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Magnetic Field Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Robert L. Fagaly, Steven A. Macintyre
The induction or search coil, which is one of the simplest magnetic field sensing devices, is based on Faraday’s law. This law states that if a loop of wire is subjected to a changing magnetic flux, ϕ, through the area enclosed by the loop, then a voltage will be induced in the loop that is proportional to the rate of change of the flux: e(t)=-dϕdt
Low-Frequency Search Coil Magnetometers
Published in Krzysztof Iniewski, Smart Sensors for Industrial Applications, 2017
The operation principle of a search coil is based on Faraday’s law of induction: the voltage generated by an induction coil is proportional to the time derivative of the magnetic flux flowing through the coil area. For sinusoidal magnetic fields, () V(f)=2πfNSμaB0.
Various parameters influence on field distribution in eccentric disc-type permanent magnet machine based on analytical method
Published in Australian Journal of Electrical and Electronics Engineering, 2021
Mohammad Rajabi-Sebdani, Ahmad Darabi, Jawad Faiz
Based on (5), (13), and (15), parameters have a noticeable impact on the air gap magnetic flux density distribution and voltage in the search coil. The most important parameters are the eccentricity severity δf, the initial position of the rotor with respect to stator reference Ψ0m = (2/p)Ψ0e, where Ψ0m is the mechanical angle difference between the N pole of rotor centre and stator phase ‘a’ axis, αf is the air gap minimum length position with respect to stator reference search coil position θscm1 is its pitch, θscm2─θscm1 and Is is the stator current coils. However, addressing these parameter variations affects, solely or together, by implementing time-consuming methods such as FEA is not possible. The method introduced in the previous makes it possible to study the impacts correctly. Results obtained for the proposed motor are presented here. It is emphasised again that the search coil is a single turn, and unless mentioned otherwise, its pitch is equal to one pole pair. In addition, since the eccentricity severity, δf has already been studied in detail, its value is assumed to be 0.75 and constant for the next.
Plasma Waves Around Comets
Published in IETE Technical Review, 2022
The Institute of Space and Astronautical Science of Japan launched Sakigake on 7 January 1985 which made a flyby of comet Halley from 7 × 106 km and had a number of plasma and magnetic field observation instruments onboard such as Plasma Wave Probe (PWP), Fluxgate magnetometer to measure the interplanetary magnetic field (IMF), solar wind ion detector (SOW). The PWP was composed of two detectors – a 10 m tip-to-tip antenna and a search-coil magnetometer. The PWP also had a swept frequency receiver which analyzed the signal in 125 frequency steps from 4 to 195 kHz with a bandwidth of 1 kHz in all frequency ranges, and a 16-channel frequency analyzer (ELF, extremely low frequency) having 100 Hz constant bandwidth [44].
Plasma Waves Around Venus and Mars
Published in IETE Technical Review, 2021
NASA’s Galileo spacecraft launched in 1989 had a plasma wave instrument comprised of electric dipole antenna in the frequency range of 5–5.6 MHz, two search coil magnetometers in the frequency range of 5 Hz to 160 kHz [49] and a fluxgate magnetometer having a dynamic range from ±32 nT to ±16,384 nT onboard [50]. On its way to Jupiter, Galileo performed a Venus flyby in February 1990 and observed electron plasma oscillations using the plasma wave experiment onboard as shown in Figure 14. In this Figure, the electron plasma frequency (fpe) is marked at about 43 kHz which translates to electron plasma density ≈23 cm−3 [51].