Abstract Electromagnet measurements of demagnetization M ( H ) curves of two Nd-Fe-B cylinder specimens of radius and length r s = l s = 5 mm with different length l g = l 0 - l s , l 0 being the pole gap length of electromagnet, of end gaps are carried out using a B-coil or a pair of J-coils to detect B or M and a Hall probe to record H. The measured curves for l g > 0 are demagnetizing corrected to be consistent with that for l g = 0 , after the volume and midplane averaged demagnetizing factors, N vol and N mid , are calculated as functions of γ s ≡ l s / ( 2 r s ) and l g / l s , using an effective solenoids approach. It is found that the measured intrinsic coercivity H ci for l g > 0 is always smaller than that for l g = 0 , N mid and l g / l 0 could be used as the demagnetizing factor for the correction with respect to M in the B-coil and J-coils cases, respectively, and p H l g / l 0 ( N vol ) , where p H decreases with decreasing l g , may be used as the demagnetizing factor for the correction with respect to H. The mechanisms of these phenomena are studied by further calculations on the local demagnetizing fields and on the magnetization reversal process based on a tubular reversal model.

中文翻译：

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具有端隙的 Nd-Fe-B 试样的电磁铁测量中的退磁效应

摘要 两个半径和长度为 rs = ls = 5 mm 的 Nd-Fe-B 圆柱试样的退磁 M ( H ) 曲线的电磁测量，不同长度 lg = l 0 - ls ， l 0 是电磁铁的极隙长度，端间隙使用 B 线圈或一对 J 线圈检测 B 或 M 和霍尔探头记录 H。 lg > 0 的测量曲线经过去磁校正，与 lg = 0 的曲线一致，在体积和中平面平均退磁因子 N vol 和 N mid 被计算为 γ s ≡ ls / ( 2 rs ) 和 lg / ls 的函数之后，使用有效的螺线管方法。发现 lg > 0 时测得的内禀矫顽力 H ci 总是小于 lg = 0 时的值，