Magnetic Field Observations (MAG-A)

This investigation used a triaxial fluxgate magnetometer (MAG-A),
similar to one on board DE 2, to obtain vector magnetic
field data needed to study the magnetosphere-ionosphere-
atmosphere coupling.

The primary objective of this
investigation was to obtain measurements of field-aligned
currents in the auroral oval and over the polar cap at two
different altitudes. This was accomplished using the two
spacecraft and correlations of these measurements with
observations of electric fields, plasma waves, suprathermal
particles, thermal particles, and auroral images obtained from
investigation 81-070A-03. Ultra low frequency (ULF) waves were
also studied.

The magnetometer incorporated its own 12-bit
analog-to-digital converter, a 4-bit digital compensation
register for each axis, and a system control to generate a 48-
bit data word consisting of a 16-bit representation of the
field measured along each of the three magnetometer axes. Track
and hold modules were used to obtain simultaneous samples on
all three axes. Instrument bandwidth was 25 Hz. The instrument
dynamic range was plus or minus 6.2E4 nT, and the resolution
was plus or minus 1.5 nT in the 6.2E4 nT region, plus or minus
0.25 nT in the 1.E3 nT region, and plus or minus 0.02 nT in the
80 nT region. The magnetometer's digital compensation of the
ambient field was nominally in 8.E3 nT increments.

Further
details are in W. H. Farthing et al., Space Sci. Instrum., v.
5, n. 4, p. 551, 1981.

本研究采用三轴霍尔效应磁力计（MAG-A），与DE 2卫星上的设备相似，以获取研究磁层-电离层-大气耦合所需的矢量磁场数据。此次研究的主要目标是获取在极光椭圆区和极冠上不同高度处的场向电流测量值。通过使用两颗航天器以及将这些测量值与来自研究81-070A-03的电场、等离子体波、超热粒子、热粒子和极光图像的观测结果进行相关性分析，实现了这一目标。同时，还对超低频（ULF）波进行了研究。该磁力计内置12位模数转换器，每个轴向配备有4位数字补偿寄存器，并设有系统控制，以生成由每根磁力计轴向测量的16位场表示组成的48位数据字。通过跟踪和保持模块，在所有三个轴向获取了同时样本。仪器带宽为25赫兹。仪器的动态范围为±6.2×10^4纳特，分辨率在±6.2×10^4纳特区域为±1.5纳特，在±1×10^3纳特区域为±0.25纳特，在±80纳特区域为±0.02纳特。磁力计对环境场的数字补偿以8×10^3纳特为增量。更多详细信息可参考W. H. Farthing等人的文章，发表在《空间科学仪器》杂志第5卷第4期，第551页，1981年。