In order to understand turbulent transport phenomena in magnetized plasmas, an excitation condition of the ion-temperature-gradient (ITG) instability is investigated in linear device PANTA. Numerical analyses using a global gyro-fluid code in linear devices are performed to obtain mode structures and parameter dependences of the ITG instability. Parameter scans of the linear growth rate show the destabilization condition of the ITG modes. The global analysis considers the boundary condition and determines the radial mode structure, which gives the values of the wavenumber in the direction perpendicular to the magnetic field. The local analysis confirms to reproduce the global analysis result by using the wavenumber obtained from the global analysis. The wavenumber is a parameter in the local model, and the global analysis of the radial mode structure is necessary for the selection of this important parameter.

Numerical analyses using a gyro-fluid model have been performed to investigate the finite-Larmor-radius (FLR) effect on ion-temperature-gradient (ITG) instability in cylindrical plasmas. A spectrum code with Fourier-Bessel expansion has been developed for the analysis of global mode structures. The analytical expression of the η (ratio between the density and temperature gradient lengths) threshold value for linear ITG instability has been obtained from the local dispersion relation, whose dependency on the ion temperature comes from the FLR effect. Dependency of the threshold by the global analysis is reproduced by the local analysis with appropriate selection of the perpendicular wavenumber. Break of the Boltzmann relation by the FLR effect is not strong as to generate another unstable branch of the ITG mode.