阿尔文波广泛地存在于太阳大气和太阳风中，被认为是日冕加热和太阳风加速的主要能量源。阿尔文波非线性不稳定性在太阳大气和太阳风中阿尔文波传播时的演化上具有重要作用。当阿尔文波垂直尺度减小时，其一维或二维非线性不稳定性转变为三维非线性不稳定性。目前已较清楚地揭示出阿尔文波一维和二维非线性不稳定性性质，但是尚未给出三维非线性不稳定性的完整图像。本项目将通过分析太阳大气和太阳风条件下的阿尔文波和慢波耦合系统中的三维非线性不稳定性、阿尔文波和快波耦合系统中的三维非线性不稳定性、以及阿尔文波一般非线性方程中的三维非线性不稳定性，给出阿尔文波三维非线性不稳定性的一般图像，揭示太阳大气中阿尔文波非线性阻尼机制，解释太阳风中快波和慢波观测、以及多尺度阿尔文波分布观测现象背后的非线性物理过程。本项目将为理解太阳大气和太阳风中与阿尔文波相关的多尺度和多模式波动现象中的物理机制提供基本理论基础。

Alfven waves are permeating the solar atmosphere and solar wind, being thought of as the major energy source of coronal heating and solar wind acceleration. The nonlinear instability of Alfven waves plays an important role in the propagation of these waves in the solar atmosphere and solar wind. When the perpendicular scale of the Alfven wave decreases, the one- or two-dimensional nonlinear instability of the Alfven wave becomes the three-dimensional instability in nature. Although it has been clearly explored the properties of the one- and two-dimensional nonlinear instability of the Alfven wave, there is no study giving the comprehensive picture for the three-dimensional nonlinear instability. This project will study the three-dimensional nonlinear instability of the Alfven wave in the nonlinear system between Alfven wave and slow/fast wave or in the general nonlinear equation of the Alfven wave under typical plasma parameters in the solar atmosphere and solar wind, exhibit the general picture of the three-dimensional nonlinear instability of the Alfven wave, explore the nonlinear damping mechanism of the Alfven wave in the solar atmosphere, explain the nonlinear physical processes associated with the observations of the fast/slow wave and multi-scale Alfven waves in the solar wind. This project will provide the fundamental theories for the understanding the physical mechanisms in the phenomena of multi-scale and multi-mode fluctuations relating to Alfven waves in the solar atmosphere and solar wind.