Abstract Details
Thermal ionization of an aluminum surface pulsed with MG magnetic field
Author: Thomas J. Awe
Requested Type: Poster Only
Submitted: 2009-04-17 17:58:03
Co-authors: B.S. Bauer, R.E. Siemon, S. Fuelling, V. Makhin
Contact Info:
University of Nevada, Reno
217 Bret Harte Avenue
Reno, NV 89509
USA
Abstract Text:
Whether vapor, warm dense matter, or plasma forms from a metal surface driven to high energy density by pulsed, multi-megagauss magnetic field is an important question for both basic science and for applications. Experimental data have not been available, and the complex interplay of magnetic diffusion, hydrodynamics, and radiative energy transfer is a challenge to model, especially because the material properties vary rapidly in space and time. We report in this work observations of thermal plasma formation on the surface of thick aluminum —where the magnetic skin depth is much less than the thickness of the conductor — in experiments at the University of Nevada, Reno. Surfaces are pulsed to high energy density by the 1-MA, 100-ns rise time Zebra generator. Thick aluminum rods with initial diameter ranging from 0.5 to 2.0 mm are pulsed to peak fields ranging from 1.5 to 5 MG. Plasma forms on the rod surface when magnetic fields reach approximately 2 MG. Measurements are made to infer the surface magnetic field, time of plasma formation, surface temperature, spectrum of emitted radiation, uniformity of surface heating and expansion, and growth rate of instabilities. Experiments have been designed to avoid non-MHD effects, and data have been compared with a number of radiation-MHD computation models.
* Work supported by DOE grants DE-FG02-04ER54752, DEFG02-06ER54892, DEFC52-
01NV14050, and DE-FC52-06NA27616
Comments:
Siemon will present paper; first author is Awe, who cannot attend meeting.