Eddy current, magnetic leak, magnetic particle and ultrasonic test are the main methods used for pumping rod test.
目前，对抽油杆的自动探伤主要有涡流、漏磁、磁粉及超声方法，各有其优缺点及适用范围。
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Laser pumping magnetometers using alkali vapors as sensing medium can reach very high sensitivities in magnetic fields covering the range from the earth magnetic field to biological magnetic fields.