| Nikos Kallinikos |
| The University of Warwick |
Abstract: Symmetries of charged particle motion play an important role in fusion devices. Stellarators, in particular, are based in their majority on the concept of quasisymmetry. The latter is a Hamiltonian symmetry of the reduced system of the guiding center, hence guarantees integrability, which serves as a means to confinement. In this talk, we present necessary and sufficient conditions for its existence and explore their consequences to address involutivity and successively solvability. Using tools from differential geometry, such as moving frames and equivalence transformations, we particularly want to investigate the possibilities of nonisometries and bounded invariants. This is an ongoing effort to prove or disprove stellarator quasisymmetry.