DEVICE MEASURING WEAK MAGNETIC FIELDS ( VERSIONS ) Russian patent published in 1998 - IPC

FIELD: measurement of weak magnetic fields, specifically magnetic anomalies, representation of functions of brain, prospecting for minerals, measurement of weak currents. SUBSTANCE: device incorporates sensitive element made in the form of conductor from ferromagnetic material surrounded by inductance coil. Conductor is connected in series to A C source. Inductance coil is connected to voltmeter across its ends. Conductor of sensitive element has magnetic anisotropy perpendicular to its longitudinal axis and magnetic structure in skin layer with resulting magnetic moment directed perpendicular to its longitudinal axis in absence of external magnetic field. A C source has such current amplitude which realizes condition , where is field of current on conductor surface; M_A=H_K+N_Z•M_O is effective field of conductor anisotropy; H_K= 2K₁/M_O; K₁ is constant of conductor anisotropy; M_O is saturation magnetization of conductor; N_Z is demagnetization factor along axis of conductor. In agreement with second version ends of conductor of sensitive element are connected to voltmeter and A C source is connected to inductance coil and displays current amplitude for which condition is realized , where is longitudinal field created by current in coil on conductor surface. Use of invention makes it possible to increase sensitivity to constant field to 10^-7÷10^-8 Oe and to variable field with frequency up to 1.0 GHz to 10^-5÷10^-6 Oe at upper edge of frequency range. Range of measured fields amounts to several oersteds. Output signal of device is strictly proportional to intensity of measured magnetic field in entire range. Measurement rapidity amounts to 10^-8 s. Device can be used under conditions of impact loads in temperature range from - 50 to + 150 C. EFFECT: expanded application field, increased sensitivity of device. 2 cl, 5 dwg