Design and development of laser temperature control system of LHAASO

The Large High Altitude Air Shower Observatory (LHAASO) is located in Haizi Mountain, Daocheng County, Sichuan Province, with an average altitude of 4410 m. The Wide Field of view Cherenkov Telescope Array (WFCTA) is one of its three observation arrays. Laser calibration system for WFCTA consists of 2 nitrogen lasers and 1 Nd:YAG laser system. During the operation of WFCTA, the outdoor temperature may dropped from 17 & DEG;C to about -30 & DEG;C, which will bring serious challenges to the operation of laser calibration system operating in the field. In order to ensure the stable working environment and remote operation of the laser, we have developed the LHAASO-WFCTA laser temperature control, remote control and data monitoring system. The fluctuation of temperature in the box is within 1 & DEG;C around the target. The laser temperature control system was officially put into operation in Sept. 2020. In this paper, the design scheme, fabrication scheme, comparison of heat dissipation coefficient and test of temperature control system are introduced. The working data shows that both nitrogen molecule lasers and Nd:YAG laser temperature control system can achieve stable and long-term operation in high-altitude extreme field.