Optimization of the magnetic difference calibration method on Huan Liu-3 tokamak

Blackbody in situ calibration is a standard method for Electron Cyclotron Emission (ECE) diagnostics but involves complex in-vessel hardware that poses maintenance challenges. To provide a robust relative calibration strategy, the Magnetic Difference Calibration Method (MDM) was developed and analyzed on the HL-3 (Huan Liu-3) tokamak under ohmic discharge conditions. Unlike methods requiring internal sources, MDM relies on controlled magnetic field differences between similar discharges, eliminating risks associated with hardware degradation. Based on electron temperature (Te) profiles from the Minute Embedded Tokamak Integrated Simulator code and considering HL-3's plasma displacement control capabilities, an optimized MDM approach was proposed. Results indicate high reliability, with ∼98% accuracy on the low-field side. Compared to traditional absolute calibration methods, the MDM offers a hardware-free approach, making it a valuable complementary technique for ECE calibration.