arXiv : Measurement of transverse wakefields induced by a misaligned positron bunch in a hollow channel plasma accelerator

Lindstrøm, C.A.; Gessner, S.J.; Frederico, J.; Beekman, C.; Marsh, K.A.; Doche, A.; Lu, W.; Clayton, C.E.; Allen, J.M.; Clarke, C.I.; O'Shea, B.D.; Joshi, C.; Green, S.Z.; Corde, S.; An, W.; Vafaei-Najafabadi, N.; Litos, M.; Yakimenko, V.; Adli, E.; Hogan, M.J.; Mori, W.B.

doi:10.1103/PhysRevLett.120.124802

Article
Report number	arXiv:1802.09000
Title	Measurement of transverse wakefields induced by a misaligned positron bunch in a hollow channel plasma accelerator
Author(s)	Lindstrøm, C.A. (Oslo U.) ; Adli, E. (Oslo U.) ; Allen, J.M. (SLAC) ; An, W. (UCLA, Los Angeles (main)) ; Beekman, C. (Palaiseau, Lab. Opt. Appl.) ; Clarke, C.I. (SLAC) ; Clayton, C.E. (UCLA, Los Angeles (main)) ; Corde, S. (Palaiseau, Lab. Opt. Appl.) ; Doche, A. (Palaiseau, Lab. Opt. Appl.) ; Frederico, J. (SLAC) ; Gessner, S.J. (SLAC) ; Green, S.Z. (SLAC) ; Hogan, M.J. (SLAC) ; Joshi, C. (UCLA, Los Angeles (main)) ; Litos, M. (Colorado U.) ; Lu, W. (Tsinghua U., Beijing) ; Marsh, K.A. (UCLA, Los Angeles (main)) ; Mori, W.B. (UCLA) ; O'Shea, B.D. (SLAC) ; Vafaei-Najafabadi, N. (UCLA, Los Angeles (main)) ; Yakimenko, V. (SLAC)
Publication	2018-03-27
Imprint	2018-02-25
Number of pages	5
Note	5 pages, 4 figures. Submitted to Physical Review Letters
In:	Phys. Rev. Lett. 120 (2018) 124802
DOI	10.1103/PhysRevLett.120.124802
Subject category	physics.acc-ph ; Accelerators and Storage Rings
Abstract	Hollow channel plasma wakefield acceleration is a proposed method to provide high acceleration gradients for electrons and positrons alike: a key to future lepton colliders. However, beams which are misaligned from the channel axis induce strong transverse wakefields, deflecting beams and reducing the collider luminosity. This undesirable consequence sets a tight constraint on the alignment accuracy of the beam propagating through the channel. Direct measurements of beam misalignment-induced transverse wakefields are therefore essential for designing mitigation strategies. We present the first quantitative measurements of transverse wakefields in a hollow plasma channel, induced by an off-axis 20 GeV positron bunch, and measured with another 20 GeV lower charge trailing positron probe bunch. The measurements are largely consistent with theory.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2018-2025 authors (License: CC-BY-4.0)

$PIC simulation using experimental parameters: a hollow channel with 215~$\mu$m inner and 280~$\mu$m outer radius at density $3\times10^{15}$~cm$^{-3}$, driven by a 0.41~nC drive bunch transversely offset by 20~$\mu$m and probed by a 0.1~nC probe bunch at a bunch separation of 600~$\mu$m. The high beam energy ensures that both the beam and the longitudinal (a) and transverse wakefields (b) stay approximately constant throughout the channel. The on-axis wakefields (red lines) are consistent with the model (black dashed lines) in the longitudinal, but diverges from the modeled transverse wakefield when electrons are pulled into the channel.$ $Correlation between probe bunch angular deflection and channel offset weighted by drive bunch charge from a random laser pointing and charge jitter, for the third step ($210\pm10$~$\mu$m) of the bunch separation scan. The linear trend line corresponds to a transverse wakefield $W_x/\Delta x =$~0.86~$\pm$~0.13~MV~pC$^{-1}$~m$^{-1}$~mm$^{-1}$, where the uncertainty is defined by the rms from the trend line increasing by 3\%. The error of each shot is negligible compared to the spread of the data points, caused by a combination of jitters in beam orbit, beam energy, bunch separation, plasma density and channel length.$ Show more plots

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记录创建於2019-02-09，最後更新在2022-08-10

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