Eddy current characterization on material surface during high power application – A benchmark experiment

• Main Authors: Sebastian, Arun, Thomas, Polly
• Format: Conference Proceeding
• Language: English
• Subjects: Eddy current; High power Application; Metallic Surface; Non Destructive Test; Rogowski Coil; Torus
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2021.09.180

Eddy current is creating a lot of problems in high voltage and high current experiments. High eddy current can cause significant heating and deteriorating electromagnetic forces on mechanical structures. The strange behavior of eddy current will sometime leads to collapse of mechanical structures in large experimental set ups. Measurement of eddy current is very important in cases where its magnitude exceeds a certain value. Here we suggest a benchmark experiment for measuring eddy current developed on a metallic surface during a high current discharge. In this experiment, a torus shaped steel (SS 304) tube is considered which resembles super conducting reaction chamber used in fusion experiments. These experiments are under high power applications and hence the mechanical structure will be subjected to eddy current impacts which needs to be studied well in early to understand the possible after effects. Results from a benchmark experiment with similar prototype will help in such situations to derive the system parameters under actual experiment situations. Here, coil is inserted through the torus and a high current discharge is given through that coil using a capacitor and thyristor control circuit. Due to this high current discharge, eddy current will be developed on the torus surface. Practical measurement of current discharged can be calculated using a calibrated Rogowski coil. Another calibrated Rogowski coil is wound across the torus structure to pick the eddy current. Rogowski coil will give the di/dt value. Integrating the output will give the value of current. Subtracting the two Rogowski coil output will give the eddy current value. Further, the experimental set up is modeled and simulated in ANSYS MAXWELL and eddy current obtained from simulation is compared with those we obtained practical values. The proposed experimental setup is a Non Destructive Test (NDT) and therefore this can be easily executed in any test atmosphere. The validated method finds its application in particle accelerators and fusion research.