This paper summarizes the physical principles behind the novel three-ion scenarios using radio frequency waves in the ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexible ICRF technique for ion cyclotron heating and fast-ion generation in multi-ion species plasmas. The theoretical section provides practical recipes for selecting the plasma composition to realize three-ion ICRF scenarios, including two equivalent possibilities for the choice of resonant absorbers that have been identified. The theoretical findings have been convincingly confirmed by the proof-of-principle experiments in mixed H–D plasmas on the Alcator C-Mod and JET tokamaks, using thermal ³He and fast D ions from neutral beam injection as resonant absorbers. Since 2018, significant progress has been made on the ASDEX Upgrade and JET tokamaks in H–⁴He and H–D plasmas, guided by the ITER needs. Furthermore, the scenario was also successfully applied in JET D–³He plasmas as a technique to generate fusion-born alpha particles and study effects of fast ions on plasma confinement under ITER-relevant plasma heating conditions. Tuned for the central deposition of ICRF power in a small region in the plasma core of large devices such as JET, three-ion ICRF scenarios are efficient in generating large populations of passing fast ions and modifying the q-profile. Recent experimental and modeling developments have expanded the use of three-ion scenarios from dedicated ICRF studies to a flexible tool with a broad range of different applications in fusion research.

中文翻译：

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三离子ICRF场景在聚变研究中的物理和应用

本文总结了在离子回旋加速器频率范围（ICRF）中使用射频波的新型三离子场景背后的物理原理。我们讨论了如何将模式转换电子加热转换为一种新的灵活的ICRF技术，用于在多离子物种等离子体中进行离子回旋加速器加热和快速离子生成。理论部分提供了选择等离子体成分以实现三离子ICRF方案的实用方法，包括已确定的两种等效选择共振吸收器的可能性。理论上的发现已经通过在Alcator C-Mod和JET托卡马克上使用热³混合H-D等离子体进行的原理验证实验得到了令人信服的证实。他和来自中性束注入的快速D离子作为共振吸收剂。自2018年以来，在ITER的要求下，H- ⁴ He和H-D等离子体的ASDEX升级和JET托卡马克取得了重大进展。此外，该方案还成功应用于JET D– ³ He等离子体中，作为一种产生融合生成的α粒子的技术，并研究了快速离子对与ITER相关的等离子体加热条件下的等离子体约束的影响。为在大型设备（如JET）的等离子核中的小区域集中沉积ICRF功率而进行了调整，三离子ICRF方案可有效地产生大量快速离子通过并改变q值。-轮廓。最近的实验和模型开发已经将三离子方案的使用从专用的ICRF研究扩展到了在融合研究中具有广泛不同应用的灵活工具。