The Experimental Advanced Superconducting Tokamak (EAST) in Hefei, China, has set a new world record for high-confinement mode (H-mode) plasma duration. Scientists at the Hefei Institutes of Physical Science sustained a fully non-inductive, steady-state plasma for 403 seconds. This achievement, part of the 2023 experimental campaign, significantly surpasses the previous record of 101 seconds set by EAST in 2017. The result demonstrates progress in controlling plasma instabilities and managing heat exhaust over extended timescales, which are critical challenges for future fusion power plants. The experiment is a key step in validating the physics and engineering principles required for next-generation devices like the International Thermonuclear Experimental Reactor. Source: ITER

Sustaining a plasma in H-mode is essential for achieving the conditions necessary for net energy gain. This high-performance regime features significantly improved energy confinement compared to the standard low-confinement (L-mode) operation. However, H-mode plasmas are susceptible to edge localized modes (ELMs), which can release damaging bursts of energy onto plasma-facing components. The 403-second discharge at EAST successfully integrated control over plasma-wall interactions, power and particle exhaust, and confinement. This long-pulse operation provides a valuable platform for studying the physics of steady-state H-modes and testing divertor technologies under reactor-relevant conditions. Source: ITER

Sustaining a plasma in H-mode is essential for achieving the conditions necessary for net energy gain.

EAST is a fully superconducting tokamak designed specifically to explore the scientific and engineering issues of advanced, steady-state fusion reactors. Its mission is to test technologies and operational scenarios directly relevant to ITER and the planned China Fusion Engineering Test Reactor (CFETR). The recent record was achieved by optimizing plasma shape control, radio-frequency heating, and current drive systems. The ability to maintain stable conditions for hundreds of seconds allows researchers to investigate phenomena that evolve on slow timescales, such as the migration of impurities and the evolution of material surfaces, which cannot be studied in short-pulse experiments. Source: ITER

This result contributes to a growing body of data from long-pulse superconducting tokamaks worldwide, including South Korea's KSTAR and Japan's JT-60SA. While this experiment focused on duration rather than maximizing the fusion triple product, the demonstrated control over a high-performance plasma for over six minutes is a significant operational milestone. The data gathered from this record-setting shot will inform the operational plans for ITER, which aims to sustain burning plasmas for 300-500 seconds. The next steps for the EAST team will involve analyzing the vast dataset from the discharge and preparing for future experiments aimed at integrating high plasma performance with even longer pulse durations. Source: ITER