Thermal response and inequivalence of pulsed ultraviolet-laser calorimeters

This work investigates the thermal response of calorimeters that are Used for measuring pulsed-laser energies at a wavelength of 193 nm, based on finite element models, and evaluates the inequivalence between laser heating and electrical heating. An axisymmetric model is built to study the thermal response of the cavity under both pulsed-laser heating and average-power (laser) heating. The small relative differences between pulsed-laser heating and average-power heating establish the feasibility of predicting calorimeter's thermal behavior for pulsed-laser heating by using the corresponding average-power heating. A three-dimensional finite element model of the entire cavity is developed and then used to predict the thermal response for average-power laser heating and electrical heating. The calibration factors (i.e., sensitivity factors) are obtained, and the inequivalence of the 193-nm laser calorimeter is calculated to be approximately 0.4%. The theoretical prediction provides a good reference for experimentally evaluating the inequivalence of the 193-nm pulsed-excimer-laser calorimeters.