Development of Preloading and Precooling Systems for a Single-Turn Ignition Tokamak

A basic requisite of the Fusion Ignition Experiment (IGNITEX)¹ is the production of a high (20 T) toroidal field (TF) by a single turn coil. The proposed high-field technology uses precooling and preloading systems. The Ignition Technology Demonstration (ITD) program, designed to produce 20 T on axis in a 0.06 scale prototype TF coil, utilizes a preloading structure and a precooling system. The preloading structure is a hydraulic press built around the TF coil, capable of a force of 1.1 Mlb (4.9 MN) and a stroke of 0.5 in. (1.3 cm). The precooling system is an open-top LN₂ cryostat tub integrated into the preload press. The IGNITEX experiment is estimated to use a preload press with force capacity of approximately 150,000 tons (1.3 GN), and with a stroke on the order of 2 in. (5.1 cm). Design considerations include efficient use of material, design of large scale hydraulic actuators, shielding to reduce radiation from activated material, maintenance, cost, and reliability. The precooling system design involves considerations of feedthroughs, minimal cooling time between pulses, maintenance and reliability.