Theoretical analysis on thermal management of Ti:sapphire-based petawatt laser systems with a high repetition rate

High-repetition-rate, ultra-intense ultrafast lasers are essential for advancing scientific research. However, thermal effects pose challenges for high repetition rate operation. This study provides a theoretical analysis of the thermal effects in the main amplifiers of a high-repetition-rate, petawatt-class TI: sapphire laser system. We begin by evaluating the gain performance to determine the optimal pump energy, which directly influences heat deposition within the amplifiers. The amplifier design uses 100 mm diameter TI: sapphire crystals with a total thickness of over 40 mm and a pump energy exceeding 110 J, based on experimental data from existing systems. The active-mirror configuration is a promising solution for high-repetition-rate TI: sapphire petawatt lasers. We evaluate various cooling conditions based on key thermal parameters, including temperature distribution, thermal stress, and thermally induced wavefront distortion. The results show that dividing the amplifier into seven laser heads, each with a 6 mm-thick TI: sapphire crystal mounted on a 20 mm-thick diamond heat sink, enables effective thermal management. At 80 K with a heat transfer coefficient of 4200 W/m²/K and 16 kW pump power (16 J per pulse), the laser heads can sustain 1 kHz operation. Our findings indicate that the active-mirror configuration offers superior heat dissipation, making it a promising solution for kilohertz-level petawatt laser systems.