Thermal Management Of Thin Film Electrode Repetitive Electro-optic Switches

High average power laser can enhance the interaction between light and material. It has broad application in the fields of high energy and high density physics, particle acceleration and laser fusion energy. More and more countries in the world pay attentions to the laser fusion energy. High repetition frequency laser technology developed rapidly, such as mercury device in the United States, Polaris device in the Germany, Lucia in France and Chinese SG facility. These laser driving devices have the characteristics of large diameter, high power, high frequency operation, and multi-pass amplification. The light pulse may heat the DKDP crystal. DKDP crystal has double refraction characteristics, which is very sensitive to thermal depolarization. High power frequency operation means that Pockels cell requires efficient thermal management. Pockels cell's thermal-control needs to be studied on farther.In the IFE laser system, Pockels cell operating under the condition of low flux. So that, transparent conductive films (TCO) can be used as electrodes. At the same time, the thin crystal was scaled to large aperture. The TCO electrode Pockels cell has two fluid channels for thermal control.Two aspects are included of this paper:Firstly, the thermal-management solutions of fluid-cooled heat transfer. This paper establishes a fluid-solid coupling finite element model to analyze the fluid-cooled heat exchanger characteristics. Fluid flow conditions are simulated to analyze the relevant factors of heat transfer coefficient and heat factors crystals deposited. At last, we obtain the structure parameters of Pockels cell. When the Pockels cell operates under the condition of 0.4J/cm2@16Hz, crystal's thermal effects was simulated in the optimized thermal management premise. The results from simulation indicated that:maximum temperature rise in the crystal is 1.5K, the maximum stress is 1.87 MPa, the maximum value of the stress birefringence depolarization loss occurs at the boundary of the spot, it was 0.38%; the total wave front distortion is 0.239?. Secondly, the thermal-management solutions of conduction heat transfer. We proposed a simplified structure of Pockels cell. This type of Pockels cell combines conductive heat management and fluid-cooled thermal management. The relevant structural parameters were obtained by theoretical analysis. The conductive heat-transfer characteristics were analyzed by experiment. When the average power of the incident laser is HOW, the maximum temperature, maximum depolarization loss and wave-distortion of the crystal was measured. The experimental results were compared with the numerical simulation results verify the validity of written procedures. Finally, we propose a management method:active heating Boundary Compensation. The average depolarized loss was significantly reduced by uniform the temperature gradient. This method can effectively increase the efficiency of thermal management. Therefore, the thin-film electrode Pockels cell is one of the ideal choices of high power pulse repetition frequency electro-optical switches.