共查询到20条相似文献，搜索用时 218 毫秒
1.
J. Bitterly J. M. Cantin R. Schlich J. Folques D. Gilbert 《Surveys in Geophysics》1984,6(3-4):233-239
A new portable magnetometer theodolite with fluxgate sensor has been developed for measuring the components of the earth's magnetic field. With this instrument, used as a null detector, it is possible to make absolute measurements of declination (D) and inclination (I). The compensation of the main magnetic field allows direct intensity measurements (H, X, Y, Z components); in this case the calibration is made by reference to a proton magnetometer.The observation procedure is particularly easy and quick. The accuracy is better than 5 sec of arc forD andI and better than 1 nT for direct intensity measurements. 相似文献
2.
为了检测GSM-19T质子旋进磁力仪主要技术指标及参数的性能,2019年10月17—21日河北省地震局红山基准台以GSM-19W Overhauser磁力仪为标准仪器,对40台GSM-19T质子旋进磁力仪地磁总强度F,通过同步连续采样观测和仪器差进行了比测,计算其差值和均方差。结果表明,大部分测量仪器与标准仪器具有较好的一致性和稳定性,地磁总强度F均方差和仪器差均较小,各项技术指标参数符合大纲测试要求,测量仪器比测合格,可为基站观测和野外流动观测提供准确可靠的数据和仪器保障;小部分测量仪器有漂移,地磁总强度F均方差稍大。 相似文献
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HELMUT LINSSER 《Geophysical Prospecting》1970,18(1):119-133
The principle of optical pumping allows the design of magnetometers with high sensitivity. When mapping the field of the total magnetic force, it is no longer possible to make full use of the accuracy of the instruments because the accuracy of the reduction of the diurnal variation is limited. By simultaneously recording with two instruments in different altitudes, the vertical gradient can be measured which doe's not depend on the time variation of the magnetic field. Therefore, the gradiometer seems to be a more adequate tool for oil exploration than the magnetometer. It is investigated in this article whether the results of this gradiometer or the measurements of the total magnetic field by the high sensitive magnetometer are more useful in oil exploration. The article comes to the conclusion that for most problems of oil exploration the total magnetic field is a more valuable unit than the vertical gradient measured directly by the gradiometer. The total magnetic field allows a better investigation of the tectonics than the vertical gradient. The apparent advantages of the gradiometer claimed by its supporters are mainly based on inconsistent mathematical concepts. 相似文献
5.
Summary The degree of astaticism is the fundamental parameter of an astatic magnetometer, an instrument used in geophysics for magnetic measurements of rock specimens. The degree of astaticism is formulated with a view to the vectorial character of the defining quantities and with a view to the effect of the geomagnetic field. As regards measuring the parameter, the mirror method is given, which makes use of the positive and negative orientation of the astatic system relative to the north or east. The measure of the value of the parameter is the change of the sensitivity of the system and the deflection of its zero position, compensated for by the magnetic field of the calibration coil. The problem of the degree of astaticism is treated complexly, inclusive of the measurement of the parameter, which in practice is of fundamental importance for adjusting the systems for manufacturing astatic magnetometers. 相似文献
6.
Yu. P. Tsvetkov O. M. Brekhov S. V. Filippov T. N. Bondar A. A. Ivanov A. V. Krapivnyi N. S. Nikolaev 《Geomagnetism and Aeronomy》2007,47(4):510-514
The errors of measurements of vertical geomagnetic gradients at altitudes of 20–40 km, using a balloon magnetic gradiometer with a 6-km-long measuring base oriented along gravity, have been studied in the work. The errors related to the deviation of the measuring base position relative to the vertical have been studied during the real balloon flight with the help of the navigation GPS receivers. The deviations of the measuring base within 5°, which can sometimes reach 15°, have been obtained. This results in a decrease in the magnetic gradient measurement accuracy due to the errors introduced in the specification of the normal magnetic field used to detect magnetic anomalies. To eliminate this error, a GPS receiver was built in each magnetometer in order to observe magnetometers during synchronous measurements and to correct the measurements for the normal magnetic field. It has been indicated that the effect of deviations of the measuring base position on the results is not more than 2% of the measured value at such organization of a gradiometer. 相似文献
7.
