Short-range wakefields generated in the blowout regime of plasma-wakefield acceleration

Abstract

In the past, calculation of wakefields generated by an electron bunch propagating in a plasma has been carried out in linear approximation, where the plasma perturbation can be assumed small and plasma equations of motion linearized. This approximation breaks down in the blowout regime where a high-density electron driver expels plasma electrons from its path and creates a cavity void of electrons in its wake. In this paper, we develop a technique that allows to calculate short-range longitudinal and transverse wakes generated by a witness bunch being accelerated inside the cavity. Our results can be used for studies of the beam loading and the hosing instability of the witness bunch in PWFA and LWFA.

On "Efficiency versus Instability in plasma accelerators"

“…This fact for structures and hollow plasma channels explicitly follows from the Relativistic Gauss theorem [2] and for the case of the plasma bubble from the analysis of the Ref. [4].…”

“…While in general, this expression is indeed not correct, as was shown Ref. [4], under certain assumptions it still holds, but what is more important that it always holds if the = sign is replaced with the ≤ sign. This fact for structures and hollow plasma channels explicitly follows from the Relativistic Gauss theorem [2] and for the case of the plasma bubble from the analysis of the Ref.…”

“…[8] based on Ref. [4] that this expression might not be applicable in a plasma bubble. While in general, this expression is indeed not correct, as was shown Ref.…”

“…For the case of the plasma bubble, recently in Ref. [4] G. Stupakov showed that expressions for the short-range wakefields in the plasma cavity used in the paper are the upper bounds of the real wake potentials.…”

Plasma wakefield linear colliders—opportunities and challenges

“…While no attempt at quantifying transverse tolerances is made in [19], theoretical descriptions of the transverse hosing instability in PWFA exist [24][25][26], and simplified models of the transverse instabilities have recently been suggested [27][28][29]. The simplified models aim at modelling the PWFA-instability in the same language used for describing the well-known BBU instability in RF accelerators; the transverse forces are expressed as a wake function, parametrized only as a function of the plasma cavity size.…”