SHEAR ALFVENIC DISTURBANCES IN THE VICINITY OF MAGNETIC NULL X-POINTS

The dynamics of shear Alfvenic disturbances in the vicinity of two-dim ensional magnetic null X-points is studied. The study complements rece nt work on compressional Alfvenic disturbances near X-points. For dist urbances not straddling the separatrix, it is found that the shear Alf ven wave phase mixes rapidly. The damping rate, however, is not as lar ge as [ln(1/eta)](-2), as was found for magnetosonic disturbances (eta is the resistivity). For low-frequency forced motions straddling the separatrix, sheet currents are formed at the separatrix and the curren t layer width is found to scale as eta(1/2). This results in a volumet ric ohmic heating rate which also scales as eta(1/2).