Abstract Details
Abstracts
Author: Lanke Fu
Requested Type: Poster
Submitted: 2023-03-27 15:06:42
Co-authors: E. Rodríguez, A. Bhattacharjee
Contact Info:
PPPL
100 Stellarator Road
Princeton, New Jersey 08540
United States
Abstract Text:
The Garren-Boozer conundrum suggests that equilibrium with global quasi-symmetry (QS) probably does not exist under MHD with isotropic pressure. When expanded as power series of effective distance from magnetic axis, the governing equations become over-determined at the 3rd order. [1] However, this does not forbid the existence of special solutions, and recent optimization works have indeed found a few isotropic-pressure equilibria with precise global QS.[2] Rodriguez and Bhattacharjee have shown that introducing a pressure anisotropy allows the construction of global weak QS to arbitrarily high order. [3] This raises the question whether the expansion for anisotropic pressure to all orders is convergent or asymptotic.
We present pyAQSC, the first numerical code for the near-axis expansion of anisotropic pressure QS equilibria to any order, and the full symbolic expression of the ordered equation sets to any order. Our numerical results show that in all examined cases, the expansion diverges after the 4th order, consistent with the good accuracy observed in 2nd order, scalar pressure expansions. [4] As the first numerical near-axis expansion tool that incorporates pressure anisotropy, our code can explore new possibilities in the QS equilibrium configuration space. Along with a new equilibrium solver developed under the rubric of the DESC code, it provides a powerful and efficient computational tool to explore new stellarator designs in the QS configuration space.
References
1. Garren, D. A., & Boozer, A. H. (1991). Physics of Fluids B: Plasma Physics, 3(10), 2822–2834. https://doi.org/10.1063/1.859916
2. Landrema, M. & Paul, E. (2022). Physical Review Letters, 128, 035001. https://doi.org/10.1103/PhysRevLett.128.035001
3. Rodríguez, E., & Bhattacharjee, A. (2021a). Physics of Plasmas, 28(1), 012508. https://doi.org/10.1063/5.0027574
4. Landreman, M. (2019). Plasma Physics and Controlled Fusion, 61(7), 075001. https://doi.org/10.1088/1361-6587/ab19f6
Comments:
Co-author affiliation:
Eduardo Rodríguez/2/, and Amitava Bhattacharjee/1/
1.Princeton Plasma Physics Laboratory, Princeton University
2.Max Planck Institute for Plasma Physics, Greifswald, Germay