Andrew Jones, 2010, Physics

LTX is a low aspect-ratio tokamak with a heated metal shell designed to be coated with liquid lithium. While magnetic fluxes through diagnostic Mirnov coils and flux loops on the LTX machine yield data which may be used to constrain plasma parameters during reconstruction, the measured signals are often highly sensitive to magnetically induced eddy currents in the conducting shell, and digital integrator circuits introduce error into the gain factors for the sensors.  Over the course of 10 weeks, I created a meshed representation of the conducting metal shell around the LTX machine for implementation into the 2D, axisymmetric LRDFIT code used to reconstruct sensor behavior in the presence of eddy currents. I compared the resultant model-predicted signals to the measured diagnostic signals, as well as to model-predicted signals from LRDFIT in the absence of the conducting shell mesh. I developed and automated a novel calibration method to account for individual sensor gain factors, which may be used on the machine in my absence.  In parallel with my work, a 3D reconstruction code was created to better account for eddy currents; the new calibration procedure will still be applicable to the new system.