Abstract: This talk motivates the study of using optimized stellarators to link large volume axisymmetric mirrors for the purpose of fusion energy.
There are significant challenges in scaling optimized stellarators to fusion reactors, in particular the construction of a large volume 3D device which has a breeding blanket integrated with complex geometry. Meanwhile, mirrors have large volume and simple coils, but face plasma physics issues due to open field line end loss, velocity space anisotropy, MHD stability, and turbulence (once confinement allows sufficiently high temperature gradients).
We propose a hybrid approach that overcomes challenges of each, enabled by modern stellarator optimization. It consists of axisymmetric mirror cells linked by stellarator segments. Most of the plasma volume is in the mirror cells, where the typical loss cone is replaced by a source cone from the stellarator. The goal is to combine the simple engineering of axisymmetric, linear mirror cells with the good plasma confinement and stability of stellarators.
Two questions arise: do such flux surfaces exist? If so, are they MHD stable? We discuss a basic plasma physics experiment that can be built to address these questions using the unique capabilities at UW-Madison.