Evolution of Transversely Asymmetric Electron Beams in Hollow Plasma Channels
Abstract
Plasma wakefield acceleration in hollow plasma channels has emerged as a promising approach for positron acceleration, since an electron beam can drive wakes with a transversely uniform accelerating field and no intrinsic defocusing force for positrons. Recently, it was proposed that a transversely asymmetric electron beam can excite quadrupole-dominated wakefield in a hollow channel, enabling the formation of accelerating and focusing fields suitable for positrons. However, the self-consistent evolution and stability of such asymmetric drivers, which are crucial for sustaining a usable wake over long distances, remain insufficiently understood. In this work, we investigate the evolution modes of wakefield driven by asymmetric electron beams in hollow plasma channels using fully three-dimensional particle-in-cell simulations. We identify two distinct unstable scenarios: a reversal of quadrupole field polarity and continuous penetration of the driver into the plasma wall. By analyzing the transverse dynamics of the driver and the restoring forces provided by the channel ions, we establish simple physical criteria that ensure stable propagation. These results clarify the fundamental constraints governing asymmetric-driver evolution, provide practical guidance for realizing long-lived, quasisteady wakes in hollow plasma channels, and indicate that the scheme can preserve mm·mrad-level normalized positron emittance.
Versions
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BibTeX
@misc{ding2026evolution,
title = {{Evolution of Transversely Asymmetric Electron Beams in Hollow Plasma Channels}},
author = {Siqin Ding and Jianfei Hua and Fei Li and Shiyu Zhou and Wei Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.24067},
eprint = {2606.24067},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.24067},
}
RIS
TY - UNPB
TI - Evolution of Transversely Asymmetric Electron Beams in Hollow Plasma Channels
AU - Siqin Ding
AU - Jianfei Hua
AU - Fei Li
AU - Shiyu Zhou
AU - Wei Lu
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2606.24067
UR - https://arxiv.org/abs/2606.24067
AB - Plasma wakefield acceleration in hollow plasma channels has emerged as a promising approach for positron acceleration, since an electron beam can drive wakes with a transversely uniform accelerating field and no intrinsic defocusing force for positrons. Recently, it was proposed that a transversely asymmetric electron beam can excite quadrupole-dominated wakefield in a hollow channel, enabling the formation of accelerating and focusing fields suitable for positrons. However, the self-consistent evolution and stability of such asymmetric drivers, which are crucial for sustaining a usable wake over long distances, remain insufficiently understood. In this work, we investigate the evolution modes of wakefield driven by asymmetric electron beams in hollow plasma channels using fully three-dimensional particle-in-cell simulations. We identify two distinct unstable scenarios: a reversal of quadrupole field polarity and continuous penetration of the driver into the plasma wall. By analyzing the transverse dynamics of the driver and the restoring forces provided by the channel ions, we establish simple physical criteria that ensure stable propagation. These results clarify the fundamental constraints governing asymmetric-driver evolution, provide practical guidance for realizing long-lived, quasisteady wakes in hollow plasma channels, and indicate that the scheme can preserve mm·mrad-level normalized positron emittance.
ER -