Description
Toroidal rotation effects in the ideal magnetohydrodynamic (MHD) are well established and are treated here in a manner fully consistent with their implementation in linear ideal MHD code NOVA. The full MHD system proposed in Ref.[1] is generalized to the rotation modified system of equations structured in the same way. One particular application considered in details is the ideal MHD Alfvén continuum (AC) through second-order derivative terms that enter self-consistently via the rotating plasma equilibrium. Accurate treatment of these effects is essential for reliable simulation and interpretation of Alfvén eigenmode (AE) stability in present-day fusion devices. To analyze the AC, we adopt the rigorous approach developed by Cheng and Chance [1], which does not rely on small-parameter expansions but instead employs a Lagrangian formalism. This framework, further elaborated by Chu et al. [2], is applied here to rotating equilibria, and its implications for modeling the Alfvén continuum and AE stability are discussed. Our approaches allow to consider the slow mode approximation [2] or full MHD continuua as well as to compare it with the existing in the literature formulation in tokamak approximation with small value of the rotation [3].
[1] C. Z. Cheng and M. S. Chance, Phys. Fluids 29, 3695 (1986).
[2] M. S. Chu, J. M. Greene, L. L. Lao et al., Phys. Fluids B 4, 3713 (1992).
[3] B. van der Holst, A.J. C. Belien, J.P. Goedbloed, Phys. Plasmas, Vol. 7, No. 10, October 2000.