D-Tech Alternating Filed (AF) Demagnetizer – This machine demagnetizes rock samples using a decaying alternating magnetic field. The maximum demagnetizing field is 2000 Gauss (0.2 Tesla). The principle of the AF demagnetization procedure is to expose a specimen to an alternating magnetic field. The waveform of the alternating magnetic field is a sinusoid with a linear decrease in magnitude with time. Consequently, when samples are exposed to the elevated AF field, the natural magnetization that is stable in the samples below the applied field will be eliminated, leaving only the magnetization that is stable at elevated fields.