## Scientific Computing and Numerics (SCAN) Seminar

For several scientific applications, one wants to invert the Biot-Savart Law of magnetostatics: given a desired magnetic field in some region, what are electromagnetic coils outside the region to produce this field? This problem arises in magnetic resonance imaging, particle accelerators, and magnetic fusion energy. In the latter area, the inverse Biot-Savart problem is central to the stellarator concept, in which non-axisymmetric fields confine plasmas in steady state. In this talk, several algorithms for this problem of stellarator electromagnet design are discussed. One is a new method of topology optimization for electromagnets, in which algorithms for sparse regression can be exploited. We also examine how far away the magnets can be from the target volume, and how this distance can be understood from a physical argument involving scale lengths.