磁通门磁力仪的零位偏移量在卫星轨道上会因诸多因素而发生改变.为此,基于剪切阿尔芬波动不改变总磁场强度这一特征的Davis-Smith方法被提出用于计算磁力仪的零位补偿.实际上,行星际空间中没有纯粹的阿尔芬波动.本文采用数值模拟分析了存在小的压缩波动情况下,阿尔芬波动的幅度、周期和相位以及数据窗口时间长度等对Davis-Smith方法计算零位补偿的影响.我们发现,只有当阿尔芬波动的周期与压缩波动周期相同时,阿尔芬波动的性质会对零位补偿的计算产生不可忽视的误差.阿尔芬波动的幅度越大,零位补偿的误差越小.磁场各分量零位补偿的误差大小还会受到阿尔芬波动初始相位的影响.此外,数据窗口时间长度越长,则零位补偿误差趋于减小至真实值. 相似文献
8.
The KLY-4S Kappabridge and KLF-4A Magnetic Susceptibility Meter enable automated measurement of susceptibility variation with
field in the ranges of 2–450 A/m and 5–300 A/m (in effective values), respectively. Unfortunately, the measurement accuracy
decreases with decreasing field and it is not easy to decide whether the susceptibility variation at the lowest fields is
natural phenomenon or results from measuring errors. To overcome this problem, the accuracies of both the above instruments
were investigated experimentally using artificial specimens (mixture of pure magnetite and plaster of Paris) with variable
susceptibilities ranging from 1 × 10−5 to 5 × 10−2. The complete curve of the field variation of susceptibility of each specimen was measured 10 times and the relative error
was calculated for each field.
In the KLY-4S Kappabridge, in specimens with susceptibilities higher than 100 × 10−6, the relative errors are lower than 3% in all fields and lower than 1% in the fields stronger than 10 A/m. In the KLF-4A
Magnetic Susceptibility Meter, in relatively strongly magnetic specimens with susceptibilities 5 × 10−4 to 5 × 10−2, the relative error is less than 1.5% in the entire field range. While the former instrument is convenient for investigating
almost all rock types, the latter instrument is convenient for measuring moderately and strongly magnetic specimens.
To facilitate work with field variation of susceptibility curves, showing variable accuracies with field, the programme FieldVar
was written. One of its options is plotting the measured data with corresponding field-variable error bars. In this way, a
tool is offered for interpreting such susceptibility changes that are sound and reasonable from the point of view of measuring
accuracy. 相似文献
9.
卫星所携带的磁通门磁强计会随时间发生零位漂移,因此需要对其进行补偿.基于行星际磁场的剪切阿尔芬波动特性,利用Davis-Smith方法可计算磁强计的零位磁场.本文利用数值模拟,分析了总磁场幅度BT及压缩波动对Davis-Smith方法所产生零位补偿的误差特征.我们发现,BT越大,零位补偿误差越大;且当压缩波动频率和剪切波动频率不同时,磁场各分量的零位补偿之间的比值与对应背景磁场的比值近似相等;压缩波动的幅度越小,零位补偿的误差趋于更小;此外,压缩波动的频率和初始相位等也会影响零位补偿的误差.这些误差特征可为提高零位补偿的可靠性提供重要的理论依据. 相似文献
10.
The most widespread instrument used today for the measurement of quasi-stationary and slowly fluctuating vector magnetic fields is a flux-gate magnetometer (FGM). The most important parameter characterizing the magnetometer quality is its magnetic noise—its threshold sensitivity or its own noise level (NL). Based on the results of experimental research, we may state that the FGM NL mainly depends on the quality of the magnetic material used for FGM sensor core. The “solid liquid” model explaining the nature of magnetic noise is proposed and substantiated. It is demonstrated that special attention has to be paid to the annealing of the core. A new effect—termed gamma-magnetic normalization—is discovered and discussed. It is shown that the magnetometer NL depends not only on the core length and volume but also on the excitation mode of the core. Besides, the ways to improve other factors, such as power consumption and thermal drift which must be taken into account in order to create a FGM with the highest possible performance, are discussed. Some examples are given of the parameters of present advanced FGMs for geophysical uses. 相似文献
11.
Frank E. Senftle Arthur N. Thorpe Charles Briggs Corrine Alexander Jean Minkin David L. Griscom 《Earth and Planetary Science Letters》1975,26(3):377-386
The magnetic susceptibility of a terrestrial, synthetic and lunar ilmenite specimen has been measured from 4 to 300 K. All specimens had a single Néel temperature transition which ranged from 56 to 57.7 K. In one case the powdered specimen was partially aligned in the magnetic field prior to the susceptibility measurements and the Néel transition was observed to shift to 60 K indicating magnetic anisotropy. A study of several magnetic parameters calculated from the experimental data showed gross impurities in the terrestrial specimen, single-domain to multi-domain metallic iron in the synthetic specimen, and a small amount of superparamagnetic metallic iron in the lunar sample. No multidomain iron was observed in the lunar ilmenite. The results of electron spin resonance measurements were also in general agreement with these findings. Because of the absence of Fe3+ compared to most terrestrial samples it is suggested that the anisotropic magnetic parameters be determined on lunar ilmenite when a large enough single crystal becomes available. 相似文献
12.
Summary A differential rotating mill for the measurement of electric fields has been designed and built. The instrument was specifically designed to be insensitive to the effects of space charge and frictional charging so that it could operate in the environment of an active thundercloud. The electric field range of the device is 100 to 250,000 volts per meter, (however, corona should occur before the maximum measurable field is reached) and the conductivity range is approximately (depending on the electric field) 10–11 to 10–13 mhos/meter.Forty of these devices have been parachuted into active, and potentially active, thunderclouds around Tucson, Arizona. Although the presently available measurements are too few for an unequivocal conclusion, the data strongly support the presence of very high conductivities in thunderstorms.This research was supported by the Atmospheric Sciences Section, National Science Foundation under Grant GA-701. 相似文献
13.
磁共振地下水探测(MRS)技术能直接测量水中氢质子的拉莫尔进动,可表征地下水含水量和介质孔隙度等信息,因而获得了广泛应用.然而,MRS信号微弱,实际探测中电磁噪声强度大,若噪声未被有效去除,会导致后续水文参数解释不准确,采用“8”字形线圈或运用带参考线圈的噪声抵消等方法可抑制噪声干扰,但这些方法消噪效果的好坏取决于电磁噪声的空间分布.另外,在强噪声或多噪声源环境下应用MRS方法,选择恰当的探测位置对提高探测效率以及增加探测结果的有效性具有重要意义.因此,本文使用双通道噪声采集装置在实验前记录环境中的电磁噪声,通过双通道参考技术推导同一时刻不同测点的噪声强度,再得到测区电磁噪声分布结果,该噪声分布情况对MRS方法探测方式的选取具有指导性的作用.同时,可根据噪声分布情况为探测线圈选择最佳测点以避开噪声强度大的区域,进而提高采集信号的信噪比.最后,通过采集室外环境下的电磁噪声,验证本文提出的基于双通道参考技术的电磁噪声分布规律研究方法的有效性,为可靠高效地开展磁共振地下水探测提供了新的技术手段. 相似文献
14.
Summary A portable magnetometer of the fluxgate type is described, which is capable of measuring in the field the direction and intensity of remanent magnetization of rock samples of 2 cm diameter with an accuracy of the order of 6° for intensities of 10–3 emu/cc or more. The measurement and calculation can be carried out in less than five minutes, and a precision of the order of 2° can be obtained if more readings are taken so that ten minutes are required for a complete measurement. The chief limitation to the precision of measurement was found to be inhomogeneity of magnetization of the specimens. The instrument has been used to estimate stability of natural remanent magnetization where A.C. cleaning apparatus is not available, and the method of doing so is briefly described.Now with English Electric Computers. 相似文献
15.
Application of Hilbert‐like transforms for enhanced processing of full tensor magnetic gradient data 
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下载免费PDF全文 M. Schiffler M. Queitsch R. Stolz H.‐G. Meyer N. Kukowski 《Geophysical Prospecting》2017,65(Z1):68-81
Commonly, geomagnetic prospection is performed via scalar magnetometers that measure values of the total magnetic intensity. Recent developments of superconducting quantum interference devices have led to their integration in full tensor magnetic gradiometry systems consisting of planar‐type first‐order gradiometers and magnetometers fabricated in thin‐film technology. With these systems measuring directly the magnetic gradient tensor and field vector, a significantly higher magnetic and spatial resolution of the magnetic maps is yield than those produced via conventional magnetometers. In order to preserve the high data quality in this work, we develop a workflow containing all the necessary steps for generating the gradient tensor and field vector quantities from the raw measurement data up to their integration into highresolution, lownoise, and artefactless two‐dimensional maps of the magnetic field vector. The gradient tensor components are processed by superposition of the balanced gradiometer signals and rotation into an Earth‐centred Earth‐fixed coordinate frame. As the magnetometers have sensitivity lower than that of gradiometers and the total magnetic intensity is not directly recorded, we employ Hilbert‐like transforms, e.g., integration of the gradient tensor components or the conversion of the total magnetic intensity derived by calibrated magnetometer readings to obtain these values. This can lead to a better interpretation of the measured magnetic anomalies of the Earth's magnetic field that is possible from scalar total magnetic intensity measurements. Our conclusions are drawn from the application of these algorithms on a survey acquired in South Africa containing full tensor magnetic gradiometry data. 相似文献
16.
