Construction of MUSE Permanent Magnet Stellarator and Error Field Measurement Using Electron Beam Mapping

MUSE is the world's first quasi-axisymmetric stellarator constructed with planar circular coils and permanent magnets. The components manufacturing, sub-systems tests, quarter assembly and vacuum vessel assembly have been completed over the past year. Detailed procedures have been developed in order to complete MUSE successfully. Final assembly is underway.

Electron beam mapping of the flux surfaces will be conducted after the assembly to study error fields and adjust the position of the permanent magnets to minimize errors. By comparing the shape of the flux surfaces with the numerical models, the permeability of the permanent magnets will be calibrated and the position of the PM(permanent magnet) holders will be adjusted to maximize the agreement. A subsequent study of the island width on 2/10, 2/11 and 2/12 island chains on configurations with lower coil current will be conducted to quantify the field errors.