Papers by Christophe Coillot
First results of the magnetospheric multiscale mission (MMS)
French repor
Flow velocity quantification
Broadband AC/DC hybrid magnetometer for space plasmas science
HAL (Le Centre pour la Communication Scientifique Directe), Apr 1, 2013
International audienceBroadband AC/DC hybrid magnetometer for space plasmas scienc
Magnetoresistive sensors for space instrumentation applications
HAL (Le Centre pour la Communication Scientifique Directe), Mar 29, 2011
International audienc
Module Éducation à la Transition Écologique (ETE) à l'université de Montpellier : retour d'expérience
HAL (Le Centre pour la Communication Scientifique Directe), Nov 9, 2021
International audienc
Radiation-hardened and low-noise ASIC amplifier designed for the highly sensitive ESA/JUICE induction magnetometer
International audienc
Recueil d'exercice sur les proprietes macroscopiques des materiaux magnetiques. Les applicati... more Recueil d'exercice sur les proprietes macroscopiques des materiaux magnetiques. Les applications concernent principalement les capteurs magnetiques (magnetoresistance, magneto-impedance, amplification magnetique).
TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference, 2007
We have selected stress-annealed nanocrystalline Fe-based ribbons for ferromagnetic/copper/ferrom... more We have selected stress-annealed nanocrystalline Fe-based ribbons for ferromagnetic/copper/ferromagnetic sensors exhibiting high magneto-impedance ratio. Longitudinal magneto-impedance ΔZ/Z sat reaches 400% at 60 kHz and longitudinal magneto-resistance ΔR/R sat increases up to 1300% around 200 kHz.
Performances of a high sensitive trilayer F/Cu/F GMI sensor
Sensors and Actuators A: Physical, 2008
ABSTRACT We have selected stress-annealed nanocrystalline FeSiBCuNb ribbons for trilayer ferromag... more ABSTRACT We have selected stress-annealed nanocrystalline FeSiBCuNb ribbons for trilayer ferromagnetic/copper/ferromagnetic sensors exhibiting high magneto-impedance (MI) ratio. Longitudinal MI δZ reaches 450% at 60kHz. Measurements of responses of the GMI sensor on the small amplitude ac fields displays sensitivity of 60V/T up to a few 100Hz. The noise equivalent magnetic induction is equal to 13nT/Hz+1/2, limited to the added noise from electronics.
A Low Frequency Receiver For The Solar Orbiter Mission
ABSTRACT The Low Frequency Receiver (LFR) is one of the main subsystems of the Radio and Plasma W... more ABSTRACT The Low Frequency Receiver (LFR) is one of the main subsystems of the Radio and Plasma Wave (RPW) experiment that we wish to submit in response to a possible Announcement of Opportunity for the Solar Orbiter payload. It will be connected to two different sensor units: an electric antenna unit and a magnetic search coil unit that will be optimized to perform both quasi-DC and high frequency measurements. The LFR is dedicated to analyse and process onboard the low frequency signals from a fraction of a Hertz up to ~10 kHz, covering in situ measurements of the electro- magnetic waves of the solar wind and extended corona. Due to the telemetry constraints different strategies for analysing and transmitting the data have to be defined, implying different onboard working modes. The design and the technological characteristics of the LFR are presented.
