A 3.04 J, 200 Hz Diode-Side-Pumped Nd:YAG Nanosecond Laser System

A Nd:YAG nanosecond laser system delivering a single-pulse energy of 3.04 J at a repetition rate of 200 Hz has been developed for Thomson scattering diagnostics in fusion devices. The seed source uses a Cassegrain unstable cavity with a Gaussian variable-reflectivity mirror to generate a flat-top beam. The amplification stage comprises two-rod tandem side-pumped amplifier modules with a 90° quartz rotator between the rods in each module to compensate for thermally induced depolarization. The output pulse duration is 10.7 ns at 3.04 J and 200 Hz. The root mean square (RMS) pulse-to-pulse energy stability was 0.33% over 3200 consecutive shots. The output spectrum was centered at 1064.38 nm with a linewidth of 1.07 nm. The beam roundness and smoothness coefficient were 90.8% and 0.313, respectively. The design avoids optical components susceptible to damage and simplifies the system architecture. The system can serve as a high-repetition-rate, high-pulse-energy nanosecond laser source for Thomson scattering diagnostics.