Accession Number:

ADA037218

Title:

Steady State Thermal Blooming of Multipulse Laser Beams,

Descriptive Note:

Corporate Author:

DEFENCE RESEARCH ESTABLISHMENT VALCARTIER (QUEBEC)

Personal Author(s):

Report Date:

1977-02-01

Pagination or Media Count:

36.0

Abstract:

Steady state thermal blooming of multipulse laser beams subjected to cross winds is studied in the light of numerical solutions. Enhancement resulting in a 100 increase of the peak irradiance with respect to the non-bloomed but linearly absorbed beam is demonstrated at the optimal pulsing rate. The corresponding gain in terms of spatially averaged power density over the target area containing 85 of total power is 40. A parametric study is made as a function of three similarity parameters which are sufficient to completely define the problem the number kappa which is the reciprocal of the number of pulses per flow time, the Fresnel number F based on the absorption-irradiance interaction length scale and the absorption number gamma related to linear depletion. Optimal conditions for a collimated Gaussian beam are shown to exist for 0.8 approximately less than kappa approximately less than 1.0 and F approximately greater than 20. Intensification generally decreases with increasing gamma but only slightly. Author

Subject Categories:

  • Lasers and Masers
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE