IMP 4 Triaxial Fluxgate Magnetometer

This experiment used a triaxial fluxgate magnetometer. Each sensor
had dual ranges of minus to plus 32 nT and 128 nT and digitization errors of
minus to plus 0.16 and 0.64 nT, respectively. The operating range could be
changed by ground command. The sensor parallel to the spin axis was on a 1.8-m
boom and was flipped every 3.9 d to check the zero level. The other two sensors
were on a separate boom. Vector measurements were returned each 2.56 s. An
onboard autocorrelation computer was included. Autocorrelation data based on
240 samplings were returned on alternate components each 20.45 s. The experiment
worked well throughout the life of the spacecraft. However, failure of the
spacecraft optical aspect system on March 4, 1969, rendered impossible the
determination of the magnetic field direction over the last 2 months of data
acquisition. For further details, see Fairfield, J. Geophys. Res., v. 74, p.
3541, 1969. NSSDC has all the useful data that now exist from this investigation.
Hourly averaged interplanetary data also exist as part of data sets in the NSSDC
supplementary data file.

本实验采用了三轴霍尔效应磁力计。每个传感器均具备±32 nT和±128 nT的双量程范围，并分别具有±0.16 nT和±0.64 nT的数字化误差。操作范围可通过地面指令进行更改。与自旋轴平行的传感器安装于1.8米的桅杆上，每隔3.9天翻转一次以检查零点水平。其余两个传感器则安装在另一桅杆上。矢量测量数据每2.56秒返回一次。设备上还包含一个自相关计算机。基于240次采样的自相关数据每20.45秒在交替组件上返回。整个航天器生命周期内，实验均运行良好。然而，由于1969年3月4日航天器光学视向系统的故障，导致在数据采集的最后两个月内无法确定磁场方向。更多细节请参阅Fairfield所著《地球物理研究》第74卷第3541页，1969年。国家空间科学数据中心（NSSDC）保存了该调查所有现有有用的数据。每小时平均的星际数据也作为NSSDC补充数据文件中的数据集的一部分存在。