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

Laser damage performance of optical components is a defect related material characteristic. Recent advances were made to realize repeatable and accurate measurements of surface density of damage initiation due to pulses of nanosecond duration. This new measurement technique was used to guide the improvement of surface damage resistance. Fractures must be eliminated from surfaces, in order not to suffer a damage growth phenomenon, whose exponential character will endanger the optical component. A dedicated set-up was mounted on ALISě laser. With it, laser damage growth was measured accurately, as well as its dependence on parameters like pulse length and pulse shape. Using data from LIL, a prototype of Laser Megajoule (LMJ), and from a specific set-up, we can estimate the effect of multi wavelength illumination on damage growth. High intensity hot spots due to beam modulations can also cause surface damage. New measurements of self-focusing were obtained. The predictions derived from this laboratory work were cross checked with LIL data. They are also useful to predict damage events during the operation of a large laser facility.