title: Ion viscous heating in a magnetohydrodynamically unstable Z pinch at over 2 x 10(9) Kelvin.
abstract: Pulsed power driven metallic wire-array Z pinches are the most powerful and efficient laboratory x-ray sources. Furthermore, under certain conditions the soft x-ray energy radiated in a 5 ns pulse at stagnation can exceed the estimated kinetic energy of the radial implosion phase by a factor of 3 to 4. A theoretical model is developed here to explain this, allowing the rapid conversion of magnetic energy to a very high ion temperature plasma through the generation of fine scale, fast-growing m = 0 interchange MHD instabilities at stagnation. These saturate nonlinearly and provide associated ion viscous heating. Next the ion energy is transferred by equipartition to the electrons and thus to soft x-ray radiation. Recent time-resolved iron spectra at Sandia confirm an ion temperature Ti of over 200 keV (2 x 10(9) degrees), as predicted by theory. These are believed to be record temperatures for a magnetically confined plasma.
authors.affiliation: Physics Department, Imperial College, London SW7 2BW, UK. m.haines@imperial.ac.uk
authors.forename: M G
authors.initials: MG
authors.lastname: Haines
authors.forename: P D
authors.initials: PD
authors.lastname: LePell
authors.forename: C A
authors.initials: CA
authors.lastname: Coverdale
authors.forename: B
authors.initials: B
authors.lastname: Jones
authors.forename: C
authors.initials: C
authors.lastname: Deeney
authors.forename: J P
authors.initials: JP
authors.lastname: Apruzese