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 project achieved 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 then developed 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 together with the development of novel methodologies were then used to address some of the key challenges in plasma accelerator research, such as energy efficiency or quality preservation. The project also showed the potential for the generation of bright electron beams and light sources with unprecedented brightness, and pushed our capabilities and understanding of plasma-based positron acceleration.
During 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 the operation of these plasma accelerators 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 electron beams and radiation sources was demonstrated theoretically and experimentally. 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.
The demonstration of hybrid staging of laser-driven and beam-driven plasma accelerators has marked a major milestone with the birth of a new avenue of research with very strong potential. The original concepts proposed for gamma-ray sources have provided unique opportunities, as well as a new approach for the study of strong-field quantum electrodynamics.
The findings of the project on relativistic streaming plasma instabilities occurring in laser-solid or beam-plasma interaction have opened a new approach to laboratory astrophysics by probing microinstabilities using femtosecond laser or particle beams.
A distinct positron bunch was successfully accelerated for the first time in a plasma, and a new picture of positron acceleration in plasmas was proposed theoretically, highlighting how energy efficiency and beam quality need to be looked at simultaneously and how the existing trade-off between these quantities is fundamentally different from the case of electron acceleration.
The findings of the project on relativistic streaming plasma instabilities occurring in laser-solid or beam-plasma interaction have opened a new approach to laboratory astrophysics by probing microinstabilities using femtosecond laser or particle beams.
A distinct positron bunch was successfully accelerated for the first time in a plasma, and a new picture of positron acceleration in plasmas was proposed theoretically, highlighting how energy efficiency and beam quality need to be looked at simultaneously and how the existing trade-off between these quantities is fundamentally different from the case of electron acceleration.