Frequency Response Extension of a Pulsed Magnetic Field Meter Based on an RL Integrator

Abstract

Introduction. Measurements of the amplitude-time characteristics of pulsed magnetic fields are required in various research and technology areas. Such measurements are carried out during pulsed magnetic field immunity testing, with the magnetic field pulse rise time being hundreds of ns, and the pulse duration to its half initial value (halfdroop) being hundreds of µs.Aim. To develop a meter of magnetic field strength with a linear conversion characteristic for measuring the pulse rise time, the pulse duration to its half-droop, and the peak value of the pulsed magnetic field strength.Materials and methods. Among several available methods for measuring pulsed magnetic field parameters, the induction method was selected. To obtain a signal proportional to the pulsed magnetic field strength, a signal from the induction transducer is integrated using a self-integrating induction transducer (RL integration) or by using an external RC integrator. The former method shows good results when measuring signals with a duration of hundreds of ns; however, this method is inefficient when measuring the parameters of longer-duration pulses. The latter method is used to determine the parameters of signals with a duration of hundreds of µs and ms; however, this method gives a large error when measuring the parameters of signals with a duration of hundreds of ns and less. The consecutive use of the two integration methods leads to an additional error in the measurement of the pulse duration to its half-drop.Results. A setup for determining the required magnetic field pulse parameters using a pulse magnetic field meter based on an RL integrator was developed. The relative measurement errors comprised 10, 10, and 9 %, respectively. The developed setup eliminates the error caused by losses in the active resistance of an induction transducer, thus enabling the pulse duration to its half-droop to be measured without additional errors under the pulse rise time of hundreds of ns and the pulse droop time of hundreds of µs.Conclusion. The development of a functional converter made it possible to extend the frequency response of a pulsed magnetic field meter based on an RL integrator to the low-frequency region.