A Study Of High Precision Programmable Current Source For Transition Edge Sensor Detector

The superconducting transition edge detector is one kind of the cryogenic detectors deployed in the Shanghai HIgh repetitio N rate XFEL and Extreme light facility(SHINE).It is a low temperature superconducting detector with extremely high sensitivity.Such detector has been widely used in the fields such as the detection of gravitational waves,observation of millimeter waves,and measurement of X-ray energy spectrum and dark matter et al.The main parts of superconducting transition edge detector are composted of Transition Edge Sensor(TES)and Superconducting Quantum Interference Device(SQUID).In order to obtain the normal working performance,an external power supply is necessary to provide bias current for both TES and SQUID.Owing to its high sensitivity accuracy and stability of cryogenic devices,it would be subject to the fluctuation of the bias current.Up to now,the conventional bias current is usually supplied by a combination of batteries in series with precision resistors,or by a programmable power in the labs.However,these approaches have several disadvantages such as poor flexibility,large size,weak communication capabilities,and instability.In this thesis,a programmable current source module is designed,according to the demand of TES and SQUID for bias current.The module can generate and scan weak signal ofμV/μA.The dimension of the entire module is less than 20 mm~2 and the accuracy of its voltage output can reach up to 0.1μA.It has been successfully applied for TES and SQUID,and also be applied to measure the DC characteristics of the DC-SQUID series array.In order to get better understanding of the DC characteristics of the DC-SQUID series array,a DC relationship equation is established,based on the RSJ model of Josephson junction.Then,the influence of Gaussian white noise on DC characteristics of the DC-SQUID series array is analyzed,by solving the equivalent Fokker-Planck equation.Moreover,the specific parameters of the DC-SQUID series array are accurately calculated.The current source module designed in this thesis has a strong scalability,which will play an important role in many fields,such as weak signal measurement,CNC,etc.This thesis comes up with a DC circuit diagram and I-V equation for DC-SQUID series array.The above results will provide a theoretical basis for the further testing and screening of DC-SQUID.