Memoirs of the Kakioka Magnetic Observatory Vol.12 No.02， p.85, December, 1966

Observation on H- and Z- Component and Compensating Magnetic Field of Vector Proton Magnetometer, MO-P, for Routine Use

Sakuraoka, T.

Abstract

 Vector proton magnetometer, MO−P, has been installed in the Kakioka Magnetic Observatory for routine use. With this magnetometer H and Z components and total force F can be measured with the accuracy of 0.3γ. Full detail will be published elsewhere.
  Here necessary improvement of initial device of compensating magnetic field will be reported together with observations by new device.
  When H or Z component is measured the perpendicular component should be cancelled with a Helmholtz-coil. Stability of compensating field produced by the coil is an important factor for the accuracy of observation.
  The initial device of compensating field supply is not enough stable when the current of coil is cut off or changed. The large change of compensating field occurs at that time.
  Nevertheless cut-off or change of the current is necessary for the routine observation of H or Z. This large change, which is considered to be due to the change of coil current, has been reduced considerably by the use of newly designed power supply for the coil.
  In this case changes at the switching of the current are not found practically, and the stability of coil current is about 1 × 1O-2mA (7γ) per hour, or 3×l0-３mA (2γ) per few minutes.
  The directly observed value F of the total force is compared with the computed value F'＝（H２+Z２）１／２ from the respective observed value H and Z components.
  The absolute value of difference |F−F'| is 0.4γ in maximum and 0.1γ in average.

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