jbchen

• Lopes, Nelson M.C.; Cobo, Claudia C.; Chen, Jian Bin Ben; Jurj, Paul Bogdan; Kennedy, Lewis C. & Vanstone, Alexander [Show all 7 contributors for this article] (2026). A metre-scale plasma discharge for plasma wakefield acceleration. Plasma Physics and Controlled Fusion. ISSN 0741-3335. 68(4). doi: 10.1088/1361-6587/ae5adc. Full text in Research Archive
• Adli, Erik; Lindstrøm, Carl A.; Kalvik, Daniel; Sjobak, Kyrre Ness; Finnerud, Ole Gunnar & Chen, Jian Bin Ben [Show all 7 contributors for this article] (2025). Transverse tolerances in the plasma-wakefield acceleration blow-out regime. Proceedings of the International Particle Accelerator Conference. ISSN 2673-5490. p. 1434–1437. doi: 10.18429/JACOW-IPAC2025-TUPS011. Full text in Research Archive Show summary

  We report on recent progress in transverse instabilities and transverse tolerances for plasma-wakefield accelerators in the blow-out regime. In this regime, the transverse fields provide both strong focusing and strong deflection via transverse wakefields. The deflection effect of the wakefields on the main beam leads to limitations on the acceleration efficiency, if not mitigated. Based on comprehensive particle-in-cell simulations we summarize recent findings of the instability--efficiency relation for the blow-out regime. Ion motion and energy spread may mitigate the instability; with linac start-to-end simulations, using the recently developed ABEL framework, we demonstrate that the instability and emittance growth may be sufficiently mitigated for the colliding beams in the HALHF concept. Independent of wakefield effects, the strong focusing fields lead to very tight tolerances for the drive-beam jitter. We quantify these tolerances, using examples from HALHF start-to-end simulations. We show that the tolerances are greatly loosened by applying external magnetic fields to guide the drive-beam propagation in the plasma.

• Adli, Erik; D’Auria, Gerardo; Catalan Lasheras, Nuria; Cilento, Vera; Corsini, Roberto & Doebert, Steffen [Show all 474 contributors for this article] (2025). CLIC readiness report. The European Physical Journal Special Topics (EPJ - Special Topics (EPJ ST)). ISSN 1951-6355. 234(22), p. 6473–6652. doi: 10.1140/epjs/s11734-025-02016-w. Full text in Research Archive
• Finnerud, Ole Gunnar; Lindstrøm, Carl Andreas; Chen, Jian Bin Ben & Adli, Erik (2025). The E302 instability-versus-efficiency experiment at FACET-II. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3124(1). doi: 10.1088/1742-6596/3124/1/012005. Full text in Research Archive Show summary

  We discuss plans for the E302 instability-efficiency experiment, starting in 2024 at the recently upgraded FACET-II facility at SLAC National Accelerator Laboratory. The beam-breakup instability will be the main area of study for the E302 experiment. With the imaging spectrometer at FACET-II, we introduce a novel technique for observing and quantifying the amplitude growth of the trailing bunch due to the transverse instability. Using the transverse position on the spectrometer screen and the transfer matrix of the magnetic lattice used for the spectrometer, we aim to extract a x′–E charge distribution that can be used to quantify the amplitude of the beam. By varying the trailing bunch’s charge and, hence, the beam loading of the accelerating field, we aim to adjust the wake-to-beam power transfer efficiency in the E302 experiment. We plan to quantify the amplitude for different configurations of the beam charge and, hence, investigate the relationship between the beam-breakup instability and efficiency. We use a combination of particle-in-cell (PIC) codes to simulate a beam-driven plasma wakefield accelerator from start-to-end with a FACET-II-like spectrometer and demonstrate the methodology that will be used for the instability studies at the E302 experiment.

