It’s not every day that a company specializing in software solutions for tolerance analysis gets to supply an international project to build the world’s largest tokamak. But that’s what Troy, Michigan’s Dimensional Control Systems has been doing. The goal of the ITER (International Thermonuclear Experimental Reactor) tokamak project is to advance the science of fusion energy and explore its capabilities for future commercial use. The project members – China, the European Union, India, Japan, Korea, Russia and the United States – have collaborated to assemble the largest tokamak ever constructed, a prototype for future energy production across the globe. As designs evolve into the building of the machine and housing complex, there is a need for tools that analyze and predict assembly variation based on component tolerance, piece part geometry, and locating schemes.
What exactly is a tokamak? The name derives from a Russian acronym for “toroidal chamber with magnetic coils.” The tokamak was developed by Soviet research in the 1960s. It is a doughnut-shaped vacuum chamber that uses the process of fusion to produce energy. This is the same process by which the stars and sun produce heat and light. Hydrogen nuclei collide in the heat and gravity of those bodies, fuse into helium atoms and release tremendous amounts of energy. Within a tokamak, reactions of hydrogen isotopes deuterium and tritium under extreme heat (150,000,000° Celsius, 10 times the temperature of the sun) produce plasma that is maintained at the necessary temperatures and structured by magnetic fields. These fields are a toroidal field generated by external coils surrounding the vessel, a helicoidal field generated by the plasma flow around the torus center and a poloidal field that fixes the position of the plasma flow away from the chamber walls. It is this concept of magnetic confinement that defines the machine as a tokamak.