Commercial compact fusion triggered REBCO tape industry: Pulsed laser deposition technology opportunities and challenges

Advance Snapshot:

Commercial compact fusion promotes rapid development of PLD-REBCO industry

Research Motivation:

Commercial compact fusion has significantly driven the development of the PLD-REBCO industry, making technological advancements and economies of scale urgently needed to improve the cost-performance ratio of REBCO tapes.

Background

REBCO tapes are among the most promising high-temperature superconducting materials and are critical for commercial compact nuclear fusion reactors. Key fundamental issues of PLD-REBCO technology have been extensively studied, and dynamic high-speed deposition technologies for industrialization are rapidly evolving.

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Industrial Progress of PLD-REBCO

Currently, there are approximately 15 HTS tape manufacturers worldwide, with an annual production capacity exceeding 5,000 km (12 mm width). Among them, four top-tier manufacturers adopt the PLD route: FFJ (Japan), Shanghai Superconductor Technology (China), Fujikura (Japan), and S-innovation (Russia). These four manufacturers contribute more than half of the global total production. Additionally, new manufacturers such as HTSI (USA), SuperMag Technology (China), Suprema (Italy), and traditional manufacturers like SuNAM (South Korea) and SuperPower (USA) are also transitioning to PLD technology.

Each manufacturer has its own technological preferences, with main differences lying in the heating and drive systems of the vacuum chamber, categorized into flat-plate and drum types. Both configurations are capable of producing highly uniform long-length REBCO tapes. Mass-produced PLD-REBCO tapes have achieved J_e exceeding 1,000 A/mm² @ 20 K, 20 T, demonstrating excellent in-field performance (I_c>200 A/4 mm @ 20 K, 20 T, B//c) and competitive pricing ($15–30/m).

Opportunities

The progress in industrial-scale HTS tapes using PLD technology has far exceeded expectations from scientists or laboratory research. The extensive application of PLD-REBCO tapes in large-scale demonstration projects provides vast amounts of data for further iterative optimization. This not only improves the performance, homogeneity, and yield of industrial HTS tapes but also significantly boosts industry confidence. From an industrial perspective, further scaling and improved reproducibility are still needed. PLD does not require modulating complex chemical reactions, simplifying process control. Economically, PLD technology facilitates equipment replication, attracting new manufacturers to adopt it or existing production lines to expand.

Challenges

The cost of REBCO tapes must continue to decrease, with a short-term target of $50/kA·m and a long-term goal of $10–20/kA·m. To achieve this, scaling up production is necessary. FFJ and Shanghai Superconductor have demonstrated the feasibility of scaling through replication and expansion of existing production lines. However, several technical challenges remain. First, the costs of high-power excimer lasers and raw materials account for a significant portion and directly affect tape performance. Improving laser efficiency (current produced per unit energy, A/Joule) is crucial. Low utilization rates of REBCO targets (<50%) and long delivery cycles also pose additional challenges. Second, how to widen the optimal deposition process window remains an unresolved scientific and engineering issue. Additionally, effective online monitoring, feedback, and control technologies need to be developed. The introduction of AI-based data mining is expected to further enhance stability.

Conclusion and Future Perspectives:

PLD technology shows great potential for the large-scale production of high-performance REBCO tapes, particularly in meeting the growing demand for high-temperature superconducting materials from compact fusion applications. In the future, closer collaboration between industry and academia should be established to jointly address the scientific and engineering challenges in its industrialization.