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.

TRIUMF电荷态加速器(CSB)基于14.5 GHz的菲尼克斯ECR离子源，在注入后加速器直线加速器之前，从稀有同位素中提高离子的电荷态。因此，它允许TRIUMF将同位素从质量超过30的元素加速到中等质量范围，并避免了在极低动能下离子的剥离，这在传输方面是无效的。CSB的一个固有问题是ECR离子源不能在超高真空(UHV)条件下运行，并且有大量的本底离子输出。这就是为什么这类设备中的杂质水平通常很高的原因，这在处理极低放射性离子强度注入时是一个缺点。对社区中1到n转换过程的调查表明，通过优化等离子体条件和引出区域中的束流形成，可以显著提高CSB产生的高电荷离子束的过程效率和质量。ECRIS优于与产生每秒10^8个稀有同位素的强流束有关的EBIS，后者是核天体物理实验所必需的。然而，1到n的转换率取决于注入光学的灵活性、等离子体条件和离子引出时的束流形成，这些都需要改进，是该领域前沿研究的目标。这项建议的主要目的是通过引入社会上正在研究的技术，在束流质量、电荷繁殖效率和束流纯度方面改善TRIUMF CSB的性能。目标是让TRIUMF重新成为负责ECRIS设备育种的国际领先企业，并为ISAC的实验提供更高质量的新光束。由于注入和电离效率以及束流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的调谐。这些技术依赖于等离子体模式的产生，这种模式允许更高的等离子体密度和最佳的射频功率耦合以及稳定的等离子体条件。该项目旨在通过两次频率加热和频率调谐-束流发射度测量和相应的束流提取计算来改变等离子体条件，从而系统地研究电荷孕育效率和束流质量。此外，CSB将首次用于从离线样品中产生强流光束。CSB育种效率、束流特性和额外的束流生产能力的显著提高将有利于ISAC的实验计划，特别是加速束流实验。第二个方面是培训一般等离子体离子源领域和ECRIS源领域的高素质人员。

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.