Synergies Between Nuclear Fusion, Astrophysical and Industrial Plasmas: Prospective Challenges

Abstract: Simulated annealing (SA) is a kind of relaxation method,

where we solve an initial-value problem derived for a Hamiltonian sys-

tem so that the energy of the system changes monotonically while the

Casimir invariants are preserved. We have applied SA for reduced MHD

systems, where the energy is decreased by SA. Recently, it was shown

that SA can be used for stability analyses since it tries to find a lower

energy state. We found that spectral analysis of linearized SA equation

shows instability for a cylindrically symmetric equilibrium with sheared

poloidal rotation, where spectral analysis of linearized low-beta reduced

MHD itself does not show instability. This indicates that a perturbed

state has a lower energy, and that a negative energy mode exists. In

the talk, the linear spectral analysis as well as the SA results including

recent progress will be presented. Another analysis of a system with

magneto-rotational instability (MRI) will also be included.