The world's first all-HTS tokamak, HH70, has once again set a new benchmark. In its 5,755th shot, it achieved a 1,337-second steady-state long-pulse plasma operation. This milestone was made possible by continuous optimization of its AI-based plasma control system. This marks the first time globally that a fusion device developed and built by a commercial company has successfully sustained a plasma current long-pulse operation at the thousand-second-level.
Launched in November 2025, this campaign on HH70 aimed at steady-state long-pulse plasma operation, with plasma duration exceeding 100 seconds in the 5,319th shot and 300 seconds in the 5,609th shot. Recently, lithium coating of the first wall reduced plasma impurities, while further refinements to the AI control system enabled the final breakthrough.
With this, the campaign concludes—far exceeding our initial 600-second target. Through this campaign, we successfully validated that:
- Our AI-based real-time plasma diagnostics and control technologies significantly boost operational capability;
- The HTS magnets and power supplies remain highly stable under long-duration, complex conditions;
- The RF current drive performs as expected;
- Water-cooled plasma-facing components meet thermal load targets in long runs.
We will analyze the data to optimize the device in preparation for the next experiment campaign.