Laser damage phenomena relevant to the design and operation of an ICF laser driver

Damage growth in fused silica optics at 351 nm: refined modeling of large-beam experiments

“…Bold squares are very close to this line, meaning that the growth behavior can be described in average by a unique value at a given fluence. A growth threshold around 5 J/cm 2 is deduced from this experiment; it corresponds to the threshold previously reported by several authors [4][5][6][7][8][9][10][11][12][13][14][15][16]. Shot after shot, damage sites are bigger and bigger, but for a given laser energy deposition, the stresses developed by the pressure pulse remain equal for longer circumferential and radial cracks that are more numerous too.…”

“…In this figure, a change in the slope in this semilogarithmic representation is perceptible too (dashed areas are just a guide for eye), meaning that other parameters are involved in the description of the growth. It is commonly admitted that the rear growth phenomenon is well characterized by an exponential behavior [4][5][6][7] except for shorter pulse duration where a linear growth is sometimes observed [6]. On this basis, we consider the singleshot growth rate coefficient k defined in Eq.…”

“…On this basis, we consider the singleshot growth rate coefficient k defined in Eq. (1) [5]. Figure 5 reports the growth coefficients experimentally measured as a function of fluence during a series of six shots, for each individual damage site and after each shot.…”

“…Values of the coefficient C are reported in the insert for each size bin. The dashed line is the standard behavior from literature [4][5][6][7][8][9][10][11][12][13][14][15][16] Refined modeling of large-beam experiments 523…”

“…Then a sequence of N shots leads to an area increase in a factor e Nk [5]. Numerous experimental results obtained by Norton et al at Livermore are now available.…”