Large energy gain by a witness bunch in a single plasma wakefields stage requires a driver carrying a large amount of energy. Proton bunches produced in large synchrotrons (SPS or LHC at CERN) carry tens to hundreds of kilojoules, but are long, typically 6-12cm. The self-modulation (SM) of the bunch in the plasma  transforms the continuous bunch in a train of bunches shorter than, and separated by the wakefields period. The train then resonantly drives the wakefields to large amplitude (~GV/m). This is the scheme adopted by the AWAKE experiment  to accelerate electrons.
We will introduce the experiment, and present experimental results that show the occurrence of the SM process  its growth both along the bunch and along the plasma  its seeding with two methods, the robustness of the process against variations of the incoming bunch parameters and the observation, under some condition of the hosing instability. Results also show that these wakefields are suitable to accelerate electrons. Externally injected, ~19MeV electrons gained energy to ~2GeV .
We will briefly briefly outline plans and possible application of this acceleration scheme to high-energy physics.
- N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010)
- P. Muggli, AWAKE Collaboration, Plasma Physics and Controlled Fusion, 60(1) 014046 (2017)
- AWAKE Collaboration, Phys. Rev. Lett. 122, 054802 (2019)
- M. Turner, AWAKE Collaboration, Phys. Rev. Lett. 122, 054801 (2019)
- AWAKE Collaboration, Nature 561, 363 (2018)
|Working group||Invited plenary talk|