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Status of the Maryland Centrifugal Experiment (MCX)
| Author: | Ellis R. F. |
| Coauthor: | A. Case, R. Elton, J. Ghosh, H. Griem, A. B. Hassam, R. Lunsford, R. McLaren, S. Messer, C. Teodore |
| Institution : | University of Maryland |
| Abstract text: | MCX studies supersonically rotating plasmas produced by the application of a radial electric field perpendicular to an axial magnetic field. MCX has a magnetic mirror geometry of 2.6m length, variable mirror ratio (2-20), maximum mirror field of 1.9T, maximum midplane field of 0.5T. Biasing of an inner core relative to the outer wall produces a radial electric field which drives the azimuthal rotation. The capacity of the 10 KV capacitor bank for the discharge has been increased five fold and a freewheeling capability implemented. In standard mode MCX now achieves high density (n>1020 m-3) fully ionized plasmas rotating supersonically with azimuthal velocities in the range of 100 km/sec for discharge times exceeding 8 ms under a wide range of conditions. Ion temperatures are typically 30 eV and momentum confinement times exceed 100 microseconds. Sonic mach numbers are 1-2 and Alfven mach numbers somewhat less than 0.5 . MCX plasmas remain quasi-stable for many milliseconds, much longer than MHD instability timescales, though magnetic probes show substantial fluctuations; plasma lifetime appears to be limited only by the capacitor bank stored charge. Ion density, confinement time, and the voltage across the plasma increase with magnetic field strength; rotation velocity saturates at higher B and good performance requires mirror ratios of 5 or greater. The scaling of confinement time with magnetic field will be discussed. New diagnostics include diamagnetic loops and a variable chord Doppler spectrometer. Most recently, MCX has demonstrated an enhanced mode of operation with higher rotation velocities and confinement times, which is described in paper C. Teodorescu, et al at this workshop. Future plans for MCX will be described. |
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