The Madison plasma dynamo experiment: A facility for studying laboratory plasma astrophysics

• DOI: 10.1063/1.4861609
• Publication Date: 2014-01-16T17:58:31Z
• Authors: C. M. Cooper; J. Wallace; M. Brookhart; M. Clark; C. Collins; W. X. Ding; K. Flanagan; I. Khalzov; Y. Li; J. Milhone; M. Nornberg; P. Nonn; D. Weisberg; D. G. Whyte; E. Zweibel; C. B. Forest
• Keywords: Plasma Physics (physics.plasm-ph); 0103 physical sciences; FOS: Physical sciences; 7. Clean energy; 01 natural sciences; Physics - Plasma Physics

The Madison plasma dynamo experiment (MPDX) is a novel, versatile, basic plasma research device designed to investigate flow driven magnetohydrodynamic (MHD) instabilities and other high-$��$ phenomena with astrophysically relevant parameters. A 3 m diameter vacuum vessel is lined with 36 rings of alternately oriented 4000 G samarium cobalt magnets which create an axisymmetric multicusp that contains $\sim$14 m$^{3}$ of nearly magnetic field free plasma that is well confined and highly ionized $(>50\%)$. At present, 8 lanthanum hexaboride (LaB$_6$) cathodes and 10 molybdenum anodes are inserted into the vessel and biased up to 500 V, drawing 40 A each cathode, ionizing a low pressure Ar or He fill gas and heating it. Up to 100 kW of electron cyclotron heating (ECH) power is planned for additional electron heating. The LaB$_6$ cathodes are positioned in the magnetized edge to drive toroidal rotation through ${\bf J}\times{\bf B}$ torques that propagate into the unmagnetized core plasma. Dynamo studies on MPDX require a high magnetic Reynolds number $Rm > 1000$, and an adjustable fluid Reynolds number $10< Re <1000$, in the regime where the kinetic energy of the flow exceeds the magnetic energy ($M_A^2=($v$/$v$_A)^2 > 1$). Initial results from MPDX are presented along with a 0-dimensional power and particle balance model to predict the viscosity and resistivity to achieve dynamo action.<br/>14 pages, 13 figures<br/>