| Paper | Title | Page |
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| MOPAB241 | Design of the Proton and Electron Transfer Lines for AWAKE Run 2c | 778 |
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| The AWAKE Run 1 experiment achieved electron acceleration to 2 GeV using plasma wakefield acceleration driven by 400 GeV, self-modulated proton bunches from the CERN SPS. The Run 2c phase of the experiment aims to build on these results by demonstrating acceleration to ~10 GeV while preserving the quality of the accelerated electron beam. To realize this, there will be an additional plasma cell, to separate the proton bunch self-modulation and the electron acceleration. A new 150 MeV beamline is required to transport and focus the witness electron beam to a beam size of several microns at the injection point. This specification is designed to preserve the beam emittance during acceleration, also requiring micron-level stability between the driver and witness beams. To facilitate these changes, the Run 1 proton transfer line will be reconfigured to shift the first plasma cell 40 m downstream. The Run 1 electron beamline will be adapted and used to inject electron bunches into the first plasma cell to seed the proton bunch self-modulation. Proposed adjustments to the proton transfer line and studies for the designs of the two electron transfer lines are detailed in this contribution. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB241 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021 | |
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| MOPAB173 | Physics Program and Experimental for AWAKE Run 2 | 586 |
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Run 1 experimental results demonstrate many characteristics of the self-modulation (SM) in plasma of a long, 400GeV SPS proton bunch*. Externally injected, 19MeV electrons were accelerated to 2GeV**. Based on these results, we are assembling a physics and experiment program aiming at producing a multi-GeV electron bunch with emittance and energy spread sufficiently low for possible early applications to high-energy physics experiments. Plans include two plasmas, the first for SM, the second for acceleration, and of scalable length, separated by an injection region. The first plasma includes a density step to maintain large-amplitude wakefields after saturation of the SM process. Seeding of the SM process may be obtained from an electron bunch. The 150MeV witness electron bunch from an S-band gun, X-band linac has parameters that produce plasma electron blow out and loading of the wakefields in order to minimize final energy spread and emittance***. We are studying the possibility of using a helicon plasma source for the accelerator, a source that can in principle be very long (100s of m).
*AWAKE, PRL 122, 054802 (2019), Turner, PRL 122, 054801 (2019), Turner, PRAB 23, 081302, (2020), Braunmueller PRL 125, 264801 (2020) **AWAKE, Nature 561, 363 (2018) ***Olsen, PRAB 21, 011301 (2018) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB173 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 02 September 2021 | |
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| TUPAB160 | Preparation for Electron-Seeding of Proton Bunch Self-Modulation in AWAKE | 1761 |
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| The next milestone of the Advanced Wakefield Experiment (AWAKE) at CERN will be to demonstrate that the self-modulation of a long proton bunch can be seeded by a short electron bunch preceding it. This seeding method will lead to phase-reproducible self-modulation of the entire proton bunch, as required for the future AWAKE program. In the Spring of 2021, before receiving proton beams from the CERN SPS, AWAKE plans to hold a dry run of the electron seeding experiments, to commission the system and to determine the parameter scans that will be used in experiments with protons. Electron bunches of 10-20 MeV with varying charge, radius, emittance and energy will be sent in 10 m of low-density plasma. The effects of beam-plasma interactions on the amplitude of the wakefields driven by the different bunches will be studied by observing the energy spectra at the end of the plasma. This paper presents preliminary experimental results from the first two days of measurements as well as the beginning of a simulation-based study of electron propagation in plasma. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB160 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 27 August 2021 | |
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| TUPAB138 | Determination of the Phase of Wakefield Driven by a Self-Modulated Proton Bunch in Plasma | 1710 |
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Funding: This work was partly supported by the National Research Foundation of Korea (Nos. NRF-2016R1A5A1013277 and NRF-2020R1A2C1010835) The phase of wakefield driven by a self-modulated proton bunch depends on the type of seeding method and by the beam-plasma parameters.* Particularly when a preceding electron bunch generates seed wakefield, the proton bunch modulation is strongly affected by the seed bunch dynamics along with the plasma. Intrinsic wakefield dephasing from self-modulation of proton bunch can lead to complex evolution of the bunch and wakefield, making it difficult to design an experimental setup for witness beam injection. Using the particle-in-cell code FBPIC,** we investigate in detail the trends of seed electron and driver proton bunch parameter sensitivity to the phase of wakefield in time in the proton bunch frame. We focus on the parameters affecting the phase of the wakefield through the beam’s radial dynamics, such as beam emittance, radial size, energy, and beam to plasma density ratio. Parameter variations are compared to those in the case of the phase of wakefield driven by a non-evolving seed bunch. *F. Batsch, arXiv:2012.09676 [physics.plasm-ph] **R. Lehe, M. Kirchen, I.A. Andriyash, B.B. Godfrey, and J.-L. Vay, Comput. Phys. Comm. 203, 66-82 (2016) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB138 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021 | |
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| TUPAB158 | Electron Witness Constraints for AWAKE | 1753 |
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The AWAKE project at CERN successfully demonstrated the use of a proton driver to accelerate an electron witness in plasma*. One of the key goals for AWAKE Run2 is to better control this acceleration, separating the proton-beam-modulation and electron-acceleration stages in order to achieve high energy electrons with high beam quality. Controlled acceleration additionally requires careful tuning of the witness bunch parameters at the injection point. In this work, we use particle-in-cell simulations to study the tolerances for this matching, and discuss techniques to loosen these constraints.
*Adli et al. (AWAKE Collaboration), Nature (2018) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB158 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 11 August 2021 | |
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