Physicist Elizabeth Paul and Matt Landreman with figures behind them. (Credits: Arthur Lin for Paul photo, Faye Levine for Landreman photo; top left and right figures from PRL paper; bottom computer-generated visualizations of a tokamak, left, and a stellarator, right by Paul and Landreman. Collage by Kiran Sudarsanan.)
Scientists have achieved a new breakthrough in the conceptual design of stellarators, experimental magnetic facilities that produce fusion energy – the nuclear reaction that powers the sun and stars.
This breakthrough shows how to shape the enclosing magnetic fields more precisely in stellarators to create an unprecedented ability to hold fusion fuel together.
Stellarators were developed in the 1950s but have taken a back seat to tokamaks — complex, donut-shaped devices. One of the reasons for this is that stellarators have had a difficult time confining the paths of the ions and electrons that swirl around during the fusion process. This causes a large and sustained loss of the extreme heat required to bring the ions together to release fusion energy.
As outlined in a recent paper in Physical Review Letters, the scientists were able to precisely create what is called “quasisymmetry,” which is a way of confining the paths of ions and electrons. To do this, the scientists used new open-source software called SIMSOPT (Simons Optimization Suite) that is designed to optimize stellarators by slowly refining the simulated shape of the boundary of the plasma that marks out the magnetic fields.