Concept information
Preferred term
EFI
Definition
- EFI, also referred to as CEFI (Canadian Electric Field Instrument), is provided by Canada (CSA funding, design by the University of Calgary, with ComDev Ltd. of Cambridge, Ontario as instrument manufacturer). The CEFI sensor is based on SII (Suprathermal Ion Imager)-a Canadian particle detector design that has already proven its capability - to gather precise measurements of ion winds. The goal of the CEFI instrument is to characterize the electric field about the Earth by measuring the plasma density, drift, and acceleration at high resolution; also for plasma density mapping in conjunction with GPS.. CEFI derives its heritage from the CPA (Cold Plasma Analyzer) instrument on Freja, the Nozomi TPA instrument and the CUSP, JOULE and GEODESIC sounding rocket missions. The plasma ion measurements are derived from energy-angle distributions that are generated by two orthogonal 2D electrostatic analyzers on each satellite. The ion bulk flow velocity and temperature are related to the distribution moments by transfer functions whose form are determined from simulations of the analyzers. The electric field is determined from measurements of the ion velocity and the magnetic field. The main sources of error come from uncertainties in the instrument transfer functions, the sensor-to-plasma potential difference, particle Poission noise, galactic cosmic ray event, and detector gain variations. The CEFI instrument is comprised of three main parts: the SII (Suprathermal Ion ImagerI) sensors, the LP (Langmuir Probe) sensors, and the Electronics Assembly. The electronics assembly contains all of the electronics necessary to support power supply, sensor data acquisition, instrument control and communications with the spacecraft bus. The electronics assembly and SII sensors will be positioned on the ram face of each Swarm spacecraft along with the Langmuir probes positioned preferably on the ram and nadir faces of each spacecraft and connected to the electronics assembly with wire harnesses. The SII sensors are of CPA heritage; they are using a unique particle focusing scheme developed at the University of Calgary. Ions enter a narrow aperture slit and are then deflected by a pair of hemispherical grids that create a region having electric fields directed radially inward. Incoming low-energy positive ions are accelerated toward the center of the spherical system, whereas ions with larger kinetic energies travel farther toward the edge of the detector, creating an energy spectrum as a function of detector radius. Particles arriving from out of the plane of Figure 37 land at different azimuths on the image plane. The resulting image from each SII sensor is a 2D cut through the ion distribution function, from which one can calculate ion density, drift velocity (2D), temperature, and higher-order moments. The two SII sensor head assemblies are oriented such that the aperture slits are oriented perpendicularly to each other, enabling 3D characterization of the ion distribution. Range of operational conditions: • Natural variability - Ion densities (108-10 m-3) - Ion and electron temperatures (0.1-0.5eV) - Ionospheric plasma flow (~200 m/s) • Active biasing of face plate • Passive biasing of material components associated with different work functions and contact potentials. When the charged particles strike the MCP Microchannel Plate) detector, the signal is amplified through secondary emission processes. The voltage applied across the MCP controls the gain of the device. In parts of the orbit where ion flux is high, the voltage applied to the front surface is reduced to limit the gain of the device and preserve its life. This gain adjustment is part of an automatic gain control realized through the use of a feedback loop using the CEFI instrument faceplate current as a control input. Where sufficient gain control cannot be achieved via the MCP voltage alone, an electrostatic shutter will gate the incoming ions with duty cycles ranging from 100% to well below 1%. A Langmuir Probe assembly is part of the CEFI device to provide measurement of electron density, electron temperature and spacecraft potential. The LP design is based on hardware flown on the Cluster and Rosetta missions of ESA and was developed by the Swedish Institute of Space Physics. The overall height of the LP sensor is 10 mm. The instrument electronics assembly includes the following electrical subsystems: • Instrument controller • Detector readout electronics • HVPS (High Voltage Power Supply) • LVPS (Low Voltage Power Supply). The primary function of the LVPS is to generate low voltages for other electronics within the Swarm CEFI instrument. • Langmuir probe assemblies. (en)
