## 4 Experimental Results  
As outlined in the Section 3.1, the C-MHD ARS is designed and assembled to make an experiment that is comparable with the simulation results. In this work, we sought to provide the frequency response of a MHD ARS combing with the Coriolis effect at low frequency. The sensor is an open-loop system and works in a wide band, so the sweep-frequency test on a rotating table was adopted as the simple MHD ARS. In particular, a current supply connected to the energized electrodes is needed to drive the MHD pump in the C-MHD ARS. A large current should be provided by the current supply, although the power requirement is relatively low for extremely small impedance of the fluid in MHD pump. As discussed above, the current set for compensating could not be acquired in advance and needs to be tested again and again according to the experimental results at low frequency. Besides, the amplifying circuit is redesigned to improve the low-frequency noise suppression for the bandwidth extension at low frequency and still needs a voltage source to supply power. The magnification is set to 10,000. The data acquisition card (DAQ) and data process are adapted to collect the signal of the C-MHD ARS and the applied vibration by the rotating table. The sketch and physical map of the sweep-frequency experiment are presented in Figure 13.  
In the beginning, the frequency response of the sensor without the energized current is established and the results are plotted in Figure 14. The fixed phase deviation of about 10\({}^{\circ}\) is caused by the phase difference of the amplifier circuit. The corner frequency in the experiment is about 0.5 Hz, which is consistent with the one in the simulation presented in Figure 12. Besides, the amplitude after amplified is also in good agreement with the simulation results. Our results provide compelling evidence that the simulation method and the modified analytic model can be applied in the MHD ARS study. Then, the energized current is set to 3 A according to the numerical simulation. The experimental results of the frequency response at \(I=3\) A are illustrated in Figure 14. It seems that the frequency  
Figure 13: Frequency response experiment designed for C-MHD ARS. (**a**) Sketch Map (**b**) Physical map.  
response at low frequency has been improved but is far from the ideal. Unfortunately, the increase of amplitude and the reduction of phase difference are both relatively insufficient. The deviation of the frequency response in the experiment from the simulation results may be attributed to the weakened magnetic field intensity in the MHD pump and the viscous force and friction of the fluid channel in practice.  
In the next experiment, the energized current is increased slowly until the value is set to 6 A. As displayed in Figure 14, the amplitude and phase at \(f=0.01\) Hz are a little smaller than the one at \(f=0.01\) Hz. A similar trend can be observed in the range from 0.01 Hz to 10 Hz compared with the simulation results in Figure 12. The amplitude increases from 0.01 Hz to 0.5 Hz and then decreases to the value without an energized current until 2 Hz. As displayed, the amplitude at about \(f=0.5\) Hz reaches the peak, which is larger than the ratio above 1 Hz. Meanwhile, the phase fluctuation appears to mainly range from 0.1 Hz to 10 Hz. As shown, the phase gradually rises to deviate from the ideal value, then gradually falls below the ideal value and finally returns to the ideal value. The phenomena strongly confirmed that the error in the combination with the Coriolis and MHD effect exists, as illustrated in Section 3.4. It is difficult to acquire the ideal frequency characteristic curve directly by applying a fixed energized current in the MHD pump. The compensation method needs to be further studied. Furthermore, the energized current needed in the C-MHD ARS in this paper is less than perfect for the high density and dynamic viscosity of Galinstan. The design should be updated until the energized current is allowable.