On April 9, the top fusion journal Nuclear Fusion received 2 express papers from the J-TEXT team in the Institute of Fusion and Plasma, HUST. There are “Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak” and “Observation of non-local effects in ion transport channel in J-TEXT plasmas”.

The 2 papers of J-TEXT team are co-completed by Energy and Climate Institute of Julich Research Center (Germany) and Seoul National University (South Korea). The express paper of Nuclear Fusion, one of the top journals in the fusion field, shows the latest major innovation in the fusion field that was first published in Nuclear Fusion. On the same day, Nuclear Fusion officially received two express papers from the J-TEXT team, which fully demonstrated the strength of international cooperation and the international impact of research achievements of the International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics of HUST.

It is generally believed that the relationship between the field penetration threshold and density is the linear dependence obtained by empirical calibration. In the paper “Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak” published by Huang Zhuo, a doctoral student co-supervised by Professor Liang Yunfeng and Ding Yonghua, the disentanglement of plasma density and rotation dependences of the field penetration threshold has been first realized, which was based on the experimental results of J-TEXT Tokamak. It shows that the field penetration threshold depends only weakly on the density but linearly on the plasma rotation. This result is not only important for the prediction of error field tolerance in fusion devices, but also presents new opinions on the role of density in the forced magnetic reconnection process in magnetized plasmas.

Figure 1. Comparison of the field penetration threshold (blue dots) and the plasma rotation (red rhombuses). Roll-over densities are obtained where maximums of the plasma rotation and the field penetration threshold are located, indicated by vertical dashed lines.

In the paper entitled Observation of non-local effects in ion transport channel in J-TEXT plasmas published by Professor Shi Yuejiang of Seoul National University and Associate Professor Yang Zhoujun of the J-TEXT team in the Institute of Fusion and Plasma, the non-local transport phenomenon (NLT) of ion channels in magnetic confinement plasma was first discovered on J-TEXT. 35 years ago, K. W. Gentle found NLT of electron transport channel in cold pulse experiments of J-TEXT for the first time. Since then, NLT in electron transport channel has been observed in multiple devices. The emergence of NLT has greatly challenged the traditional plasma transport theory which is based on the local diffusion model. Therefore, many plasma theorists propose various theoretical models to explain NLT. NLT, turbulence and transport characteristics of ion channels found in J-TEXT do not conform to the predictions of several internationally recognized theoretical models. The latest experimental results of NLT in J-TEXT will help to deepen and improve the theory and model of magnetic confinement plasma transport.

Figure 2. The waveforms of cold pulse discharge with multi-pulse SMBI (shot nos. 1057883 and 1057862) in J-TEXT. (a) Line-averaged electron density; (b) core electron temperature; (c) core ion temperature; (d) edge ion temperature at r/a ~ 0.7; (e) edge electron temperature at r/a = 0.69; (f) SMBI pulse signal; (g) edge ion temperature at r/a ~ 0.93; (h) edge toroidal rotation velocity at r/a ~ 0.93.

Paper links:

Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak https://doi.org/10.1088/1741-4326/ab8859

Observation of non-local effects in ion transport channel in J-TEXT plasmas https://doi.org/10.1088/1741-4326/ab8858

Journal introduction:

Nuclear Fusion, sponsored by the International Atomic Energy Agency (IAEA), was founded in 1960. The journal is the acknowledged world-leading journal specializing in fusion. It focuses on the research of heating and confinement of high-temperature plasma, theoretical and experimental exploration of magnetic confinement fusion, technology of thermonuclear fusion reactor and its conceptual design, and has great influence in relevant fields.