Quench dynamics of a HTS cable and potential quench detection systems

Erica Salazar


Tuesday, November 26, 2019



PSFC Student Seminars

High temperature superconductors (HTS) are poised to revolutionize magnetic confinement fusion tokamaks by enabling new high-field tokamak designs that are smaller, cost less, and are faster to build than present low temperature superconductor (LTS) based devices. This advance is facilitated by the high current density and significantly higher fields achieved by HTS when compared to LTS at similar operation conditions.  However, there is little research on quench behavior—when a superconductor transitions from a superconducting to a normal state—in HTS cable systems beyond small scale magnet and tape-level experiments.  The existing HTS tape-level quench studies suggest that quench propagation velocities are orders of magnitude slower compared to LTS.  A slowly spreading normal zone following a local quench may lead to very high temperature (>200 K) localized hot spots that are hard to detect in a large device and can permanently damage the magnet. The consequences of a slow normal zone propagation are a concern to the safety and operation of a superconducting magnet system. Because many high-field tokamak designs consider employing large-bore, high-field HTS magnets for the central solenoid (CS), toroidal field (TF), and poloidal field (PF) magnets, understanding the quench behavior for each magnet system and developing a quench detection system is imperative for reliable operation of the magnet and fusion tokamak system. This presentation will discuss the steps required to 1) experimentally characterize the quench behavior of an HTS cable design 2) extrapolate the test data results using MATLAB to model the thermal hydraulic behavior and quench analysis within a high-field environment and 3) develop a novel quench detection system for the high-field HTS tokamak magnet system