Analysis of the magnetic and ringing properties of nickel-zinc-ferrite for use in pulsed nuclear magnetic resonance applications

Pulsed nuclear magnetic resonance (NMR) techniques are used in the oil industry to survey land for hypogeous fluid deposits. Inductive sensors act as both transmitters and receivers to detect these deposits and often require a magnetic core to enhance the quality of signals recorded. Ideal magnetic properties of a core include a high magnetic permeability and saturation magnetization. However, it is also observed that the magnetic core responds to the input signals producing oscillations which interfere with the NMR measurements, thus necessitating reduction of ringing amplitude and increase in peak linewidth. If not suppressed, the ringing of the core would cause significant noise in measurements and render the device inoperative for some time. To meet the criteria of the application, sintered nickel-zinc-ferrite (Ni-Zn ferrite) powder set in epoxy were chosen for the core material. The relative amounts of nickel and zinc were varied and the compositional effect on magnetic and ringing properties were analyzed to determine an optimal core composition. In this work, an analysis of the magnetic and ringing properties of Ni-Zn ferrites suited for pulsed NMR systems will be presented.