Speaker: Dr. Caoxiang Zhu, Princeton Plasma Physics Laboratory, Princeton University
Place: Bldg11-413，Yuquan Campus (玉泉校区教11-413室)
Date and time: Tuesday 10am， 10/20/2020（10月20日周二上午10：00）
Abstract: As a fusion concept, the stellarator has attractive properties like low recirculating power and being free of disruptions.
However, stellarators are generally harder to build due to complicated coils. We report recent advances in reducing the coil complexity for optimized stellarators. Three efforts have been dedicated. First, the FOCUS code which uses fully 3-D representations for coils and employs analytically calculated derivatives has been applied in designing coils for new stellarators. FOCUS allows searching for more design space and thus is able to find more possible solutions. Secondly, a Hessian matrix method has been introduced to quickly identify the sensitivity of important error fields to coil deviations. Instead of performing computationally expensive perturbation analysis, the new method can determine the worst scenario by ranking the eigenvalues of the Hessian matrix. Last but not least, the state-of-the-art code,
FAMUS, can determine the optimal layout of the magnets in a given design space. By using permanent magnets, a design of half-Tesla NCSX configuration with only planar TF coils is obtained. These tools/methods can help the design of next-generation stellarators in the U.S. and the construction of an upcoming machine in China.
