Effect of primary coil size on eddy current decay resistivity measurements

✍ Scribed by K.T. Hartwig; C.Y. Hua; L.C. McDonald

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 592 KB
• Volume: 31
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(91)90168-v

✦ Synopsis

Primary coil dimensions can influence the accuracy of resistivity measurements made by the eddy current decay (ECD) method. Experimental results revealed that when the length of a 22.5 mm i.d. primary coil is changed from 60 to 20 mm, the corresponding measured values of resistivity increase by 4-5%. The effect occurs when there is an insubstantial background field at the sample ends. ECD measurement accuracy is better than 1% when the primary coil length to inside diameter ratio is larger than 2.2 and the sample diameter is 44% or less of the primary coil i.d. The investigation included measurements at room temperature, 77 K and 4.2 K on samples having residual resistivity ratios of 153, 340, 1010 and 7790.