Design & simulation of high temperature blackbody source for calibration of Michelson interferometer ECE diagnostic

Abstract

This paper presents the design, simulation and characterization of a high temperature black body source for a target temperature of 873 K and frequency range of 70 to 143 GHz. The high temperature black body source has been designed using CST Microwave Studio. Different solvers in CST have been used to determine various black body parameters such as scattering, emissivity, reflectivity, radiation intensity, temperature distribution etc. This work consists of two novel approaches. First, the emissivity values have been calculated from the simulation results. Second, the design and optimization of the emitter and heater surface has been carried out separately and finally integrated to form the black body source. After sufficient study & literature survey, silicon carbide was selected as a suitable material for emitter and molybdenum for heater. The design comprises of a pyramidal moth eye structure made up of silicon carbide. Design and simulations were carried out with different dimensions of pyramids by varying their slant angle and height. The thickness of the silicon carbide base plate has also been varied to achieve optimal performance. Selection of best design is done by comparing results of radiation intensity, emissivity and temperature gradient of various simulated models. The design aimed to obtain the emissivity values near to unity with uniform temperature distribution across the emitter surface. Significant improvement in emissivity values were obtained by multiple changes in the heater and emitter design. The designed source after fabrication will be used as a high temperature calibration source for Michelson interferometer system serving as an electron cyclotron emission (ECE) diagnostic at IPR.