• Chen, Jian Bin Ben; Lindstrøm, Carl Andreas; Finnerud, Ole Gunnar & Adli, Erik (2025). Modelling transverse instability in HALHF plasma stages. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 3124(1). doi: 10.1088/1742-6596/3124/1/012015. Full text in Research Archive Show summary

  We present first results for a parameter study of the plasma linac of HALHF, a novel electron-positron collider concept combining plasma wakefield acceleration and mature RF acceleration to reach a centre of mass energy of 250 GeV. This study is a preliminary extension of the previous studies that indicated promising performance, by including transverse instability. Transverse instability was simulated using start-to-end simulations, where PIC simulations were combined with a simplified model to efficiently model transverse instability in the plasma-acceleration stages. No interstage optics were included. With a small initial transverse offset, the currently proposed parameter set will result in emittance growth and charge losses. If additional transverse misalignments are introduced between stages in the form of drive beam transverse jitter, the emittance growth is even more severe. Mitigation mechanisms to reduce the instability to an acceptable level are suggested.

• Foster, Brian; Adli, Erik; Barklow, Timothy L.; Berggren, Mikael; Boogert, Stewart & Chen, Jian Bin Ben [Show all 24 contributors for this article] (2025). Proceedings of the Erice workshop: A new baseline for the hybrid, asymmetric, linear Higgs factory HALHF. Physics Open. 23. doi: 10.1016/j.physo.2025.100261. Full text in Research Archive Show summary

  The HALHF collaboration has discussed a new baseline for the project, taking into account comments from the accelerator community on various aspects of the original design. In particular, these concerned the practicality of the dual-purpose linac to accelerate both colliding positron bunches and the drive beams required for the plasma linac. In addition, many other aspects of the project were also considered; the discussion and conclusions are documented in this paper. Finally, a new baseline is outlined that has been optimised and addresses several weaknesses in the original design, has higher luminosity, reduced centre-of-mass energy boost and additional features such as two interaction points and positron polarisation as well as electron polarisation. Although HALHF has become longer and more expensive, it remains significantly smaller and cheaper than other mature Higgs factory designs currently under discussion.

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• Chen, Jian Bin Ben; Adli, Erik; Drobniak, Pierre; Finnerud, Ole Gunnar; Hørlyk, Eir Eline & Kalvik, Daniel [Show all 9 contributors for this article] (2025). ABEL: The adaptable beginning-to-end linac simulation framework. doi: 10.18429/JACOW-IPAC2025-TUPS012. Full text in Research Archive Show summary

  We introduce ABEL, the Adaptable Beginning-to-End Linac simulation framework developed for agile design studies of plasma-based accelerators and colliders. ABEL’s modular architecture allows users to simulate particle acceleration across various beamline components. The framework supports specialised codes such as HiPACE++, Wake-T, ELEGANT, GUINEA-PIG and CLICopti, which facilitate precise modelling of complex machine components. Key features include simplified models for addressing transverse instabilities, radiation reactions, and ion motion, alongside comprehensive diagnostics and optimisation capabilities. Our simulation studies focus on the HALHF plasma linac, examining tolerances for drive beam jitter, including effects of self-correction mechanisms. Simulation results demonstrate ABEL's ability to model emittance growth under transverse instability and ion motion, highlighting the framework’s adaptability in balancing simulation fidelity with computational efficiency. The findings point towards ABEL’s potential for advancing compact accelerator designs and contribute to the broader goals of enhancing control and precision in plasma-based acceleration.

• Lindstrøm, Carl A.; Adli, Erik; Chen, Jian Bin Ben; Drobniak, Pierre; Hørlyk, Eir Eline & Kalvik, Daniel [Show all 28 contributors for this article] (2025). Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory. doi: 10.18429/JACOW-IPAC2025-MOCD1. Full text in Research Archive Show summary

  Particle physicists aim to construct a electron–positron Higgs factory as the next major particle collider. However, the high associated costs motivate the development of more affordable collider designs. Plasma-wakefield acceleration is a promising technology to this end. HALHF is a proposal for a Higgs factory that utilizes beam-driven plasma-wakefield acceleration to accelerate electrons to high energy with high gradient, while using radio-frequency acceleration to accelerate positrons to a lower energy. This asymmetry sidesteps a major difficulty in plasma acceleration: that of accelerating positrons with high efficiency and quality. Since publication, several challenges were identified in the original baseline design. We summarize the updated baseline design, which addresses these challenges, and describe the parameter- and cost-optimization process used to arrive at this design.

• Chen, Jian Bin Ben (2020). Instability and Beam-Beam Study for Multi-TeV PWFA e+e- and yy Linear Colliders. Universitetet i Oslo. Full text in Research Archive

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