La pregnance de la degradation de l’environnement par l’homme doit nous amener a envisager de pro... more La pregnance de la degradation de l’environnement par l’homme doit nous amener a envisager de profonds changements de nos modes de vie, de mobilite, de production et de consommation pour aller vers une humanite plus harmonieuse avec l’environnement. La finalite de la technologie peut servir la resilience ecologique. Ainsi, l’avenement d’applications permettant d’envisager un covoiturage dynamique apporterait deux effets benefiques a la reduction de la pollution : l’un, lie a une decroissance de la consommation de carburant via l’optimisation du remplissage des vehicules et, l’autre, lie a la diminution du nombre d’automobiles en ville grâce a leur partage. Nous presentons l’embryon d’une application de carsharing reposant sur un algorithme genetique hermaphrodite (actuellement accessible sur github) en esperant pouvoir federer des developpeurs libres sur le projet
Induction sensors are used in a wide range of scientific and industrial applications. One way to ... more Induction sensors are used in a wide range of scientific and industrial applications. One way to improve these is rigorous modelling of the sensor combined with a low voltage and current input noise preamplifier aiming to optimize the whole induction magnetometer. In this paper, we explore another way, which consists in the use of original ferromagnetic core shapes of induction sensors, which bring substantial improvements. These new configurations are the cubic, orthogonal and coiled-core induction sensors. For each of them we give modelling elements and discuss their benefits and drawbacks with respect to a given noise-equivalent magnetic induction goal. Our discussion is supported by experimental results for the cubic and orthogonal configurations, while the coiled-core configuration remains open to experimental validation. The transposition of these induction sensor configurations to other magnetic sensors (fluxgate and giant magneto-impedance) is an exciting prospect of this work.
The dual-band search coil magnetometer : a new instrument for investigating wide band magnetic field fluctuations in space
ABSTRACT Due to their complementary performances search-coil and flux-gate magnetometers are comm... more ABSTRACT Due to their complementary performances search-coil and flux-gate magnetometers are commonly used in association onboard scientific spacecraft to measure magnetic field fluctuations. Flux-gates have an almost constant sensitivity from DC up to a few tens of Hz, meanwhile search-coils have a frequency dependent sensitivity, usually having a very flat minimum around a resonance frequency fixed by design. The sensitivities of these instruments cross over around 1Hz: search-coils have a much better sensitivity than flux-gates above this frequency, as low as a few fT/sqrt(Hz), and are usually designed to cover frequency bands extending over four to five decades. Frequency bands of ordinary search-coils can be chosen by design from typically [0.1Hz, 10kHz] to [10Hz, 100kHz]. We present the principle of a new instrument, the dual-band search-coil which has an effective frequency band from 0.1Hz to 1MHz. Two coils, one BF and one HF, share the same magnetic core owing to a mutual reducer which minimizes the effect of mutual impedance on each of the two transfer functions, BF and HF. An instrument of this type is part of the Plasma Wave Instrument onboard the Mercury Magnetospheric Orbiter of the ESA/JAXA BepiColombo mission.
Capteurs et dispositifs electroniques des magnetometres dedies a l'etude des ondes dans les p... more Capteurs et dispositifs electroniques des magnetometres dedies a l'etude des ondes dans les plasmas spatiaux.
Journal of Sensors and Sensor Systems, 2015
The performance of induction magnetometers, in terms of resolution, depends both on the induction... more The performance of induction magnetometers, in terms of resolution, depends both on the induction sensor and the electronic circuit. To investigate accurately the sensor noise sources, an induction sensor, made of a ferrite ferromagnetic core, is combined with a dedicated low voltage and current noise preamplifier, designed in CMOS 0.35 μm technology. A modelling of the contribution of the ferromagnetic core to the noise through the complex permeability formalism is performed. Its comparison with experimental measurements highlight another possible source for the dominating noise near the resonance.
Journal of Nondestructive Evaluation, 2011
Electromagnetic Non Destructive Evaluation (E-NDE) is often conducted by inducing eddy currents i... more Electromagnetic Non Destructive Evaluation (E-NDE) is often conducted by inducing eddy currents in the structure to be examined, if this is conducting. Existence of flaws is detected by difference between the response of defect-free structures and damaged ones. In the present paper, we model such processes in order to predict the feasibility of this evaluation and to facilitate the interpretation of the observation. An original method is to represent a crack by a current source producing a magnetic signal. We have applied it to the case of a defect with a standard shape. The experimental evidences for the validity of this method are given.
