Overview of the TCV tokamak program: Scientific progress and facility upgrades

The TCV tokamak is augmenting its unique historical capabilities (strong shaping, strong electron heating) with ion heating, additional electron heating compatible with high densities, and variable divertor geometry, in a multifaceted upgrade program designed to broaden its operational range without sacrificing its fundamental flexibility. The TCV program is rooted in a three-pronged approach aimed at ITER support, explorations towards DEMO, and fundamental research. A 1 MW, tangential neutral beam injector (NBI) was recently installed and promptly extended the TCV parameter range, with record ion temperatures and toroidal rotation velocities and measurable neutral-beam current drive. ITER-relevant scenario development has received particular attention, with strategies aimed at maximizing performance through optimized discharge trajectories to avoid MHD instabilities, such as peeling-ballooning and neoclassical tearing modes. Experiments on exhaust physics have focused particularly on detachment, a necessary step to a DEMO reactor, in a comprehensive set of conventional and advanced divertor concepts. The specific theoretical prediction of an enhanced radiation region between the two X-points in the low-field-side snowflake-minus configuration was experimentally confirmed. Fundamental investigations of the power decay length in the scrape-off layer (SOL) are progressing rapidly, again in widely varying configurations and in both D and He plasmas; in particular, the double decay length in L-mode limited plasmas was found to be replaced by a single length at high SOL resistivity. Experiments on disruption mitigation by massive gas injection and electron-cyclotron resonance heating (ECRH) have begun in earnest, in parallel with studies of runaway electron generation and control, in both stable and disruptive conditions; a quiescent runaway beam carrying the entire electrical current appears to develop in some cases. Developments in plasma control have benefited from progress in individual controller design and have evolved steadily towards controller integration, mostly within an environment supervised by a tokamak profile control simulator. TCV has demonstrated effective wall conditioning with ECRH in He in support of the preparations for JT-60SA operation.

TCV托卡马克（tokamak）正通过一项多维度升级计划，在不牺牲核心灵活性的前提下拓展运行范围，新增离子加热系统、适配高密度条件的额外电子加热模块以及可变偏滤器（divertor）构型，以强化其既有独特历史优势：强塑形能力与强电子加热能力。TCV的研究计划依托三大核心方向：支撑国际热核聚变实验堆（ITER）、探索示范聚变堆（DEMO）以及开展基础研究。近期，一台1兆瓦切向中性束注入器（neutral beam injector, NBI）完成安装，迅速拓展了TCV的参数区间，实现了创纪录的离子温度与环向旋转速度，并可实现可测量的中性束电流驱动。与ITER相关的运行场景开发受到重点关注，研究策略旨在通过优化放电轨迹避免磁流体动力学（magnetohydrodynamics, MHD）不稳定性——如剥离-气球模与新经典撕裂模——以最大化装置性能。等离子体排气物理实验重点聚焦于脱附现象——这是示范聚变堆（DEMO）商业化应用的必要环节——并覆盖了传统与先进偏滤器构型的全面研究。低场侧雪花负型（snowflake-minus）构型中双X点间存在增强辐射区的理论预测，已通过实验得到验证。刮削层（scrape-off layer, SOL）内功率衰减长度的基础研究进展迅速，研究覆盖了多种构型以及氘（D）、氦（He）等离子体；尤其值得注意的是，在高SOL电阻率条件下，低约束模（L-mode）限制等离子体中原本的双衰减长度特征被单衰减长度取代。针对大剂量气体注入与电子回旋共振加热（electron-cyclotron resonance heating, ECRH）的破裂缓解实验已全面启动，同时同步开展了稳定与破裂工况下的逃逸电子产生与控制研究；部分工况下已观测到携带全部装置电流的稳态逃逸束流。等离子体控制技术的发展得益于单一控制器设计的进步，并逐步向控制器集成方向演进，相关研究大多依托托卡马克剖面控制模拟器进行监督管控。TCV已成功验证了利用氦（He）等离子体结合ECRH实现的有效壁处理技术，为JT-60SA的运行筹备提供了支撑。