K.-H. Fornacon H. U. Auster E. Georgescu W. Baumjohann K.-H. Glassmeier G. Haerendel J. Rustenbach M. Dunlop 《Annales Geophysicae》1999,17(12):1521-1527
The special feature of the ringcore fluxgate magnetometer on Equator-S is the high time and field resolution. The scientific aim of the experiment is the investigation of waves in the 10–100 picotesla range with a time resolution up to 64 Hz. The instrument characteristics and the influence of the spacecraft on the magnetic field measurement will be discussed. The work shows that the applied pre- and inflight calibration techniques are sufficient to suppress spacecraft interferences. The offset in spin axis direction was determined for the first time with an independent field measurement by the Equator-S Electron Drift Instrument. The data presented gives an impression of the accuracy of the measurement. 相似文献
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Optically pumped vapour magnetometers have an orientation dependency in measuring the scalar component of the ambient magnetic field which leads to challenges for integration with mobile platforms. Quantifying the three-dimensional attitude variations (yaw, pitch and roll) of an optically pumped vapour magnetometer, while in-flight and suspended underneath a rotary unmanned aerial vehicle, aids in the successful development of reliable, high-resolution unmanned aerial vehicle magnetometry surveys. This study investigates the in-flight three-dimensional attitude characteristics of a GEM Systems Inc. GSMP-35U potassium vapour magnetometer suspended 3 m underneath a Dà-Jiāng Innovations S900 multi-rotor unmanned aerial vehicle. A series of unmanned aerial vehicle-borne attitude surveys quantified the three-dimensional attitude variations that a simulated magnetometer payload experienced while freely (or semi-rigidly) suspended underneath the unmanned aerial vehicle in fair weather. Analysis of the compiled yaw, pitch and roll data resulted in the design of a specialized semi-rigid magnetometer mount, implemented to limit magnetometer rotation about the yaw axis. A subsequent unmanned aerial vehicle-borne magnetic survey applying this specialized mount resulted in more than 99% of gathered GSMP-35U magnetic data being within industry standards. Overall, this study validates that maintaining magnetometer attitude variations within quantified limits (±5° yaw, ±10° pitch and roll) during flight can yield reliable, continuous and high-resolution unmanned aerial vehicle-borne magnetic measurements. 相似文献
19.
František Hrouda Alan Stephenson Leo Woltär 《Physics of the Earth and Planetary Interiors》1983,32(3):203-208
The magnetic anisotropy of several artificially constructed samples has been measured with different types of instruments in several laboratories. Susceptibility bridge determinations have given consistent results, but the magnitude of the anisotropy determined by the Digico anisotropy delineator is incorrect. For future measurements with this instrument it is necessary to make either a simple calibration change or to make a minor change in the associated computer program. A set of equations for correcting the old published data is given. 相似文献
20.
Measurement of magnetic properties of steel sheets 总被引：1，自引：0，他引：1
Magnetic methods are used in detection of environmental, engineering and military objects fabricated of thin ferromagnetic sheets having volume susceptibilities higher than 100 SI units. Magnetic modelling of such objects would be advantageous, but it requires knowledge of the susceptibility and remanence values of sheet materials, which is scarce. We introduce a magnetometer method for the determination of susceptibility and remanence on thin steel samples. The area of the sample must be so large that its within-sheet magnetization remains below the saturation state. The measurements are made in normal office surroundings in the Earth's magnetic field with an ordinary fluxgate magnetometer. The square-shaped sheet samples measured in this work have an edge length of 17.5 cm and a thickness in the range 0.5–1.0 mm. During the measuring procedure the sample is placed in four positions on a subvertical measurement board. For each position, the magnetic field in the dip direction of the board plane is measured on the opposite sides of the sample. The secondary field values are averaged for each sample position in order to reduce the effect of sample inhomogeneities. With these data, the susceptibility and remanence of the sample in its edge directions are then determined, based on a model curve which is calculated numerically using thin-sheet integral equations. The susceptibilities measured for different steel types (cold rolled and hot-dip zinc-coated steel sheets) varied in the range 200–500 SI units, and the remanence varied in the range 1000–20 000 A/m. No systematic differences were observed between the magnetic properties of various steel types. The repeatability of the susceptibility measurements was good (variations < 5%) but the remanence could be changed by 50% between repeated determinations. The measured susceptibility range signifies that pieces of steel with a typical thickness of 0.5 mm remain below magnetic saturation when their edge dimension is larger than 5 cm. Therefore magnetic modelling of larger steel pieces must be made using the thin-sheet theory with known magnetic properties, whereas smaller saturated pieces can be alternatively modelled as an equipotential system. 相似文献