Fluctuations In Solar Coronal Heating Mechanism

As one of the major problems in solar-terrestrial physics, coronal heating has kept to attract physicists' attention for a few decades. In this thesis, we investigate the role of Alfven wave in the coronal heating process. All the work consists of two main parts. In the first part, turbulent motion in convection zone as source to generate Alfven waves is studied following Lighthill-Stein theory, in which the turbulent source was described by nonlinear terms in MHD equations. Using the technique of Fourier transformation, we can derive the Alfven wave energy spectrum generated from convection turbulence modeled with Kolmogroff-like power spectrum. Then, torsional Alfven waves propagate upwards along the coronal loop and the carried wave energy can make a play in coronal heating.The second part of our work is devoted to the dissipation mechanism of Alfven wave in coronal loop. On the basis of the linear theory of resonant absorption, nonlinear effect is taken into account in the wave dynamics. With a three wave interaction model, the pump wave mode is found to be strongly modulated by the background fluctuation, accumulated due to Alfven resonance near the resonant layer. And consequently, the phase modulation dissipation arises from the strong phase mixing between the waves inside and outside the modulation layer, and the pump wave is strongly damped near the resonant layer of coronal loop.After above analytical theories, we combine the two part of work into an integrated model of coronal heating. Evaluation results show that the turbulence in convection zone is capable of generating enough wave energy to supply coronal energy lose due to convection and radiation. Then, the obtained energy spectrum of the generated torsional Alfven wave is considered as boundary condition of coronal loop to calculate the subsequent wave dissipation. More interestingly, the derived damping length scales of the pump wave are consistent with the constraints proposed recently from the observation of localized heating of coronal loops.The papers related to this thesis were submitted and published in the central scientific journals, such as A&A and ApJ, and were highly evaluated by researchers overseas.