Speaker
Mariana Moreira
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.2020.pdf
Optimization of wakefield amplitude in the AWAKE experiment
M. Moreira1,3 , J. Vieira1 , P. Muggli2,3
1 Instituto Superior Técnico, Lisbon, Portugal
2 Max-Planck Institute for Physics, Munich, Germany
3 CERN, Geneva, Switzerland
AWAKE is a proton-driven plasma wakefield experiment [1] under way at CERN that in-
tends to prove one of the concepts for a plasma-based accelerator. The long length of the proton
bunches used in the experiment (∼6-12 cm) causes the bunch to undergo a self-modulation
process [2], through which the initial bunch is self-consistently transformed into a train of mi-
crobunches with lengths of the order of the plasma wavelength. This train can resonantly excite
a wakefield in the plasma, and the objective of the experiment is to ultimately accelerate an
externally injected electron bunch in this wakefield.
Though plasma-based accelerator concepts promise acceleration gradients a few orders of
magnitude larger than with conventional technology, in the case of AWAKE numerical simula-
tions indicate that the amplitude of the wakefield tends to drop significantly after saturation of
the self-modulation process, thus undermining the potential energy gain for injected electrons.
This work will investigate the causes of this decline using both particle-in-cell simulations and
linear wakefield theory. Two possible measures to sustain a high wakefield amplitude after satu-
ration are also studied: the use of an anti-proton driver, since electrons have been known to drive
wakefields more effectively than their positively-charged counterparts [3], and the introduction
of a plasma density step [4]. Simulation results will be presented.
References
[1] P. Muggli et al., Plasma Physics and Controlled Fusion, 60(1) 014046 (2017)
[2] N. Kumar, A. Pukhov and K. Lotov, Phys. Rev. Lett. 104, 255003 (2010)
[3] S. Lee, T. Katsouleas, R. G. Hemker, E. S. Dodd, and W. B. Mori, Phys. Rev. E 64, 045501 (2001)
[4] A. Caldwell, and K. V. Lotov, Phys. Plasmas 18, 103101 (2011)
