Dynamics of current sheet formation and reconnection in two-dimensional coronal loops

Current sheet formation and magnetic reconnection in a two-dimensional coronal loop with an X-type neutral line are simulated numerically using compressible, resistive magnetohydrodynamic equations. Numerical results in the linear and nonlinear regimes are shown to be in good agreement with a recent analytical theory [X. Wang and A. Bhattacharjee, Astrophys. J. 420, 415 (1994)]. The topological constraint imposed by helicity-conserving reconnection is discussed. It is found numerically that helicity-conserving reconnection causes the initial X-point structure of the loop to change to Y points, with current sheets at the separatrices encompassing the Y points. Implications for observations are discussed.