LAUSR

We develop from scratch a comprehensive linear stability eigenvalue code based on a finite element method, namely, the drift Alfven energetic particle stability (DAEPS) code, to investigate the physics of various stable and unstable modes observed in toroidal fusion plasmas, which has the advantage of accurate calculation of the mode characteristics near marginal stability. The DAEPS code is dedicated to providing a thorough understanding of low frequency modes in collisionless plasmas, e.g., shear Alfven wave SAW and drift Alfven wave physics with an energetic particle (EP) effect. DAEPS can calculate the linear frequency and growth rate for these modes by keeping correct asymptotic behavior in ballooning space. In this work, we demonstrate that the DAEPS code is able to analyze linear electromagnetic modes excited by circulating particles, including the thermal particle excited beta-induced Alfven eigenmode and EP excited toroidicity-induced Alfven eigenmode, where the verifications are performed successfully with other codes and theories, where the finite orbit width is discovered to play an important stabilizing role, which are usually ignored by traditional theory.