Physics and Experiments for AWAKE Run 2

The AWAKE experiment at CERN is at the beginning of its Run 2. It will focus on seeding of the self-modulation process with a short electron bunch rather than with a relativistic ionization front (Run 1), and on maximizing the amplitude of wakefields along the plasma using a density step [A. Caldwell et al., Phys. Plasmas 18, 103101 (2011)]. For seeding we will use the 20MeV electron bunch of the Run 1 acceleration experiments.  Phase reproducibility measurements will be similar to those of  [F. Batsch et al., Phys. Rev. Lett. 126, 164802 (2021)]. The density step will be imposed through a temperature step along the laser-ionized rubidium vapor source. We will observe the effects of the density step on the beam halo, on the self-modulation, on electron acceleration and on plasma light emission. Acceleration of an externally-injected electron bunch with a plasma for self-modulation, including density step and electron bunch seeding followed by a plasma for acceleration will focus on bunch quality at the multi-GeV energy level. We are also investigate discharge and helicon plasma sources for acceleration over very long distances. We will present the global physics and experimental plan.