Efficiency versus instability in plasma accelerators

Abstract

Plasma wakefield acceleration is one of the main technologies being developed for future high-energy colliders. Potentially, it can create a cost-effective path to the highest possible energies for e þ e − or γ − γ colliders and produce a profound effect on the developments for high-energy physics. Acceleration in a blowout regime, where all plasma electrons are swept away from the axis, is presently considered to be the primary choice for beam acceleration. In this paper, we derive a universal efficiency-instability relation, between the power efficiency and the key instability parameter of the trailing bunch for beam acceleration in the blowout regime. We also show that the suppression of instability in the trailing bunch can be achieved through Balakin-Novokhatsky-Smirnov damping by the introduction of a beam energy variation along the bunch. Unfortunately, in the high-efficiency regime, the required energy variation is quite high and is not presently compatible with collider-quality beams. We would like to stress that the development of the instability imposes a fundamental limitation on the acceleration efficiency, and it is unclear how it could be overcome for high-luminosity linear colliders. With minor modifications, the considered limitation on the power efficiency is applicable to other types of acceleration.

Plasma wakefield linear colliders—opportunities and challenges

“…BNS-damping was successfully applied to the Stanford Linear Collider [32] and will be used to stabilize the beam in the CLIC main linacs. BNS-damping will likely have similar effects for PWFA accelerators and has been proposed in [26,28]. The damping does not have to rely on correlated energy spread; any effect that produces a varied focus along the beam may have a stabilizing effect if the variation is tuned correctly.…”

“…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.…”

“…In a PWFA-LC, the drive beam defines the centre of the plasma channel, and thus cannot be offset with respect to this channel. However, inevitable transverse jitter between the drive beam and the main beam implies that the mainbeam intra-bunch wake may put significant constraints on the charge [28] [25,26], they may be grouped into three: reduction of instability seed [30]; disruption of the coherence and reduction of the beam-plasma coupling. Disruption of the coherence can be done in a variety of ways.…”

Mechanisms for the mitigation of the hose instability in plasma-wakefield accelerators

“…[14,22]), and hence, implies that the witness beam itself drives hosing. The associated challenge of stable acceleration in the high-efficiency (beam-loaded) regime of plasma-based accelerators was also addressed in [38].…”

Accelerator Physics Center at Fermilab : History and Accomplishments (2007-2018)

“…Seminal results were obtain in studies of Integrable non-linear optics (A.Valishev, et al), coherent beam stability (A.Burov, V.Balbekov, K.Y.Ng, et al), Landau damping with electron lenses and space-charge (V.Shiltsev, Yu.Alexahin, et al), beam phase-space manipulations (P.Piot, et al), beam-beam effects (Yu.Alexahin, T.Sen, A.Valishev et al), electron lenses for beam-beam and space-charge compensation and collimation (V.Shiltsev, G.Stancari, et al). See References [4,6,7,8,15,25,29,30,37,46,47,51,54,62,96,98,121,122,132,135,145,157,171,185,194,195] in Appendix E. II.11. Beam physics considerations for far-future colliders: carried out by several APC scientists and covered selected topics of efficient wakefield acceleration, technology and cost challenges of the colliders, channeling acceleration in crystals and carbon nanotubes, etc.…”