In the quest for cleaner, more efficient nuclear fusion energy, scientists are constantly pushing the boundaries of what’s possible. A recent study published in ‘Nuclear Fusion’ has shed new light on the optimization of stellarator magnetic fields, a critical component in the development of fusion reactors. The research, led by F.J. Escoto of the National Fusion Laboratory at CIEMAT in Madrid, Spain, focuses on a specific type of magnetic field configuration known as quasi-isodynamic (QI) fields.
Stellarators, a type of fusion device, use complex magnetic fields to confine hot plasma, but they are notoriously difficult to optimize. The goal is to minimize neoclassical transport, a process that can cause energy and particles to leak out of the plasma, reducing the efficiency of the reactor. QI fields are a subset of omnigenous magnetic fields, which are designed to have levels of radial neoclassical transport comparable to tokamaks, another type of fusion device. The key advantage of QI fields is that they produce zero bootstrap current, a self-generated electric current that can cause instabilities in the plasma.
Escoto and his team used a newly developed code called MONKES to evaluate a large database of intermediate configurations that led to the development of the CIEMAT-QI configuration. MONKES enables fast computations of neoclassical radial transport and bootstrap current monoenergetic coefficients, making it a powerful tool for assessing the efficiency of optimization strategies.
The study revealed that the indirect optimization strategy, which minimizes proxies that vanish in an exactly QI field, is not as efficient as previously thought. “Our results show that the indirect approach does not always lead to the best outcomes,” Escoto said. “This is a significant finding because it challenges the conventional wisdom in the field and opens up new avenues for research.”
But the research doesn’t stop at QI fields. The team also used MONKES to explore a novel family of optimized magnetic fields known as piecewise omnigenous fields. These fields broaden the configuration space of stellarators with low levels of radial neoclassical transport, potentially leading to more efficient and stable fusion reactors.
The implications of this research are far-reaching. By improving our understanding of stellarator optimization, we can move closer to the goal of sustainable, clean nuclear fusion energy. This could revolutionize the energy sector, providing a virtually limitless source of power with minimal environmental impact.
As Escoto puts it, “The development of more efficient stellarator configurations is a crucial step towards making fusion energy a reality. Our work with MONKES is a significant step in that direction, and we hope it will inspire further research in this exciting field.” The study, published in ‘Nuclear Fusion’, is a testament to the ongoing efforts to harness the power of the stars here on Earth.
