Reinforced High Temperature Superconductors for Nuclear Fusion?

W.C.W. Lau
LAU Superconductors,
United States

Keywords: Superconductors, High Temperature Superconductors, HTS, Nuclear Fusion, Energy


Several promising projects for magnetic confinement nuclear fusion (e.g. Commonwealth Fusion US, and Tokomak Energy UK) use the strong magnetic fields of High Temperature Superconductors (HTS). Until now, they have relied on HTS tapes made by chemically depositing thin, poly-crystalline layers on a metal substrate. HTS tapes suffer from a) complicated manufacturing processes needing b) stringent quality control and c) limited current capacity. This creates supply issues. Projected fusion demand already exceeds HTS tape manufacturing capacity. Major HTS tape makers are also located in embargo sensitive areas. HTS tapes were developed because single crystal HTS was too brittle for most practical uses. To address brittleness, we innovated a method to reinforce HTS with Silicon Carbide (SiC) fiber (A simple, reliable and robust reinforcement method for the fabrication of (RE)–Ba–Cu–O bulk superconductors, Devendra K Namburi et al 2020 Supercond. Sci. Technol. 33 054005, DOI 10.1088/1361-6668/ab7ec4. Internal reinforcement boosted strength by 40% with only three hair-sized SiC fibers in a one inch HTS sample. Fiber reinforcement adds strength to HTS like steel rebars add strength to reinforced concrete. Previous attempts to add reinforcement failed because of HTS’ harsh production process: powders are melted at high temperatures (≈1200°) then crystalized under oxygen. Added reinforcement oxidized creates impurities which contaminate the HTS single crystal making it weaker. SiC does not contaminate HTS because silicon in SiC reacts with oxygen to create a durable coat of silicon oxides preventing further oxidation. This passivation process is how chromium added to steel makes stainless steel, and how normally reactive aluminum can be used in pots and pans. Can reinforced HTS be used in nuclear fusion? Two issues arise: 1) HTS is anisotropic unlike low temperature superconductors and conventional metal conductors. This means that HTS crystal planes must be oriented along the conduction axis of electric current. 2) Reinforced HTS may be too stiff to wind into solenoids unlike more flexible HTS tapes. A solution would be to use the enhanced strength of reinforced HTS to create single crystal blocks with suitable conduction planes. Appropriate HTS geometries could then be cut from such blocks for use in nuclear fusion. Dear TechConnect Team I am scheduled for the following Poster Presentation: Monday, June 19, Advanced Materials for Engineering Applications – Posters Expo Hall AB, ¨Superconductors in Space @ Ambient Temperature for Boost-Phase Missile Interception¨, W.C.W. Lau, LAU Superconductors, US My innovation #2143, Nuclear Deterrence: Boost Phase Missile Interception with Superconductors in Space has just been accepted to be showcased at the Demo and Drinks section at the TechConnect World Exhibition Reception. If the Reinforced HTS for Nuclear Fusion poster is attractive, would you prefer: a) to replace my Superconductor in Space Poster with my Reinforced HTS in Nuclear Fusion Poster or b) have both posters? If both Posters, I could present two Posters during the session as long as they were reasonably close to each other (ideally next to each other). Sincerely Wayne