Dartmouth Events

Abstract

Climate change must be addressed imminently to save biodiversity and human lives. Fusion has enormous potential as a source of safe, carbon-free power, but the current road map seems unlikely to deliver this new energy source in time. However, on September 5^th of this year, the gateway to a significantly accelerated path opened with the demonstration of the world’s first fusion-relevant high-temperature superconducting (HTS) magnet. This 20 Tesla magnet is the cornerstone of the SPARC tokamak, a fusion experiment that is expected to yield up to 140 MW of fusion power with only 11-25 MW required to sustain it. Analogous to the roll out of largescale Covid-19 vaccine production prior to FDA approval, the project moved forward with the engineering design of the tokamak and preparation of the site in Devens, MA prior to the magnet demonstration. Unlike many fusion startup companies, the tokamak physics basis on which SPARC is designed is ~70 years in the making, providing confidence in the predicted output-to-input power ratio of 9-11x, well in excess of the 2x goal. SPARC will burn deuterium and tritium fuel in a toroidal plasma suspended in a vaccum chamber by strong magnetic fields. The circular electromagnets with diameters of up to 8 m will be installed with millimeter tolerances to avoid tearing instabilities, similar to solar flares, that degrade the power production. The strong HTS magnets will improve magnetohydrodynamic stability, but loss of control is still possible and can subject the machine to forces comparable to the thrust of a Falcon-9 rocket and heat intensities exceeding those experienced by the Dragon capsule during reentry. Energetic particle modes are expected in SPARC and minimizing their effect on energetic particle losses will be a research focus aimed at improving fusion performance. The common tokamak core mode responsible for expelling unwanted impurities, known as the sawtooth instability, might also be affected by energetic particles and will be studied. SPARC is funded by private industry, building on the foundations of decades of fruitful, government funded research while harnessing the resources, agility and risk tolerance of the start-up culture.