Thermal modeling and analysis of 193 nm pulsed excimer laser calorimeters

This work describes the thermal modeling and analysis of pulsed excimer laser calorimeters at a wavelength of 193 nm. Different thermal models have been developed and the finite element method is employed to perform the thermal modeling of the volume absorber and the cavity in the 193 nm laser calorimeter.; In this work, the heat generation rates in volume absorber and the heat flux on the copper surface have been derived and the finite element method is employed to simulate the space- and time-dependence of temperature in the absorber. A three-dimensional model and an axisymmetric model have been built and used to study the heating effects of single pulse and multiple pulses, respectively. The proposed design, in which the volume absorber is not optically thick, was analyzed under consideration of the reflection and absorption at the interface. The comparison of the present design to the proposed design shows that the accuracy and dynamic range can be improved for the volume absorber with low absorption coefficient. The two-photon absorption in the volume-absorbing glass is investigated and the results show that the two-photon absorption can compress the volume-absorbing effect to surface absorption with high-power, short-pulse laser irradiation.; The parametric study of excimer laser calorimeter has been performed for pulsed-laser heating, average-power laser heating, and electrical heating using the axisymmetric model in which the volume absorber with small thickness and high absorption coefficient was considered. The maximum temperature is higher for pulsed-laser heating than for electrical heating when the amount of total deposited energy is the same. The equivalence between pulsed-laser heating and average-power laser heating is verified through the axisymmetric modeling of the cavity. A three-dimensional model of the full cavity is employed to predict the calibration factor for laser heating. The nonequivalence of the laser calorimeter is evaluated based on the results of the full cavity modeling. Detailed thermal modeling and analysis of laser calorimeter are provided which help understand the thermal response of the volume absorber and the cavity under laser heating and electrical heating. This work will help improve the future design of pulsed-laser calorimeters.