Evaluation of 4-point probe and eddy current methods as plasma facing components erosion measurement methods

Abstract Impurities resulting from the erosion of plasma-facing components (PFCs) in the plasma chamber disrupt the normal operation of tokamaks. Additionally, continuous erosion leads to the premature aging of these components, affecting their long-term performance and reliability. To quantify erosion and redeposition directly within the machine between operational phases, non-destructive testing methods are crucial. This study evaluates the 4-point and eddy current (EC) methods for measuring the erosion of PFCs and the design of dedicated erosion markers composed of tungsten and alumina multilayers. The 4-point method, sensitive to thickness loss, necessitates electrically insulating layer. Conversely, the EC method requires a conductivity difference between materials but eliminates the need for interlayers. These non-destructive techniques can be effectively integrated into the tokamak to monitor erosion without requiring component removal. Both methods demonstrate potential for accurate thickness measurements. Our results demonstrate that tungsten erosion of less than 2 μ m can be assessed using both the four-point probe and EC methods.