Research On Frequency Domain Characteristics And Noise Characteristics Of Magnetohydrodynamics Angular Rate Sensor

At present,magnetohydrodynamics(MHD)angular rate sensor(ARS)is one of the most reliable equipment for in-orbit measurements of micro-angular vibrations,by virtue of the compatibility with ultra-board bandwidth and ultra-low noise.However,existing measuring systems on frequency domain characteristics and noise characteristics of the MHD ARS still have certain defects and shortcomings.Thus,the relative researches need to be furtherly improved.In this thesis,researches from the aspects of theoretical analysis and experimental verification were conducted in the following sequences:First,based on the knowledge of magnetohydrodynamics,an analytical model of the MHD ARS was rebuilt,by analyzing the coupling procedure of three physical fields-Electric-Magnetic-Flow.Then an experimental device was designed for testing the transfer function of the sensor,by using a laser interferometer to calibrate the angular rate of the rotary table.Furthermore,the accuracy of the model was confirmed by comparing our results from experiments and numerical simulations.Second,by analyzing the noise source of the MHD ARS,the order of magnitude of the noise-floor level was theoretically evaluated.Then,the noise power spectral density was adopted to characterize the level,and features of some typical random noise of MHD ARS were analyzed.The work laid the theoretical foundation of noise analysis and evaluation of the MHD ARS.Finally,in order to measure sub-nV/(?)noise signals via the MHD ARS,a novel system was designed.By using the noise-matching transformer,this system combined the dual-channel cross-spectrum measurement method with the noise-matching principle.As a result,the noise figure during the measurement was optimized,accompanied by channel noise and coupled noise being effectively suppressed.In this system,the inherent noise was calculated through analytical models and circuit simulations,and the equivalent input voltage noise spectral density was reduced to the level of 0.1 nV/(?)which had been confirmed by our experiments.Then to take a step further,the proposed method even made it possible to measure an ultra-weak noise signal of the MHD ARS,which was as low as 0.06 nV/(?)Moreover,based on theoretical calculations,the dependence of root-mean-square of the thermal noise of the internal resistance in the MHD ARS on the ambient temperature was experimentally revealed.