X-ray conversion in preformed plasmas

Conference · Mon Nov 04 04:00:00 EST 1991

OSTI ID:6562244

Suter, L J; Kauffman, R L ^[1]; Cray, M ^[2]

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1. Lawrence Livermore National Lab., CA (United States)
2. Los Alamos National Lab., NM (United States)

The authors have carried out 1D and 2D calculational investigations which show that large, preformed plasmas can have higher x-ray conversion efficiencies than discs at the same irradiation intensity. In some situations, the x-ray conversion efficiency can approach 90%. Of the three common theoretical components of conversion efficiency (atomic physics, heat transport, power balance), they believe that changes to the power balance, due to changes in the hydrodynamics, is the mechanism by which preformed plasmas can have a higher conversion efficiency. They draw a more general conclusion from this work; in a world in which atomic physics and heat transport are [open quotes]fixed[close quotes], it may be possible to engineer conversion efficiency via changes that modify the power balance. The situation they model assumes a preformed plasma produced by a radiation pulse or a laser pulse. A 1ns preforming pulse, which in this work had a flux of [approximately]2.5[times]10[sup 14] w/cm[sup 2], strikes a gold target which may be either a sphere or a slab. The authors wait some delay time to allow plasma to evolve. Then they fire a 3ns, 3[omega] laser pulse into the preformed plasma. In this paper they discuss modelling results for three situations: a spherical preformed, spherically illuminated plasma; an infinite preformed plasma slab, infinitely illuminated; and an infinite preformed plasma slab illuminated with a finite size spot. The parameters of this study are delay time (which varies the scalelength of the preformed plasma) and laser intensity. The resulting plasmas for delay times of 3ns, 6ns and 10ns have scale lengths of [approximately]200[mu]m, [approximately]500[mu]m and [approximately]1mm, respectively.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6562244
• Report Number(s): UCRL-JC-107601; CONF-9110326--2; ON: DE93013347
• Country of Publication: United States
• Language: English

Related Subjects

664000* -- Atomic & Molecular Physics-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
CONVERSION
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
FLUID MECHANICS
GOLD
HYDRODYNAMICS
IONIZING RADIATIONS
IRRADIATION
LASER RADIATION
LASER TARGETS
LASER-PRODUCED PLASMA
MECHANICS
METALS
ONE-DIMENSIONAL CALCULATIONS
PLASMA
RADIATIONS
TARGETS
TRANSITION ELEMENTS
TWO-DIMENSIONAL CALCULATIONS
X RADIATION