Planetary Magnetic Field Measurements: Missions and Instrumentation

Balogh, A.

doi:10.1007/s11214-010-9643-1

Cited by 60 publications

(27 citation statements)

References 234 publications

(264 reference statements)

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“…Many magnetometer applications, such as searches for permanent electric dipole moments [5], detection of NMR signals [6], and low-field magnetic resonance imaging [7], require sensitive magnetic measurements in a finite magnetic field. In addition, scalar magnetometers measuring the Zeeman frequency are unique among magnetic sensors in being insensitive to the direction of the field, making them particularly suitable for geomagnetic mapping [8] and field measurements in space [9,10]. The sensitivity of scalar magnetometers has been relatively poor, as summarized recently in [11].…”

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confidence: 99%

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

et al. 2013

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Scalar atomic magnetometers have many attractive features but their sensitivity has been relatively poor. We describe a Rb scalar gradiometer using two multi-pass optical cells. We use a pump-probe measurement scheme to suppress spin-exchange relaxation and two probe pulses to find the spin precession zero crossing times with a resolution of 1 psec. We realize magnetic field sensitivity of 0.54 fT/Hz 1/2 , which improves by an order of magnitude the best scalar magnetometer sensitivity and surpasses the quantum limit set by spin-exchange collisions for a scalar magnetometer with the same measurement volume operating in a continuous regime. PACS numbers: 07.55.Ge, 42.50.Lc, 32.30.Dx Alkali-metal magnetometers can surpass SQUIDs as the most sensitive detectors of magnetic field, reaching sensitivity below 1 fT/Hz 1/2 [1, 2], but only if they are operated near zero magnetic field to eliminate spin relaxation due to spin-exchange collisions [3,4]. Many magnetometer applications, such as searches for permanent electric dipole moments [5], detection of NMR signals [6], and low-field magnetic resonance imaging [7], require sensitive magnetic measurements in a finite magnetic field. In addition, scalar magnetometers measuring the Zeeman frequency are unique among magnetic sensors in being insensitive to the direction of the field, making them particularly suitable for geomagnetic mapping [8] and field measurements in space [9,10]. The sensitivity of scalar magnetometers has been relatively poor, as summarized recently in [11]. The best directly measured scalar magnetometer sensitivity is equal 7 fT/Hz 1/2 with a measurement volume of 1.5 cm 3 [12], while estimates of fundamental sensitivity per unit measurement volume for various types of scalar alkali-metal magnetometers range from several fT cm 3/2 /Hz 1/2 [13, 14] to about 1 fT cm 3/2 /Hz 1/2 [12]. Here we describe a new type of scalar atomic magnetometer using multi-pass vapor cells [15,16] and operating in a pulsed pump-probe mode [17] to achieve magnetic field sensitivity of 0.54 fT/Hz 1/2 with a measurement volume of 0.66 cm 3 in each multi-pass cell. The magnetometer sensitivity approaches, for the first time, the fundamental limit set by Rb-Rb collisions. We also develop here a quantitative method to analyze significant effects of atomic diffusion on the spectrum of the spin-projection noise in vapor cells with buffer gas using a spin time-correlation function.The sensitivity of an atomic magnetometer, as any other frequency measurement, is fundamentally limited by spin projection noise and spin relaxation [18]. For N spin-1/2 atoms with coherence time T 2 the sensitivity after a long measurement time t ≫ T 2 is given by δB = 2e/N T 2 t/γ, where γ is the gyromagnetic ratio. Spin squeezing techniques can reduce this uncertainty by a factor of √ e, but do not change the scaling with N [18-20]. The number of atoms can be increased until collisions between them start to limit T 2 . Writing T −1 2 = nσv, where n is the density of atoms, σ is the spin relaxation c...

