Speaker
Description
High-temperature superconductors (HTS) are increasingly being used to build
electromagnets to generate strong magnetic fields for a wide range of applications,
from medical devices and electric motors to future fusion reactors. These
superconductors are subject to quenching, a phenomenon that manifests itself as a
rapid rise in the temperature of the HTS material, leading to a loss of the
superconducting state and interruption of magnet operation. The timely and rapid
detection of the quenching is currently one of the most active areas of development.
A technique based on frequency and time domain reflectometry (FTDR) is suggested
in this presentation for the quench monitoring. We use the detection and analysis of
microwave electromagnetic signals propagating in the coolant gas channels to monitor
the temperature of the coolant enabling the quench monitoring. The techniques
suggested should allow both a real-time quench detection capability, as well as,
facilitating the acquisition of valuable information regarding the health of the whole
magnet system throughout its operation time.
The methodology presented here is based on the established correlations between
thermodynamic gas variables such as temperature and pressure with its
electromagnetic properties i.e. refractive index. The technique has been recently
subjected to both numerical and experimental validations. Numerical simulations were
conducted using CST Microwave studio and it was found that a localised hotspot can
be detected with minimal time delay, a crucial consideration for systems necessitating
rapid response monitoring for safety purposes. The experimental data observed agree
well with the theoretical understandings and it will be presented. While the technique
holds significant potentials for quench monitoring it also offers valuable opportunities
to develop new monitors in areas encompassing many devices which are applying
complex gas cooling, such as fusion reactors, MRI systems and others.
