Studies and development of FBG based multi-point temperature sensor for vacuum chambers of synchrotron radiation source Indus-2

This paper presents the development and deployment of a multi-point fiber Bragg grating (FBG) sensor system for precise temperature monitoring along the vacuum chamber walls of dipole and Pinger magnets in Indus-2, a synchrotron radiation source. The challenging environment includes bremsstrahlung radiation (20 Rad/h), strong magnetic fields (1.5 T), and high RF fields (∼0.8 MV/m at 505.812 MHz). The sensor system was created by inscribing multiple FBGs at distinct wavelengths on a single optical fiber using the second harmonic of a copper vapor laser (CVL). The FBG array was validated for operation in high-radiation and high-voltage (∼10 kV) conditions. It was installed to monitor temperature profiles during Indus-2 operation at 2.5 GeV, 200 mA, where chamber temperatures ranged from 18 °C to 40 °C. The significance of this observation lies in its potential application for the early detection of electron beam orbit mis-steering occurrences, thereby facilitating real-time temperature monitoring and the subsequent optimization of electron beam orbit alignment. Such proactive measures are crucial for ensuring the dependable and consistent operation of Indus-2.