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This paper aims to comprehensively analyze the Alfven instability observed in the high βN discharge of EAST, considering both experimental observations and simulation studies. There are two purposes of this paper, the first one is to observe the AE activity in EAST, the second one is to apply and validate the FAR3d code in EAST. In the experimental analysis, the presence of a strong instability is detected using magnetic probes and electron cyclotron emission diagnostics. Two kinds of modes are observed:one's frequency ranging from approximately 70 kHz to 100 kHz, exhibiting an upward frequency sweep, and another frequency at around 60 kHz. These instabilities are found to destabilized near ρ=0.46 with a toroidal mode number of 2 calculated by toroidal Mirnov probe array. Complementing the experimental findings, simulations were performed using the eigensolver method of the FAR3d code. This is the first time that FAR3d code was applied on EAST, so the model needed to be validated by reproducing the AE activity. The simulation results successfully identify the dominant mode, toroidal Alfven eigenmode (TAE), occurring at ρ=0.45 with a frequency of 87 kHz, toroidal and poloidal number n/m=2/3, 2/4. Additionally, a sub-dominant mode, energetic particle mode (EPM), is identified at ρ=0.55 with a frequency of 62 kHz, n/m=2/4. The agreement between the simulation and experimental results confirms the accuracy of the simulation model in characterizing the instability types, as well as providing consistent location and frequency information. Furthermore, the FAR3d code is employed to evaluate the influence of the finite Larmor radius (FLR) effect. The simulation results demonstrate that the FLR effect has minimal impact on identifying low toroidal mode number (n) instability modes in the high βN discharge of EAST. Consequently, the FLR effect can be neglected during the mode identification process, allowing for accelerated calculations. While, in the simulation of high toroidal mode number, the FLR effects should be considered. In conclusion, this study presents a comprehensive analysis of the Alfven instability in the high βN discharge of EAST. By combining experimental observations with simulation results, the types of instabilities, their locations, and frequencies are successfully identified and found to be in good agreement. Additionally, the study confirms that the FLR effect has little influence on identifying low n instability modes, enabling faster calculations by excluding FLR effects during mode identification. These findings contribute to a better understanding of the Alfven instability in high βN discharges and provide valuable insights for future research in fusion plasma physics.

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