If place an open magnet in a magnetic field, then the magnetic flux from the detection of induction coil which has a certain distance from the sample can be regarded as the sample of external magnetized field and disturbance caused. In most cases most researchers are more concerned about the disturbance quantity measurement. In the field of magnetic survey, the method of distinguish the disturbance and the environment magnetic field has a lot of kinds. For example, you can make samples to be tested in a certain way of vibration, the detection of induction coil to sample number will have rapidly alternating magnetic communication, keeping the environment magnetic field and other amount not to make any changes, and this goal can be realized.
This is a complete dc magnetic property of magnetic materials with ac signal measurement method. We can directly deduct the environment of constant magnetic field by the test. And the coil position, as well as vibration frequency and amplitude all can be controlled by the optimized useful signal. Because in the process of test, environment of constant magnetic field can be directly deduct, whereas the useful signal could be optimized by controlling the coil position, vibration frequency and amplitude. Based on the above theory, the drilling shale shaker , which is a measuring instrument, is sensitive to magnetic moment.
Drilling shale shaker maintenance can be seen in many ways. It uses electromagnetic induction principle, measures a set of detecting coil at a fixed frequency and amplitude of micro vibration of the magnetic moment of the sample. For a small enough samples, it in detecting coil vibration generated by the induced voltage and magnetic moment, amplitude and vibration frequency is proportional to the sample. On the basis of the guarantee amplitude and vibration frequency constant, Phase-locked amplifier was used to measure the voltage, can calculate the magnetic moment of the sample under test.
Drilling shale shaker maintenance can be divided into different aspects, magnetic moment of the commercial product sensitivity is often better than 10 to 9 am2, accurately adjust the sample and the degree of coupling coil can make the parameters as low as 10 to 12 am2., on the other hand, uses the drilling shale shaker upper limit for the measurement of magnetic moment can reach 0.1 Am2 or more.
Compared with closed-circuit loop measurement, we should pay more attention to drilling shale shaker maintenance, because there is no zero drift problem, test process can last for a few minutes. Shortcoming in also exits - samples with detecting coil, vibration rod sample around, the electromagnet gap is significantly lower than the biggest magnetic field measurement that closed circuit can get. In order to improve the induction sensitivity, in the cases of saddle area, appropriate detection coil can certainly as far as possible close to the position of the sample, so as to reduce gap. However, on the other hand, a first plane and the distance of the coil to the sample should not be too small, in order to reduce the effects of the mirror. Most vacuum degasser uses drilling shale shaker electromagnet as field source in the closed circuit measurement part, we already mentioned the limitation of the scope of electromagnet for magnetic field strength, the problem for drilling shale shaker is more prominent. It is easy to understand, drilling shale shaker magnet pole head is put among the coil structure, it will inevitably increase the distance between the poles, so that the electromagnet maximum magnetic field will drop, and mirror effect will increase this trend.