MINIMIZING CHAOS DURING THE RECONNECTION PROCESS

Chaos around the separatrices of resonant chains during the reconnecti on process in Tokamaks with non-monotonic profiles is analysed. To cha racterize the extension of chaos in the system. we estimate the conver gence of the chaotic lines by computing the winding number profiles in the neighborhood of the separatrices. Same simulations were performed and we have detected, for these non-twist mappings, a reduction of ch aos during the reconnection process. A theoretical interpretation base d on the overlapping of resonance pictures is proposed in order to exp lain the decrease of chaos. These results may contribute to interpret the recently observed improvement in reversal magnetic shear in Tokama ks. (C) 1997 Elsevier Science Ltd.