| Paper | Title | Page |
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MOAA01 |
Design of the Superconducting Linac for CiADS Facing High Reliability | |
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Funding: Supported by NSF U22A20261, Large Research Infrastructures - China initiative Accelerator Driven System CiADS is the world’s first Accelerator Driven System with a Mega-watt beam power. The linac of CiADS consists of a 500 MeV and 5 mA with five-family superconducting resonators located directly downstream of the Radio Frequency Quadrupole (RFQ). The most significant challenge in designing the superconducting linac for CiADS is to ensure high-reliability operation with minimal beam loss control at 10-7 level and availability maximization through specifically designed hardware and software. In this presentation, we will discuss the physical design of the superconducting linac, including the fault compensation based on beam loss control and high reliability designs of the RF amplifier and power supply. |
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TUPB001 |
Research on Electromagnetic Structure and Transverse Dynamics of RFQ accelerator over 700MHz | |
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| The purpose of this research is to explore the dynamic and RF characteristics of RFQ with working frequency greater than 700 MHz, and to form a reliable RFQ physical design that meets the requirements of S-band linear accelerator injector. When the working frequency is increased to more than 700 MHz, the volume of RFQ will be reduced, but there will be many physical problems. The characteristics from 700MHz to 1.5GHz RFQ were studied on the beam dynamics. Based on the results of small acceptance RFQ commissioning, the design of the radial section and the control of beam loss were completed, and the RFQ design with a frequency of 750MHz was obtained with the energy of 2MeV, a length of 92.77cm, and an acceleration gradient of 2.15MV/m. The transmission efficiency is 94.4%. The RF characteristics from 700MHz to 1.5GHz RFQ were studied, and the RF design with a frequency of 750MHz was obtained, the power loss was 200W/mm, the Q₀ value was 7540, the flatness of the electric field was within ±2%, and the largest field asymmetry was 6.7%. We have designed, constructed, and cold-test the 750MHz cavity, the measured results are in agreement with simulated one. | ||
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TUPB002 |
100mA superconducting linac dynamic design | |
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| Beam loss is a critical challenge in the physics design of high power superconducting proton linacs. The challenge is even more acute in linacs that feature high peak intensity and low energy, which has strong space charge effect and RF nonlinear force. In this paper, we study how to achieve a high transmission rate for beam halo particles, commonly a major source of beam loss, via beam halo matching and acceptance optimization. We employ this method of beam loss reduction to improve the physics design of a high power 100mA superconducting linac which has potential applications in high brightness neutron production. | ||
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TUPB007 |
The Mebt Design for Ads With Dual Injectors | |
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| Due to the failure compensating nature of superconducting cavities, using online backup at the room temperature front end in ADS is an effective physical solution to improve beam availability. This 2.1MeV, 10mA partial transformation MEBT plays an important role in transporting and matching the beam from the outlet of the two injectors to the entrance of the superconducting cavity while it requires appropriate design to minimize the effects of both dispersion and space charge effects on horizontal and longitudinal focusing. This paper presents the design of the MEBT for the ADS project, including the selection of elements and the study of beam dynamics. Additionally, we will demonstrate the multi-particle tracking results using TraceWin. | ||
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| TUPB012 | Control of CAFe Beam Energy Using Linear Accelerator Simulation Software AVAS and Beam Line Calibration Technology | 105 |
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| A new accelerator simulation code named Advanced Virtual Accelerator Software (AVAS) was developed by the Institute of Modern Physics, Chinese Academy of Science. Although the code is proposed to simulate the particle transport in the linac of the China Initiative Accelerator Driven System (CiADS), it can be also used for common linacs. We have constructed a framework for the accelerator simulation program AVAS based on the structure, function, parameters, errors, and operational logic of real accelerators. The mapping relationship between the operating parame-ters and simulation parameters of the Chinese ADS Front-end Demo Linac (CAFe) superconducting sec-tion was successfully established through AVAS. In the testing experiment, AVAS successfully set the operat-ing parameters of the CAFe superconducting section, and the deviation between the energy setting value and the actual measurement value was about 0.5%. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-SAP2023-TUPB012 | |
| About • | Received ※ 30 June 2023 — Revised ※ 09 July 2023 — Accepted ※ 11 July 2023 — Issued ※ 24 March 2024 | |
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TUPB022 |
Observation of Pilot H⁻ Beam in high power proton linac | |
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| Chinese ADS Front End (CAFe) is a demo high-power proton superconducting linac for ADS project. During high-power beam commissioning of CAFe, unexpected irradiation dose was observed at the vacuum valve at the exit of the dipole magnet opposite to the proton beam deflection direction. The reason of the irradiation cannot be explained by neutron induced reaction or the operation history of the dipole magnet. A gamma-ray analysis of radionuclides is performed with the wipe sample from the valve, excluding the possibility of the neutron induced activation and verifying the proton induced reaction. Thus, it is supposed that H¿ beam is generated at the low energy transport section and accelerated simultaneously with proton beam in the superconducting linac. In this paper, The accelerating efficiency of pilot H⁻ beam is studied with multi-particle simulation software, Tracewin. The yield of H⁻ beam is obtained by cross section calculation of proton beam with residual gas at low energy transport section. The accumulated dose at the vacuum valve is calculated by FLUKA code and compared to the simulation result. | ||
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TUPB036 |
Optimisation of RFQ Transmission Efficiency Based on Reinforcement Learning Control Policy | |
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| The reinforcement learning (RL) algorithm is utilized to control the low-energy beam transport (LEBT) and radiofrequency quadrupole (RFQ) in linear accelerators, with the aim of improving RFQ transmission efficiency, achieving high beam intensity, reducing debugging time, and improving operational efficiency. A neural network model is established as part of the Interaction environment to partially replace the Tracewin software for RL training proceess. The SAC algorithm is a reinforcement learning algorithm used to optimize control policies for continuous action spaces. By using the SAC algorithm and interacting with the neural network model, a policy was trained to control the LEBT solenoids, optimizing the RFQ transmission efficiency to above 95% on the simulation software Tracewin. To test the generalization ability of the strategy, we applied it to a real accelerator and successfully validated its ability to optimize the RFQ transmission efficiency. The results demonstrate that RL policy trained in simulation-based environments can be applied on real accelerator control. | ||
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