Acceleration of electrons in the plasma wakefield of a proton bunch

2018
High-energy particle acceleratorshave been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. To increase the energy or to reduce the size of the accelerator, new accelerationschemes need to be developed. Plasma wakefield acceleration1–5, in which the electrons in a plasma are excited, leading to strong electric fields, is one such promising novel accelerationtechnique. Pioneering experiments have shown that an intense laser pulse6–9 or electron bunch10,11 traversing a plasma drives electric fields of tens of gigavolts per metreand above. These values are well beyond those achieved in conventional radio-frequency accelerators, which are limited to about 0.1 gigavolt per metre. A limitation of laser pulses and electron bunchesis their low stored energy, which motivates the use of multiple stages to reach very high energies5,12. The use of proton bunchesis compelling, as they have the potential to drive wakefields and accelerateelectrons to high energy in a single acceleratingstage13. The long proton bunchescurrently available can be used, as they undergo a process called self-modulation14–16, a particle–plasma interaction which longitudinally splits the bunchinto a series of high-density microbunches, which then act resonantly to create large wakefields. The Advanced Wakefield (AWAKE) experiment at CERN17–19 uses intense bunchesof protons, each of energy 400 gigaelectronvolts (GeV), with a total bunchenergy of 19 kilojoules, to drive a wakefield in a 10- metre-long plasma. Bunchesof electrons are injected into the wakefield formed by the proton microbunches. Here we present measurements of electrons acceleratedup to 2 GeV at the AWAKE experiment. This constitutes the first demonstration of proton-driven plasma wakefield acceleration. The potential for this scheme to produce very high-energy electron bunchesin a single acceleratingstage20 means that the results shown here are a significant step towards the development of future high-energy particle accelerators21,22.
    • Correction
    • Source
    • Cite
    • Save
    38
    References
    130
    Citations
    NaN
    KQI
    []
    Baidu
    map