NEW VECTOR MAGNETOMETER IN OBSERVATORY PRACTICE L. Hegymegi, 1 J. Szöllősy, 2 L. Merényi, 3 L. Szabados 3 1 MinGeo – 2 Araconsys – 3 Eötvös L. Geophysical Institute Budapest, Hungary XIVth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition and Processing, Changchun Magnetic Observatory, China, XIVth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition and Processing, Changchun Magnetic Observatory, China, September , 2010

Fluxset magnetometer ► vector magnetometer with analog output signal ► full field magnetometer ► simple construction and operation ► small size ► low power consumption XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010 Main features:

Fluxset sensor XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010 Magnetic core is saturated periodically Minimizes the memory effect Sensor response phase-modulated Higher signal/noise ratio Theoretically linear No field feedback is necessary Not the actual shape of the B-H curve utilized High reliability and wide operating temperature range No cross-talk or cross-field effect

Fluxset sensor XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Sensitivity

Gain and performance test XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Advantages ► ► Small size (~5 mm)‏ ► ► Low power consumption (~4mW)‏ ► ► Good temperature stability ► ► Full-field magnetometer ► ► Good resolution ► ► No Barkhausen noise ► ► Good experience in production XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Disadvantages ► Not yet experience in long-term stability ► Not yet experience in low field/low noise applications (geomagnetic field range)‏ XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Different models of Fluxset magnetometer XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Award

Experimental setup in THY XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010 SERVER/INTERNET MAGREC-4 24 bit A/D Fluxset T2-10Thermometer GPS Bartington MAG 01H

Experimental setup in THY XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

First results XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010 MAG 01H FXS T2-10 DMI FGE temperature 27/8/10 Y component

First results XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Future application plans ► Combined observatory magnetometer (dIdD + FXS) for fast magnetic recording (1 Hz) with good baseline stability ► D/I theodolite equipped with three component FXS ► Field instrument for magnetic survey ► Gradiometer for magnetic survey XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010

Software for calulation of magnetic vector data in a combined system XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010 dIDD magnetometer: slow but measures full-field, with good baseline stability fluxset or fluxgate magnetometer: faster, but can have lower baseline stability The fast magnetometer XYZ/HDZ data are continously re-calibrated with dIdD magnetometer XYZ/HDZ data using the last several minutes or hours recording (either raw data or minute averages). For X component: mx and a are continousely recalculated using linear regression: Xfast = XdIdD * mx + a Change of m and a can reflect temperature dependence of the magnetometer. The method built into the data acquisition program. The procedure is tested and now we have to find the optimal calibration period and get long-term experience with the method.

Conclusions ► More time needed for the experiments ► Industrial version needs more modification/ improvements for geomagnetic applications ► It seems to be possible to reduce the noise as its main source is in the electronics ► Because of its simplicity, small size and low power consumption it is promising XVIth Geomagnetic Observatory Workshop, Changchun, China, 2010