  New acceleration technology is mandatory for the future elucidation of
fundamental particles and their interactions. A promising approach is to
exploit the properties of plasmas. Past research has focused on creating
large-amplitude plasma waves by injecting an intense laser pulse or an electron
bunch into the plasma. However, the maximum energy gain of electrons
accelerated in a single plasma stage is limited by the energy of the driver.
Proton bunches are the most promising drivers of wakefields to accelerate
electrons to the TeV energy scale in a single stage. An experimental program at
CERN -- the AWAKE experiment -- has been launched to study in detail the
important physical processes and to demonstrate the power of proton-driven
plasma wakefield acceleration. Here we review the physical principles and some
experimental considerations for a future proton-driven plasma wakefield
accelerator.
