[L1] 1 Overview of Superconductor [L2] 1) Definition [L4] - A material that loses all electrical resistance below a certain temperature called the superconducting transition temperature (Tc). [L5] * The electrical resistance of metallic conductors decreases as temperature decreases, but superconductors become perfect conductors with zero resistance when cooled below the transition temperature. [L4] - A superconductor must meet the condition of zero electrical resistance and possess the Meissner effect to be called a superconductor. [L5] * An object with no electrical resistance but without the Meissner effect is called a perfect conductor. [L2] 2) Features [L4] - Current can flow infinitely without energy loss. [L4] - Meissner Effect: A phenomenon of expelling external magnetic fields below Tc. This is the ability to levitate a magnet above a superconductor. [L5] * Superconductors exhibit two types of Meissner effects depending on the material: Type-1 which expels magnetic fields, and Type-2 which allows magnetic flux pinning (fixing material above the magnetic field). [L4] - The superconductivity phenomenon is explained through the BCS theory. [L1] 2 Development of Superconductors [L2] 1) Discovery [L4] - First discovered by Dutch physicist Onnes in 1911. [L5] * He developed liquid nitrogen, and later discovered it through cryogenic experiments using liquid nitrogen on materials. [L2] 2) Development History [L4] - Until 1986, Nb3Ge was the highest temperature at 23.2K, but through continuous development, 6,000 types of superconductors are currently known. [L4] - Currently, materials with the highest temperature of 139K have been developed. [L2] 3) Direction of Superconducting Objects [L4] - Cryogenic superconductors are difficult to utilize due to cooling issues. Development aims to raise Tc to near room temperature. [L4] - With the discovery that simple element (Hydrogen) compounds can induce superconductivity when solidified, superconductors are currently being studied under conditions constituting a high-pressure environment to increase Tc. [L1] 3 Applications of Superconductors [L2] 1) Perfect Conductor Ability [L4] - Superconducting magnets can be made and are utilized in Magnetic Resonance Imaging (MRI). [L4] - Energy efficiency is maximized as there is no power loss in long-distance power transmission. [L4] - Since there is no resistance, there is no heat generation, allowing the development of electronic devices with low power consumption and no need for cooling equipment for heat generation. [L2] 2) Meissner Effect [L4] - Magnetic Levitation Trains (Maglev) can be developed by eliminating friction through magnetic levitation. [L4] - Used in manufacturing magnets that bend the path of charged particles in high-speed particle accelerators. [L4] - In nuclear fusion devices (Tokamak), superconducting currents are used to create super-strong magnets to confine internal high-temperature plasma, enabling nuclear fusion with low input.