A novel approach to global gyrokinetic simulation is implemented in the flux-tube code stella. This is done by using a subsidiary expansion of the gyrokinetic equation in the perpendicular scale length of the turbulence, originally derived by Parra and Barnes [Plasma Phys. Controlled Fusion, 57 054003, 2015], which allows the use of Fourier basis functions while enabling the effect of radial profile variation to be included in a perturbative way. Radial variation of the magnetic geometry is included by utilizing a global extension of the Grad-Shafranov equation and the Miller equilibrium equations which is obtained through Taylor expansion. Radial boundary conditions that employ multiple flux-tube simulations are also developed, serving as a more physically motivated replacement to the conventional Dirichlet radial boundary conditions that are used in global simulation. It is shown that these new boundary conditions eliminate much of the numerical artefacts generated near the radial boundary when expressing a non-periodic function using a spectral basis. We then benchmark the new approach both linearly and non-linearly using a number of standard test cases.

在通量管代码stella中实现了一种新的全局陀螺动力学模拟方法。这是通过在湍流的垂直尺度长度中使用陀螺动力学方程的辅助展开来完成的，最初由 Parra 和 Barnes [Plasma Phys. 受控融合，57054003, 2015]，它允许使用傅里叶基函数，同时能够以微扰方式包含径向轮廓变化的影响。通过利用 Grad-Shafranov 方程的全局扩展和通过泰勒展开获得的米勒平衡方程，包括磁几何的径向变化。还开发了采用多个通量管模拟的径向边界条件，作为全局模拟中使用的传统狄利克雷径向边界条件的更物理替代。结果表明，当使用谱基表达非周期函数时，这些新的边界条件消除了在径向边界附近产生的大部分数值伪影。