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Assuming the observed scaling of laser damage threshold fluence with the (almost) square root of pulse duration is due to thermal conduction, we develop a formalism for directly comparing pulses of different shapes and durations. We find, for example, that a top hat pulse leads to 15% higher temperature (presumably 15% lower damage threshold) than a Gaussian pulse of the same fluence. We also find that the damage threshold of the expected NIF type pulse should be estimated from a Gaussian pulse with the same peak intensity. We find that the deviation of the scaling of damage threshold from square root of pulse duration has contributions from both the small but finite size of laser energy absorbers and from the temperature dependence of thermal properties. Keywords: laser damage, damage threshold, scaling, thermal conduction
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