Mariner 10 radiation. The plasma experiment's goal was to study the ionized gases (plasma) of the solar wind, the temperature and density of its electrons, and how the planets affected the velocity of the plasma stream. The experiment contained two components, facing in opposite directions. The Scanning Electrostatic Analyzer was aimed toward the Sun, and could detect positive ions and electrons, which were separated by a set of three concentric hemispherical plates. The Scanning Electron Spectrometer was aimed away from the Sun, and detected only electrons, using just one hemispherical plate. The instruments could be rotated about 60 degrees to either side.
AWAKE bunch in the wakefield is thus crucial, since only a fraction (1/4th) of the wakefield is both focused and accelerated, which is needed for the trapping and the acceleration of the electrons. AWAKE is the first plasma wakefield experiment using a bunch of protons as a driver. Protons, as e.g. the protons form the CERN SPS, can carry a large amount of energy (~ 400 GeV). Therefore, they can produce wakefields in a plasma for much longer distances than a laser pulse or electron bunch as a driver due to energy depletion. A plasma can be seen as an ensemble