The Design and Development of Compact Toroid Injection System to Study Reconnection Dynamics in MST

Abstract

This thesis details the design and development of an experimental setup to investigate compact toroid (CT) dynamics in tokamak plasmas, specifically on the MST device. The research aims to better understand how a CT traverses through a tokamak and poten- tially find evidence of ion energization at reconnection. A significant component of the project is a 3D simulation framework to model CT trajectories in a tokamak environment. This simulation, based on an extended conducting sphere model, uses MATLAB to solve a system of ordinary differential equations that are derived from a six degree of freedom (6-DOF) Lagrangian. The simulations determine optimal CT injection parameters for the experiments and facilitate parametric studies of various gas species. The initial experi- mental design adopts a tangential injection approach using helium CTs, chosen for their detectable line radiation with ion-Doppler spectroscopy. Upgrades to the CT injector’s charging circuit and control software have been implemented to meet MST operating pro- tocols and improve operability. Key improvements include the addition of vacuum relays to isolate the charging supply during capacitor discharge, integration of bleed resistors for enhanced safety, reconfiguration of the CompactRIO industrial controller with new modules, implementation of new relay logic in LabVIEW, and rewiring of the CTI rack to accommodate additional components. This work establishes a foundation for future investigations into tokamak plasma reconnection dynamics, with particular emphasis on CT injection and its effects on plasma behavior.