Abstract

Cryogenic pellets are used for injection into fusion plasmas to add fuel to build up density and replace the ions lost from fusion reactions and imperfect confinement in the plasma. These pellets are formed at cryogenic temperatures with pure hydrogenic isotopes or mixtures of the isotopes. Technology to make these pellets and inject them into plasmas has been under development for many years, and various methods using freezing or desublimation have been shown to produce high-quality solid pellets suitable for injection. The throughput needed and possible impurity content from the necessary recirculation of fusion exhaust gases are two of the key issues to overcome for fusion pellet fueling systems in long-pulse burning plasmas. Here, we describe the technical challenges associated with these issues and the capability of pellet formation extruders to overcome them.

Cryogenic pellets of deuterium, neon, and argon are also used in fusion tokamak devices for disruption mitigation in the form of large pellets that can be injected on demand to quickly dissipate the plasma thermal energy through radiation and add significant density in order to prevent runaway electron formation. Here, the issue is not throughput as with the fueling pellets but rather is the time it takes to form pellets of the size needed and the ability to dislodge them immediately on demand when needed to mitigate a disruption. The method used to make these pellets by desublimation is described, and examples related to how pellet size and input gas parameters affect the formation time are provided.

摘要

低温颗粒用于注入聚变等离子体以增加燃料以增加密度并替换因聚变反应和等离子体中的不完善限制而损失的离子。这些小球是在低温下用纯氢同位素或同位素混合物形成的。制造这些颗粒并将其注射到等离子体中的技术已经开发多年，并且已经证明使用冷冻或凝华的各种方法可以生产适合注射的高质量固体颗粒。聚变废气的必要再循环所需的吞吐量和可能的杂质含量是长脉冲燃烧等离子体中聚变颗粒燃料系统需要克服的两个关键问题。这里，

氘、氖和氩的低温小球也用于聚变托卡马克装置，以大小球的形式减轻破坏，可按需注入，通过辐射快速消散等离子体热能，并增加显着的密度，以防止电子失控形成。在这里，问题不在于燃料芯块的吞吐量，而是形成所需尺寸的芯块所需的时间，以及在需要时根据需要立即移除它们以减轻中断的能力。描述了用于通过凝华制造这些球团的方法，并提供了与球团大小和输入气体参数如何影响形成时间相关的示例。