Global mode analysis of ion-temperature-gradient instabilities using the gyro-fluid model in linear devices

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.