Feature Measurement System Of High-Temperature Superconductor

With the development of superconducting technology, its application field and scope has expanded. Now, its influence has spread to every aspect of people's daily lives.On the basis of correlation detection theory, this paper has given a new measurement program based on correlation detection, and has demonstrated the feasibility of this theory which is used in superconductor resistance measurement. This system's hardware design include: current source circuit, superconductor resistance measurement circuit and superconductor ambient temperature measurement circuit three parts. In the current source circuit, in order to produce 1KHz square-wave signal with smaller noise, this design uses a CD4060 chip (14-bit binary serial counter) to supply digital power, improving the accuracy of the current source; In the part of superconductor resistance measurement circuit, use high-performance DSP chips TMS320VC5509A to constitute lock-in amplifier, which making the correlated detection to be realized. TMS320VC5509A has 2-Channel 10-Bit A/D, using it can simplify the processing of design, minify the circuit frame. The design uses ATMEL's EEPROM AT25256 to reserve process for DSP, and uses MAX3111 to contact DSP and computer; In the part of superconductor ambient temperature measurement circuit, use double-integrating A / D ICL7135 to complete the conversion from analog signal to digital signal, then use AT89C2051 MCU to achieve the temperature conversion of thermocouple. In the interface design of AT89C2051 and ICL7135 using only two lines to connect, effective savings the MCU's I/O port resources, reduces the circuit's complexity. In software design, use C language and assembler language to program the DSP's initialization procedure, A/D sampling procedure, McBSP data transmission procedure and correlation detection procedure in the CCS environment. MCU's program design is in Keil uVision2 environment using C and assembler language to complete too, and has programmed the MCU's initialization procedure, the communication procedure with ICL7135, inventory procedure to get the superconducting ambient temperature, and so on. Experiments indicated that this measurement system can detect the weak superconductor resistance signals effectively, and it fully showed that the system has large advantage in the weak signal detection such as superconductor resistance measurement.