Theoretical analysis of the magnetic reconnection experiment, MRX
- Princeton Plasma Physics Lab., NJ (United States)
In the MRX experiment two identical spheromaks with a common major axis are driven together. Their poloidal fields are oriented so that at the point of contact reconnection occurs. Their toroidal fields are oriented either parallel or antiparallel. The general theoretical picture of the physics of the experiment is discussed. It is believed that an axisymmetric current layer forms between the two spheromaks, in which the reconnection occurs. In this layer the electron temperature is high due to ohmic heating, and there is considerable magnetic tension due to the merging poloidal field. In addition, in the counterhelicity case, there is magnetic tension in the toroidal direction. As a result of these forces large velocities develop in the layer. These velocities take the plasma out of the reconnection region, and into a thin separatrix region that lies, between the regions of unreconnected flux and common flux. In this separatrix region the motion quickly develops into heat. We first describe the experiment from a global point of view. At any time the plasma is in magnetostatic equilibrium everywhere except in the reconnection and separatrix regions. Across these regions the sum of magnetic pressure and the gas pressure is continuous. The high pressure in the region of common flux results from the dissipation of kinetic energy, and can be found by energy conservation since it really comes from dissipation of poloidal and, in the counterhelicity case, toroidal field energy. Thus, from the global point of view a unique sequence of equilibria is given. Once the global situation is determined the proper boundary conditions and geometry are available to treat the local behavior in the reconnection region by asymptotic analysis. The rate of reconnection determines the rate of passage through the sequence of equilibria. We attempt to carry out the inner analysis for a variety of reconnection rates ranging from the Sweet-Parker rate to the Petschek maximum reconnection rate.
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 489369
- Report Number(s):
- CONF-960354-; TRN: 97:011510
- Resource Relation:
- Conference: International Sherwood fusion theory conference, Philadelphia, PA (United States), 18-20 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 international Sherwood fusion theory conference; PB: 244 p.
- Country of Publication:
- United States
- Language:
- English
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