Paper | Title | Other Keywords | Page |
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TUPOST025 | Beam Commissioning of the New Digital Low-Level RF System for CERN’s AD | LLRF, MMI, operation, proton | 911 |
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CERN’s Antiproton Decelerator (AD) has been re-furbished to provide reliable operation for the Extra Low ENergy Antiproton ring (ELENA). In particular, AD was equipped with a new digital Low-Level RF (LLRF) system that was successfully commissioned during the summer 2021. The new AD LLRF system has routinely captured and decelerated more than 3·107 antiprotons from 3.5 GeV/c to 100 MeV/c in successive steps, referred to as RF segments, interleaved by cooling periods. The LLRF system implements the frequency program from Btrain data received over optical fiber. Beam phase/radial and cavity amplitude/phase feedback loops are operated during each RF segment. An extraction synchronization loop is triggered on the extraction RF segment to transfer a single bunch of antiprotons to ELENA. Extensive diagnostics features are available and operational modes such as bunched beam cooling and bunch rotation have been successfully deployed. The LLRF parameters can be different for each RF segment and are controlled by a dedicated application. This paper gives an overview of the AD LLRF beam commissioning results obtained and challenges overcome. Hints on future steps are also provided. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST025 | ||
About • | Received ※ 25 May 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022 | ||
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TUPOST056 | Multi-Objective Bayesian Optimization at SLAC MeV-UED | electron, gun, controls, detector | 995 |
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SLAC MeV-UED, part of the LCLS user facility, is a powerful ’electron camera’ for the study of ultrafast molecular structural dynamics and the coupling of electronic and atomic motions in a variety of material and chemical systems. The growing demand of scientific applications calls for rapid switching between different beamline configurations for delivering electron beams meeting specific user run requirements, necessitating fast online tuning strategies to reduce set up time. Here, we utilize multi-objective Bayesian optimization(MOBO) for fast searching the parameter space efficiently in a serialized manner, and mapping out the Pareto Front which gives the trade-offs between key beam parameters, i.e., spot size, q-resolution, pulse length, pulse charge, etc. Algorithm, model deployment and first test results will be presented. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST056 | ||
About • | Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022 | ||
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TUPOPT036 | Two and Multiple Bunches with the LCLS Copper Linac | laser, controls, undulator, electron | 1089 |
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Two, four, and even eight bunches were accelerated through the copper linac. Two and four bunches were delivered successfully to photon experiments in both the hard (HXR) and soft (SXR) LCLS x-ray lines. In this paper we will concentrate on the more challenging issues, such as: the BPM deconvolution for both bunches, RF kicks at longer separations, tuning challenges, bridging the communications gap between the photon and electron side, the lower bunch charges for the eight bunch case, and rapid timing scans over several ns. We will describe some of the developed solutions and plans for the rest. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT036 | ||
About • | Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 28 June 2022 | ||
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TUPOPT064 | Online Optimization of NSLS-II Dynamic Aperture and Injection Transient | injection, kicker, sextupole, lattice | 1159 |
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The goal of the NSLS-II online optimization project is to improve the beam quality for the user experiments. To increase the beam lifetime and injection efficiency, we have developed a model-independent online optimization of nonlinear beam dynamics using advanced algorithms, such as Robust Conjugate-Gradient Algorithm (RCDS). The optimization objective is the injection efficiency and optimization variables are the sextupole magnet strengths. Using the online optimization technique, we increased the NSLS-II dynamic aperture and reduced the amplitude-dependent tune shift. Recently, the sextupole optimization was successfully applied to double the injection efficiency up to above 90% for the high-chromaticity lattice being developed to improve the beam stability and to in-crease the single-bunch beam intensity. Minimizing the beam perturbation during injection is the second objective in this project, realized by online optimization of the injection kickers. To optimize the full set of kicker parameters, including the trigger timing, amplitude, and pulse width, we upgraded all kicker power supplies with the capability of tunable waveform width. As a result, we have reduced the injection transient by a factor of 29, down to the limit of 60 um. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT064 | ||
About • | Received ※ 18 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 16 June 2022 | ||
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TUPOPT066 | KEK LUCX Facility Laser-to-RF&RF-to-RF Stability Study and Optimization | laser, feedback, LLRF, gun | 1167 |
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KEK LUCX facility* is a linear accelerator devoted to the beam instrumentation R&Ds for present and future accelerator systems and colliders including ILC. According to the ILC TDR**, it is necessary to achieve RF-gun Laser-to-RF&RF-to-RF phase stability of 0.35°(RMS) and amplitude stability of 0.07%(RMS) with implementation of the Digital LLRF feedback based on commercially available FPGA board and digital trigger system. As the first step to achieve ILC stability level at KEK-LUCX facility, present Laser-to-RF&RF-to-RF phase and amplitude jitters were measured using time- and frequency-domain techniques. After that, jitter influence on beam parameters after RF-gun and main solenoid magnet was simulated with ASTRA tracking code*** and results were cross-checked during LUCX facility beam operation. Finally, stable digital trigger system and digital LLRF feedback based on SINAP EVG&EVR and RedPitaya SIGNALlab-250 modules were implemented. This report demonstrates the results of Laser-to-RF&RF-to-RF phase and amplitude jitter measurements cross-checked with ASTRA simulation and real beam parameters measurements before and after LUCX facility stabilization.
