Extremely achievable parameters of quartz torsion variometer magnetometers are investigated. Influence of instability and noise of the opto-electronic converter on a threshold of sensitivity of a magnetometer with the negative feedback (NF) is considered and extreme values of a sensitivity threshold of the magnetometer are estimated for different magnetic materials used, depths of NF and the demanded frequency range of measurements. Criteria for optimization of the sizes and a form of the magnets are determined by a condition of a maximum relation of the magnetic moment to the moment of inertia. Theoretical and experimental estimates of noise level of magnetometers on a base of vicalloy and samarium-cobalt are given. It is shown that for threshold sensitivity of the magnetometer about 1~pT, the frequency range of the magnetometer with a sensor on a base of vicalloy is limited by a frequency about 1.6~Hz, samarium-cobalt -- 6.4~Hz. The received values of a frequency and threshold sensitivity for the specified magnetic materials completely meet the requirements of Intermaget for one-second data and are probably the extreme values for quartz variometers with the opto-electronic converter of angular movements.
Quartz magnetic variometer, sensitivity, frequency range
1. Askerov, E. N., et al. CAIS digital automatic measuring station // Geophysical Equipment, issue 91, Mikhaylov G.~N. (Ed.) - Moscow: Nedra., 1989. - p. 3.
2. Bobrov, V. N. The universal highly stable sensing device with a zero temperature coefficient for the magnetometers, variometers and microvariometers recording any component of a terrestrial magnetic field // Terrestrial Magnetism of II. Theoretical Bases of a Magnetometric Research Technique of Crust and Geomagnetic Measurements, IZMIRAN, issue 18(28) - Moscow: IZMIRAN., 1961. - p. 55.
3. Bryunelli, B. E., et al. Observations of short period variations of an electromagnetic field of the Earth, // Izvestija Academy of Sciences of the USSR, Geophysics, 1959. - no. 8 - p. 1206.
4. Hegymegi, L., Drimusz, L., Koros, Z. Eotvos Institute DIMARS Quartz Magnetometer // Proc. of the Int. Workshop on Magnetic Observatory Instruments, Ottawa, Canada, 30 July-9 August 1986 - Ottawa: IWMOI., 1986. - p. 25.
5. Jankowski, J., et al. Long-Term Stability of a Torque-Balance Variometer with Photoelectric Converters in Observatory Practice, // Geophysical Surveys, 1984. - v. 6 - no. 3-4 - p. 367.
6. Klyuev, A. S. Automatic Control - Moscow: Energy., 1973. - 391 pp.
7. Marianiuk, J. Photoelectric Converter for Recording the Geomagnetic Field Elements: Construction and Principles of Operation - Poland: Publ. Inst. Geophys. Pol. Acad. Sci.., 1977. - 114 pp.
8. Odintsov, V. I., Kolesnik, V. E. Digital magnetovariation station CMVS-2 // Geomagnetic Researches - Moscow: Radio and Communication., 1982. - p. 22.
9. Rabinovich, S. G. Galvanometric Autocompensation Devices - Moscow: Standards Publishing House., 1972. - 36-40 pp.
10. Yanovsky, B. M. Terrestrial Magnetism of II. Theoretical Bases of a Magnetometric Research Technique of Crust and Geomagnetic Measurements - Leningrad: Publishing house of the Leningrad University., 1963. - 392-413 pp.
