流体静高压原位磁测量的误差研究（二）──退磁场的影响

 为了探讨流体静高压原位磁测量中退磁场的影响有多大？分别选用6种不同片数（n＝1、3、5、7、10、13）的非晶Fe_46.3Co_0.03Ni_46.5Si_3.75V_0.92B_2.5合金薄带样品，先后放进13层密绕直螺线管初级线圈内，采用工业频率400 Hz去测量和比较其磁化曲线、磁导率曲线和起始磁化曲线。研究表明：（1）样品片数越多，退磁场的影响越大，导致μ_m和μ_i出现惊人的测量误差，以1片（μ_m＝4 430，μ_i＝3 396）为最准。（2）随着样品片数的增多，测量饱和磁感应强度B_s＝0.837～0.762T，表明受退磁场影响较小。（3）若要减小退磁场误差，可将样品做得更薄，如0.2 μm薄膜。（4）若要彻底消除退磁场误差，必须采用闭合磁路，如用非晶合金薄带卷成的圆环。

A DISCUSSION ON THE ERRORS FOR THE IN SITU MAGNETIC MEASUREMENTS IN HYDROSTATIC HIGH PRESSURE VESSEL

To study the influence of demagnetic field in the hydrostatic high pressure vessel, we selected 6 samples with different slice-number (n=1, 3, 5, 7, 10, 13) of amorphous alloy Fe_46.3Co_0.03Ni_46.5Si_3.75V_0.92B_2.5 ribbon, inserted them into multiple electric solenoid and measured the magnetization, magnetic permeability and initial magnetization, respectively, at 400 Hz. We found that: (1) The more the slices of sample, the stronger the influence of demagnetic field was, which leaded in surprising errors of μ_m and μ_i. For the sample with 1 slice, we obtained the optimal values, μ_m=4 430, μ_i=3 396. (2) With the increase of slice number (n=1~13), we measured saturation magnetic induction B_s=0.837～0.762T, indicating the influence of demagnetic field on B_s was much small. (3) To reduce the error from demagnetic field, thinner sample could be used, for example thin film with 0.2 μm thick. (4) To eliminate the error from demagnetic field, closed magnetic circuit must be adopted, such as ring rolled up by amorphous alloy ribbon.