Multiple-line thermal blooming, strong t/sup 3/-blooming, and phase compensation calculations with FOUR-D

Conference · Sat Mar 01 04:00:00 EST 1980

OSTI ID:5585295

Morris, J R; Fleck, Jr, J A

FOUR-D's steady-state multiple-line mode was used to evaluate a power-weighted-average model of NACL beam propagation. Five NACL lines were propagated with separate intensity, phase, wavelength, and absorption coefficient. The on-target areas obtained from a power-weighted average model were up to 36% smaller than the corresponding multiple-line model areas. The maximum difference occurred for pure diffraction and decreased as thermal blooming was increased. The FOUR-D strong t/sup 3/-blooming model combines an exact solution of the linearized hydrodynamic equations with a steady-state model of overlap blooming. Propagation of a focused high-power multipulse laser beam with a uniformity illuminated square aperture demonstrates the generality of this model. In the examples, the square beam outperformed the Gaussian beam by 20 to 40% in peak intensity, 55 to 80% in half-power area. The contribution of t/sup 3/-blooming to the on-target area was decreased by overlap blooming for the Gaussian beam, but increased for the square beam. Two of FOUR-D's three models of phase compensation for steady-state thermal blooming - an effective thin lens and return wave - will also be discussed.

• Research Organization: California Univ., Livermore (USA). Lawrence Livermore Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5585295
• Report Number(s): UCRL-84021; CONF-800338-1
• Country of Publication: United States
• Language: English

Related Subjects

654001* -- Radiation & Shielding Physics-- Radiation Physics
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ABSORPTION
BEAM TRANSPORT
COHERENT SCATTERING
COMPUTER CODES
DIFFRACTION
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
F CODES
LASER RADIATION
MATHEMATICAL MODELS
RADIATIONS
SCATTERING