References *A. Aryshev et al., Appl. Phys. Lett. 111, 033508 (2017). **International Linear Collider Reference Design Report, ILC-REPORT-2007-001, 2007. ***https://www.desy.de/~mpyflo/ |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT066 | ||
About • | Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022 | ||
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TUPOPT067 | Development of a Trigger Distribution System Based on MicroTCA.4 | electron, FPGA, controls, electronics | 1171 |
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We developed a MicroTCA.4 (MTCA.4) module to generate and distribute trigger timing signals. This module has 16 LVDS inputs and 16 LVDS outputs each on the front panel and the Zone 3 connector, and 8 M-LVDS I/O’s for MTCA.4 backplane. The trigger timing of each output can be precisely adjusted with the interval of 238 MHz or 509 MHz clocks by a 24-bit counter. The timing can also be fine-tuned by ~80 ps tap delay. This module has additional 5 optical transceivers, one for receiving trigger signals from upstream and four for fanouts to downstream. A master module distributes trigger signals, trigger counts, and event data through optical links. Slave modules generate trigger output signals with appropriate delays based on the event data and the local setting for each output channel. The timing jitter was measured to be 40 ps std, which is significantly smaller than the clock period of 238 MHz or 509 MHz. This system can also distribute an alarm signal received by a slave module to take data at a faulty situation. Trigger systems with this module have been utilized in SPring-8, SACLA, and NewSUBARU and stably synchronize various accelerator components with sufficient timing accuracy. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT067 | ||
About • | Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022 | ||
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THIYGD1 | White Rabbit Based Beam-Synchronous Timing Systems for SHINE | network, FEL, electron, FPGA | 2415 |
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Shanghai HIgh repetition rate XFEL aNd Extreme light facility (SHINE) is under construction. SHINE requires precise distribution and synchronization of the 1.003086 MHz timing signals over a long distance of about 3.1 km. Two prototype systems were developed, both containing three functions: beam-synchronous trigger signal distribution, random-event trigger signal distribution and data exchange between nodes. The frequency of the beam-synchronous trigger signal can be divided according to the accelerator operation mode. Each output pulse can be configured for different fill modes. A prototype system was designed based on a customized clock frequency point (64.197530 MHz). Another prototype system was designed based on the standard White Rabbit protocol. The DDS (Direct Digital Synthesis) and D flip-flops (DFFs) are adopted for RF signal transfer and pulse configuration. The details of the timing system design, laboratory test results will be reported in this paper. | |||
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Slides THIYGD1 [5.582 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THIYGD1 | ||
About • | Received ※ 29 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 17 June 2022 | ||
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THPOST013 | Development of a Detection System for Quasi-Monochromatic THz Pulse by a Spatially Modulated Electron Beam | electron, laser, radiation, cathode | 2469 |
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We have studied the generation of the broadband THz pulse using a compact linear accelerator. The THz pulse is generated by control of an electron beam angle to Cherenkov radiation angle. In addition, we have succeeded in producing a quasi-monochromatic THz pulse by the spatially modulated electron beam by passing through a slit. This work aims to develop a detection system to elucidate the spectrum of the quasi-monochromatic THz pulse. To detect it stably in a noisy radiation environment, the stability of probe laser system for Electro Optic sampling and timing synchronization system are important. In this conference, the generation method of each THz pulses, the results of development of detection system, and future prospect will be reported. | |||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST013 | ||
About • | Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 24 June 2022 | ||
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