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confidence: 99%

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

et al. 2013

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“…The on-ground calibration of vector magnetometers based on the fluxgate and especially of the AMR principle is mandatory to resolve the relation between the measured and the true magnetic field vector at the position of the sensor. The mathematical relation between the two vectors in the most compact form is expressed by a 3 × 3 transformation matrix and an offset vector (e.g., Balogh 2010). The transformation matrix includes information about scale factors, orthogonality and alignment.…”

Section: On-ground Calibrationsmentioning

confidence: 99%

Space Weather Magnetometer Aboard GEO-KOMPSAT-2A

Magnes

Hillenmaier²,

Auster

et al. 2020

Space Sci Rev

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The South Korean meteorological and environmental satellite GEO-KOMPSAT-2A (GK-2A) was launched into geostationary orbit at $128.2^{\circ}$ 128.2 ∘ East on 4 December 2018. The space weather observation aboard GK-2A is performed by the Korea Space Environment Monitor. It consists of three particle detectors, a charging monitor and a four-sensor Service Oriented Spacecraft Magnetometer (SOSMAG). The magnetometer design aims for avoiding strict magnetic cleanliness requirements for the hosting spacecraft and an automated on-board correction of the dynamic stray fields which are generated by the spacecraft. This is achieved through the use of two science grade fluxgate sensors on an approximately one meter long boom and two additional magnetoresistance sensors mounted within the spacecraft body. This paper describes the instrument design, discusses the ground calibration methods and results, presents the post-launch correction and calibration achievements based on the data which were acquired during the first year in orbit and demonstrates the in-flight performance of SOSMAG with two science cases. The dynamic stray fields from the GK-2A spacecraft, which was built without specific magnetic cleanliness considerations, are reduced up to a maximum factor of 35. The magnitude of the largest remnant field from an active spacecraft disturber is 2.0 nT. Due to a daily shadowing of the SOSMAG boom, sensor intrinsic offset oscillations with a periodicity up to 60 minutes and peak-to-peak values up to 5 nT remain in the corrected data product. The comparison of the cleaned SOSMAG data with the Tsyganenko 2004 magnetic field model and the magnetic field data from the Magnetospheric Multiscale mission demonstrates that the offset error is less than the required 5 nT for all three components and that the drift of the offsets over 10 months is less than 7 nT. Future work will include a further reduction of the remaining artefacts in the final data product with the focus on lessening the temperature driven sensor oscillations with an epoch based identification and correction.

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“…Similar instruments have also been flown on Rosetta Lander (Biele & Ulamec 2007) and the Mir Space Station. This instrument is capable of measuring in interplanetary space as well as inside the magnetic field of Venus (Balogh 2010). The range of the outer sensor is ±262 nT with an accuracy of 8 pT and the onboard sensor with a range of ±524 nT, also with an accuracy of 8 pT.…”

Section: Fluxgate Magnetometermentioning

confidence: 99%

A Space weather information service based upon remote and in-situ measurements of coronal mass ejections heading for Earth

Ritter

Meskers

Miles

et al. 2015

J. Space Weather Space Clim.

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The Earth's magnetosphere is formed as a consequence of interaction between the planet's magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past 40 years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs), can significantly disturb the Earth's magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field's orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CME properties. The obtained data can additionally be used for updating scientific models. This update is the mission's secondary objective. In-situ measurements are performed using a Solar Wind Analyzer instrumentation package and fluxgate magnetometers, while for remote measurements coronagraphs are employed. The proposed instruments originate from other space missions with the intention to reduce mission costs and to streamline the mission design process. Communication with the six identical spacecraft is realized via a deep space network consisting of six ground stations. They provide an information service that is in uninterrupted contact with the spacecraft, allowing for continuous space weather monitoring. A dedicated data processing center will handle all the data, and then forward the processed data to the SSA Space Weather Coordination Center which will, in turn, inform the general public through a space weather forecast. The data processing center will additionally archive the data for the scientific community. The proposed concept mission allows for major advances in space weather forecasting time and the scientific modeling of space weather.

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Planetary Magnetic Field Measurements: Missions and Instrumentation

Cited by 60 publications

References 234 publications

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

Subfemtotesla Scalar Atomic Magnetometry Using Multipass Cells

Space Weather Magnetometer Aboard GEO-KOMPSAT-2A

A Space weather information service based upon remote and in-situ measurements of coronal mass ejections heading for Earth

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