RLCYC 75: A 2 kW electrically calibrated laser calorimeter designed for Laser MegaJoule diagnostics calibration

Abstract

RLCYC 75 is a new electrically calibrated laser calorimeter specially manufactured by Laser Metrology to calibrate energy diagnostics within the Laser MegaJoule (LMJ) facility. It consists of an optical cavity cooled by a hydraulic system. The system is designed to provide 1 m wavelength power laser measurements with uncertainty less than 1% at 2 kW and traceability to the International System of Units (SI). In this paper, the accuracy of RLCYC 75 measurements is studied. More precisely, three points are detailed: instrumentation uncertainty estimation, equivalence between optical and electrical supply and light absorption. To this end, electrical calibration campaigns and power laser measurement campaigns are conducted. Moreover, thermal and optical models are developed. Results show that RLCYC 75 design and instrumentation are efficient enough to reach the goal of relative uncertainty of about 1% at 2 kW. RLCYC 75 will become the 2 kW laser power primary standard for LMJ applications