Tham khảo tài liệu 'two phase flow phase change and numerical modeling part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Thermal Approaches to Interpret Laser Damage Experiments 229 that the laser damage density globally decreases in the range 0 90 . If considering now the black arrows these points correspond to local generation of SHG. It has been noticed that for these particular points . Q 40 and Q 60 the laser damage density is punctually altered as an indication that SHG tends to cooperate to damage initiation. Experiments 10 10 1 r 10 F 19 0 J cm2 to F 24 5 J cm2 to F 19 0 J cm2 to - - Ffa 24 5 J m Model 0 10 20 30 40 50 60 70 80 90 Rotation angle ÍÌ Fig. 6. Evolution of laser damage density as a function of Q for two different 1w fluences. Green triangles and orange squares respectively correspond to F1v 19 J cm2 and F1v J cm2. Modeling results are represented in dash lines respectively for each fluence. Modeling results are discussed in Sec. . Many assumptions may be done to explain these observations. Crystal inhomogeneity tests repeatability self-focusing walk-off and SHG Demos et al. 2003 Lamaignère et al. 2009 Zaitseva et al. 1999 were suspected to be possible causes for these results due to their orientation dependence they may induce. But it has been ensured that these mechanisms were not the main contributors even existing participating or not to explain the influence of polarization on KDP laser damage resistance. This assessment has to be nuanced in the case of SHG. These conclusions are also in agreement with literature relative to non -linear effects in crystals qualitatively considering the same range of operating conditions ns pulses beams of few hundreds of microns in size intensity level below a hundred GW cm2 etc . To conclude on the experimental part it is thus necessary to find another explanation than SHG . This is addressed in the next section which introduces defects geometry dependence and proposes a modeling of the damage density versus fluence and Q. Modeling coupling DMT and DDscat models DMT model The DMT code presented in Sec.
