Measurement of uniformity

　　Measure the uniformity of the uniform region: make the output of the power supply be a certain value and keep it stable. Measure the magnetic field in the center of the coil, move the field meter smoothly in the uniform region, ensure that the probe does not tilt and rotate, and record the value of the magnetic field at each point in the uniform region. If the value is H0 center field, even in another magnetic field value of H1, so that the magnetic field of deviation for Δ H = H1 - H0, namely this point the uniformity of the magnetic field for Δ H/H0;