The effect of central plasma pressure on high-order harmonics of 1/1 quasi-interchange instability in central weak magnetic shear tokamak configuration

Numerical investigations of linear and nonlinear stages of quasi-interchange instability in a cylindrical tokamak geometry with a flat q-profile in the core region are conducted using eigenvalue and initial value codes, respectively. It is found that there exists a dependent relationship between the central plasma pressure (of initial pressure profile) and the dominant harmonic of the quasi-interchange instability. As increase, the dominant harmonic at linear stage is observed to become higher and eventually leads to a higher () dominant quasi-interchange instability at nonlinear stage (from 1/1 to 4/4 even 5/5 in our results), where m and n are the poloidal and toroidal mode number, respectively. In addition, with increasing, the fast growing of other harmonics are inevitable and will deeply affect the evolution of dominant quasi-interchange instability.