Design Of Transient Temperature Measurement System Based On Magnetic Nanoparticles

Transient temperature measurement is of great importance in the study of basic heat transfer law and laser-related or other transient thermal processes.Compared with other transient temperature measurement methods,the method based on superparamagnetic magnetic nanoparticles has the advantages of non-contact and can measure the internal temperature of objects.Under the effect of constant external magnetic field,there is a monotone correspondence between magnetization and temperature of magnetic nanoparticles.By measuring the variation of magnetic field around magnetic nanoparticles,the magnetization of magnetic nanoparticles can be computed,and then the temperature can be solved.Firstly,the principle of transient temperature measurement based on magnetic nanoparticles is studied in this thesis.A transient temperature measurement method based on the monotone correspondence between magnetization and temperature of magnetic nanoparticles is proposed.Influence of external excitation magnetic field on measurement sensitivity is studied.Temperature inversion error of the measured signal in different SNR is simulated.Then,a transient temperature measurement system is designed,which consists of a pulsed laser,excitation magnetic field,magnetic nanoparticle samples,low frequency and high frequency measurement circuit.According to the amplitude-frequency characteristic of coil transfer function in different frequency bands,coils and circuits are designed.Amplitude-frequency characteristic of the measuring circuits is tested.Finally,an experimental platform of transient temperature measurement based on magnetic nanoparticles is constructed.Thin-film thermocouples are designed to provide temperature reference for magnetic nanoparticles transient temperature measurement experiment.Experiment results show that the transient temperature measurement system designed in this thesis can measure temperature pulse with rising edge less than 2ns.After calibration of magnetic nanoparticles response,the relative error between the maximum temperature measured by magnetic nanoparticles and thin film thermocouple is less than ± 5%.In conclusion,it's feasible to use magnetic nanoparticles for transient temperature measurement.