Tokamak Physics Experiment poloidal field design

Abstract

The Tokamak Physics Experiment (TPX) will have a poloidal field system capable of full inductive operation for approximately a 20-s flattop and, with superconducting toroidal and poloidal field coils and non-inductive current drive, it will be capable of true steady-state operation. The poloidal field design is based on the ideal MHD equilibrium model as implemented in the TEQ code developed at LLNL. The PF coils are arranged in an up-down symmetric configuration, external to the TF coils. The TPX diverted plasma will have an aspect ratio of 4.5 and is highly shaped with a nominal elongation of 2 and triangularity of approximately 0.8 as measured at the separatrix. The tokamak design is based on a high-current (q/sub /spl Psi//=3) plasma scenario and a low current scenario. Each scenario has an operational flexibility requirement which is defined as a region of plasma pressure and inductivity (/spl beta//sub N/-l/sub i/) space, where the plasma shape is constrained to keep the divertor configuration operational. Single-null plasma configurations are feasible, even with the same divertor hardware, by operating the PF coils asymmetrically. Recently applied optimization techniques have improved the capability of the PF system without additional cost.