Systematic investigations and improvements of the efficiency, purity and emittance of charge bred ion beams from an ECRIS charge state booster by plasma stabilization using two frequency heating.

通过使用两种频率加热进行等离子体稳定，对来自 ECRIS 电荷态增强器的电荷孕育离子束的效率、纯度和发射率进行系统研究和改进。

• 批准号: SAPPJ-2019-00046
• 负责人: Kester, Oliver
• 金额: $ 2.91万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718946
• 关键词: Systematic; investigations; improvements; efficiency; purity

The TRIUMF charge state booster (CSB), based on a 14.5 GHz PHOENIX ECR ion source, raises the charge state of ions from rare isotopes prior to injection into the post accelerator linac. Therewith it allows TRIUMF the post acceleration of isotopes from elements beyond mass 30 to the medium mass range and avoids the stripping of ions at very low kinetic energies, which is not efficient in terms of transmission. An inherent issue of the CSB is that an ECR Ion Source does not operate at Ultra High Vacuum (UHV) conditions and has a significant output of background ions. That's the reason why the level of impurities in such devices is generally high which is a drawback when dealing with very low radioactive ion intensity injection. Investigations of the 1+ to n+ conversion processes in the community demonstrated that the efficiency of the process and quality of the highly charged ion beam produced by the CSB can be significantly enhanced by optimizing the plasma conditions and the beam formation in the extraction region. The ECRIS is superior to an EBIS related to the production of intense beams of rare isotopes >10^8 per second, which is required for nuclear astrophysics experiments. However, the 1+to n+ conversion rate depends on the flexibility of the injection optics, the plasma conditions and the beam formation upon ion extraction, which need to be improved and are the objective of leading edge research in this area. The main objective of this proposal is to improve the TRIUMF CSB performance in terms of beam quality, charge breeding efficiency and beam purity, by introducing techniques which are matter of investigations in the community. The goal is to bring TRIUMF back into the international leadership in charge breeding with ECRIS devices and to deliver higher quality and new beams to the experiments at ISAC. As the injection- and the ionisation efficiency as well as the beam purity essentially depend on the plasma conditions, the two-frequency heating and the tuning of the microwave frequency, will be introduced. These techniques rely on the generation of plasma modes that allow higher plasma densities and optimum coupling of the rf-power as well as stable plasma conditions. The project described in this proposal intends to investigate systematically the charge breeding efficiency and the beam quality by - modifying the plasma conditions using two frequency heating and frequency tuning - beam emittance measurements and corresponding beam extraction calculations. In addition, the CSB will be used to generate intense beams from offline samples for the first time. The significant improvement of the CSB breeding efficiency, the beam properties and additional beam production capabilities will benefit the experimental program at ISAC in particular for accelerated beam experiments. The second aspect is the training of highly qualified personnel in the field of plasma ion sources in general and on ECRIS sources.

TRIUMF 电荷状态增强器 (CSB) 基于 14.5 GHz PHOENIX ECR 离子源，可在注入后加速器直线加速器之前提高稀有同位素离子的电荷状态。因此，它允许 TRIUMF 将同位素从质量超过 30 的元素后加速到中等质量范围，并避免离子在非常低的动能下剥离，这在传输方面效率不高。 CSB 的一个固有问题是 ECR 离子源无法在超高真空 (UHV) 条件下运行，并且会产生大量背景离子。这就是为什么此类设备中的杂质含量通常较高的原因，这在处理非常低的放射性离子强度注入时是一个缺点。对社区中 1+ 到 n+ 转换过程的研究表明，通过优化提取区域中的等离子体条件和束流形成，可以显着提高 CSB 产生的高电荷离子束的过程效率和质量。 ECRIS 优于 EBIS，涉及每秒产生 >10^8 的稀有同位素强束，这是核天体物理实验所需的。然而，1+到n+的转化率取决于注入光学器件的灵活性、等离子体条件和离子提取时的束形成，这些都需要改进，并且是该领域前沿研究的目标。 该提案的主要目标是通过引入社区研究的技术来提高 TRIUMF CSB 在光束质量、电荷繁殖效率和光束纯度方面的性能。目标是通过 ECRIS 设备使 TRIUMF 重新成为负责育种的国际领导者，并为 ISAC 的实验提供更高质量的新光束。由于注入效率和电离效率以及束纯度基本上取决于等离子体条件，因此将引入双频加热和微波频率调谐。这些技术依赖于等离子体模式的生成，从而实现更高的等离子体密度、射频功率的最佳耦合以及稳定的等离子体条件。本提案中描述的项目旨在通过以下方式系统地研究电荷育种效率和光束质量： - 使用两个频率加热和频率调谐来修改等离子体条件 - 光束发射率测量和相应的光束提取计算。 此外，CSB将首次用于从离线样品中产生强光束。 CSB 育种效率、光束特性和附加光束生产能力的显着提高将有利于 ISAC 的实验计划，特别是加速光束实验。第二个方面是对一般等离子体离子源和 ECRIS 源领域的高素质人员进行培训。