W. Lau
LAU Superconductors Inc.,
United States
Keywords: high temperature superconductors, HTS, liquid nitrogen
Summary:
There has been a breakthrough in strengthening the brittleness of High Temperature Superconductors (HTS) which should lead to the widespread use of liquid nitrogen cooled superconductivity in existing products such as electric power Superconducting Fault Control Limiters (SFCL), as well as new applications such as magnetic projectile launching for missiles and spacecraft. Magnetic launching is silent and more efficient than rockets. It does not create an infra-red heat signature detectable by current technology. Opponents could in theory launch a first nuclear strike eroding a longstanding Mutually Assured Destruction (MAD) nuclear deterrent leading to a renewed nuclear arms race. Current Low Temperature Superconductors (LTS) require extremely cold liquid helium (He) to operate at temperatures near to those of outer space. Liquid He is difficult to handle and increasingly expensive. This has limited superconductor use to medical Magnetic Resonance Imaging (MRI) and SFCLs. HTS operate at the much higher temperatures of liquid nitrogen (N). Liquid N is cheap and used widely in doctor's offices and restaurants. But HTS is not widely used because it is a ceramic single crystal which breaks easily. Once broken, HTS stops superconducting. “A simple, reliable and robust reinforcement method for the fabrication of (RE)–Ba–Cu–O bulk superconductors¨ Devendra K Namburi, Kaiyuan Huang, Wayne Lau, Yunhua Shi, Kysen G Palmer, Anthon R Dennis, David A Cardwell and John H Durrell, 30 March 2020, Superconductor Science and Technology, Volume 33, Number 5 demonstrates the use of long silicon carbide (SiC) fibers to reinforce single crystal HTS. This is like how straw reinforces mud to make bricks. Only three hair sized SiC fibers boosted strength in a one inch HTS sample by 40%. Earlier attempts to reinforce HTS failed because HTS is made by first melting component powders at ≈ 1200°C, then cooling under oxygen to form a single crystal. Reinforcing material placed inside oxidizes at high temperatures, forming impurities which interrupts crystal growth which weaken strength. Our concept is that the silicon in SiC fibers reacts at high temperatures with oxygen creating a layer of inert silicon dioxide (beach sand) preventing further oxidation. This passivation is similar to how chromium makes steel stainless and how aluminium can be used for pots and pans. Stronger HTS should lead first to replacement of liquid He cooled LTS in existing SFCL and MRI markets, then to replacing old technology such as hydraulics in aircraft control[,][remove comma] and rockets for launching missiles and spacecraft. Eventually there will be new applications such as radiation shields to protect satellites and space stations from solar charged particle storms - a leading cause of satellite failure. In the future, superconductor magnetics may allow the economic integration of Space-based Solar Power with a Space Elevator providing both sustainable power as well as efficient access to outer space.