Journal of Sensors and Sensor Systems
Nuclear magnetic resonance imaging (MRI) has became an unavoidable medical tool in spite of its p... more Nuclear magnetic resonance imaging (MRI) has became an unavoidable medical tool in spite of its poor sensitivity. This fact motivates the efforts to enhance the nuclear magnetic resonance (NMR) probe performance. Thus, the nuclear spin excitation and detection, classically performed using radio-frequency coils, are required to be highly sensitive and homogeneous. The space harmonics suppression (SHS) method, already demonstrated to construct coil producing homogenous static magnetic field, is used in this work to design radiofrequency coils. The SHS method is used to determine the distribution of the electrical conductive wires which are organized in a saddle-coil-like configuration. The theoretical study of these SHS coils allows one to expect an enhancement of the signal-to-noise ratio with respect to saddle coil. Coils prototypes were constructed and tested to measure 1 H NMR signal at a low magnetic field (8 mT) and perform MRI acquired at a high magnetic field (3 T). The signal-to-noise ratios of these SHS coils are compared to the one of saddle coil and birdcage (in the 3 T case) of the same size under the same pulse sequence conditions demonstrating the performance enhancement allowed by the SHS coils.
Multi scale NMR investigations of two anatomically contrasted genotypes of sorghum under watered conditions and during drought stress
Magnetic Resonance in Chemistry
Journal of Sensors and Sensor Systems
Nuclear magnetic resonance (NMR) experiments are usually carried out at very high and homogenous ... more Nuclear magnetic resonance (NMR) experiments are usually carried out at very high and homogenous magnetic fields. However, portable systems have emerged in recent years at low fields, offering many advantages like easier maintenance and open design that permit us to imagine a variety of coil configurations in order to maximize the homogeneity of the static field B 0 and the radio-frequency field B 1. The wire winding distribution based on space harmonics suppression (SHS) of the cosine current density distribution offers new possibilities of producing homogenous static fields B 0. In this work, an extension of the SHS method, allowing homogeneity enhancement and flexibility of the coil design, is presented. The efficiency of the method is demonstrated through the construction of homogenous magnetic field coils dedicated to a very low magnetic field (8 mT) 1 H NMR spectrometer. The performance of these coils in terms of magnetic field intensity and homogeneity as well as self-heating behavior is compliant with in planta experiments for agronomic studies. 1 Introduction Global warming has increased the occurrence of stress in living plants, which forces them to adapt to the environmental conditions. This induces some modifications in growth and composition at physiological and biochemical levels (Osakabe et al., 2014). Due to the wide biodiversity of some plants, like sorghum, one needs to perform a study of the behavior for each species. The possibility of studying the local responses of plants to biotic and abiotic stress is limited since current anatomical and biochemical methods are destructive and do not allow us to investigate plants. Otherwise, nuclear magnetic resonance (NMR) offers the possibility of non-invasively and quantitatively measuring targeted nuclei like H, C, and N in plants (Van As and Schaafsma, 1984) and some of their physical properties like M 0 , T 1 , T 2 , diffusion and water velocity. The 1 H NMR signal is roughly quadratically dependent on the intensity of the magnetic field (Vo-Dinh, 2002). This consideration has historically oriented the NMR spectrometer design to higher mag-Published by Copernicus Publications on behalf of the AMA Association for Sensor Technology.
PloS one, 2018
The climate warming implies an increase of stress of plants (drought and torrential rainfall). Th... more The climate warming implies an increase of stress of plants (drought and torrential rainfall). The understanding of plant behavior, in this context, takes a major importance and sap flow measurement in plants remains a key issue for plant understanding. Magnetic Resonance Imaging (MRI) which is well known to be a powerful tool to access water quantity can be used to measure moving water. We describe a novel flow-MRI method which takes advantage of inflow slice sensitivity. The method involves the slice selectivity in the context of multi slice spin echo sequence. Two sequences such as a given slice is consecutively inflow and outflow sensitive are performed, offering the possiblility to perform slow flow sensitive imaging in a quite straigthforward way. The method potential is demonstrated by imaging both a slow flow measurement on a test bench (as low as 10 μm.s-1) and the Poiseuille's profile of xylemian sap flow velocity in the xylematic tissues of a tomato plant stem.
Uploads
Papers by Christophe Coillot