Progress of HL-2A experiments and HL-2M program

Abstract

Since the last IAEA Fusion Energy Conference in 2018, significant progress of the experimental program of HL-2A has been achieved on developing advanced plasma physics, edge localized mode (ELM) control physics and technology. Optimization of plasma confinement has been performed. In particular, high-N H-mode plasmas exhibiting an internal transport barrier have been obtained (normalized plasma pressure N reached up to 3). Injection of impurity improved the plasma confinement. ELM control using resonance magnetic perturbation (RMP) or impurity injection has been achieved in a wide parameter regime, including Types I and III. In addition, the impurity seeding with supersonic molecular beam injection (SMBI) or laser blow-off (LBO) techniques has been successfully applied to actively control the plasma confinement and instabilities, as well as the plasma disruption with the aid of disruption prediction. Disruption prediction algorithms based on deep learning are developed. A prediction accuracy of 96.8% can be reached by assembling convolutional neural network (CNN). Furthermore, transport resulted from a wide variety of phenomena such as energetic particles and magnetic islands have been investigated. In parallel with the HL-2A experiments, the HL-2M mega-ampere class tokamak was commissioned in 2020 with its first plasma. Key features and capabilities of HL-2M are briefly presented.

Energetic particle marginal stability profile for HL-2M integrated simulation based on neural network module

“…This method can avoid illogical samples that reduce the accuracy of machine learning. To generate a sample, the total pressure and current profiles are assumed according to the HL-2M baseline [26]. On the axis, the density is assumed to be within 5-6 × 10 19 m −3 , and the temperature is within 3-4 keV.…”

Development of a neutron yield measurement system utilizing BF_3 detectors on the HL-3 tokamak

“…The HL-3 tokamak, formerly designated as HL-2M, stands as one of China's most advanced medium fusion devices [15]. Characterized by a major radius (𝑅) of 1.78 m, a minor radius (𝑎) of 0.65 m, and a maximum plasma current of 3 MA, this apparatus integrates three heating and current drive systems, contributing to a total planned power input of 27 MW [16]. This comprises 15 MW from neutral beam injection [17], 8 MW from electron cyclotron resonance frequency, and 4 MW from lower hybrid current drive.…”

ICRF heating schemes for the HL-2M tokamak

“…Particularly, it was missing over 20 years' operation of the HL-2A tokamak. Now our new machine, the HL-2M tokamak, has been built and commissioned successfully to have the first plasma at the end of 2020 [3]. Two upcoming major goals of the HL-2M tokamak are to achieve more than 10 keV ion temperature and to conduct energetic particle studies relevant to burning plasmas [3,4].…”