Three Component Effects on Driven Magnetic Reconnection in TS-3
Abstract
Mechanisms for externally driven magnetic reconnection have been investigated by use of two merging plasma toroids. Reconnection rate tends to increase with decreasing the magnetic field component BX parallel to the ``X-point'' line. In small BX reconnection(BX ~ the reconnecting field component B_//) case, the effective resistivity η of the current sheet was observed to increase rapidly (up to about 10 times as large as the classical resistivity), when the sheet width is compressed shorter than the ion gyroradius. Doppler width measurement of H_β line indicates the significant increase in the ion temperature(from 10eV to 100eV) right after the reconnection. In large BX reconnection(BX ~ 3B_//) case, the anomalous increase in resistivity nor strong ion heating were no longer observed, and the current sheet stays thicker than the ion gyroradius. Recent Mach probe measurement shows that the ion outflow velocity from X-point is as high as 70% of the Alfven speed of the upstream region( ~ 100km/sec). This outflow velocity explains quantitatively the high ion temperature after reconnection. The outflow velocity was also found to decrease with increasing B_X, in agreement with the dependence of the ion heating on B_X. The selective ion heating is probably caused by the themalization of accelerated ions though some bulk heating mechanisms such as large ion viscosity around X-point.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- November 1997
- Bibcode:
- 1997APS..DPPdMP112I