Broader concept
Change note
- 2018-07-11 08:02:08.0 [mmorahan] Insert Concept add broader relation (EFI [5e95a04f-e746-4b55-b0f0-76631bb197fe,367831] - Magnetic Field/Electric Field Instruments [449b7d65-85e6-43a5-b87b-1071dc9936b2,346983]);
- 2018-07-11 08:06:11.0 [mmorahan] insert AltLabel (id: null category: primary text: Electrical Field Instrument language code: en); insert Definition (id: null text: EFI, also referred to as CEFI (Canadian Electric Field Instrument), is provided by Canada (CSA funding, design by the University of Calgary, with ComDev Ltd. of Cambridge, Ontario as instrument manufacturer). The CEFI sensor is based on SII (Suprathermal Ion Imager)-a Canadian particle detector design that has already proven its capability - to gather precise measurements of ion winds. The goal of the CEFI instrument is to characterize the electric field about the Earth by measuring the plasma density, drift, and acceleration at high resolution; also for plasma density mapping in conjunction with GPS.. CEFI derives its heritage from the CPA (Cold Plasma Analyzer) instrument on Freja, the Nozomi TPA instrument and the CUSP, JOULE and GEODESIC sounding rocket missions. The plasma ion measurements are derived from energy-angle distributions that are generated by two orthogonal 2D electrostatic analyzers on each satellite. The ion bulk flow velocity and temperature are related to the distribution moments by transfer functions whose form are determined from simulations of the analyzers. The electric field is determined from measurements of the ion velocity and the magnetic field. The main sources of error come from uncertainties in the instrument transfer functions, the sensor-to-plasma potential difference, particle Poission noise, galactic cosmic ray event, and detector gain variations. The CEFI instrument is comprised of three main parts: the SII (Suprathermal Ion ImagerI) sensors, the LP (Langmuir Probe) sensors, and the Electronics Assembly. The electronics assembly contains all of the electronics necessary to support power supply, sensor data acquisition, instrument control and communications with the spacecraft bus. The electronics assembly and SII sensors will be positioned on the ram face of each Swarm spacecraft along with the Langmuir probes positioned preferably on the ram and nadir faces of each spacecraft and connected to the electronics assembly with wire harnesses. The SII sensors are of CPA heritage; they are using a unique particle focusing scheme developed at the University of Calgary. Ions enter a narrow aperture slit and are then deflected by a pair of hemispherical grids that create a region having electric fields directed radially inward. Incoming low-energy positive ions are accelerated toward the center of the spherical system, whereas ions with larger kinetic energies travel farther toward the edge of the detector, creating an energy spectrum as a function of detector radius. Particles arriving from out of the plane of Figure 37 land at different azimuths on the image plane. The resulting image from each SII sensor is a 2D cut through the ion distribution function, from which one can calculate ion density, drift velocity (2D), temperature, and higher-order moments. The two SII sensor head assemblies are oriented such that the aperture slits are oriented perpendicularly to each other, enabling 3D characterization of the ion distribution. Range of operational conditions: • Natural variability - Ion densities (108-10 m-3) - Ion and electron temperatures (0.1-0.5eV) - Ionospheric plasma flow (~200 m/s) • Active biasing of face plate • Passive biasing of material components associated with different work functions and contact potentials. When the charged particles strike the MCP Microchannel Plate) detector, the signal is amplified through secondary emission processes. The voltage applied across the MCP controls the gain of the device. In parts of the orbit where ion flux is high, the voltage applied to the front surface is reduced to limit the gain of the device and preserve its life. This gain adjustment is part of an automatic gain control realized through the use of a feedback loop using the CEFI instrument faceplate current as a control input. Where sufficient gain control cannot be achieved via the MCP voltage alone, an electrostatic shutter will gate the incoming ions with duty cycles ranging from 100% to well below 1%. A Langmuir Probe assembly is part of the CEFI device to provide measurement of electron density, electron temperature and spacecraft potential. The LP design is based on hardware flown on the Cluster and Rosetta missions of ESA and was developed by the Swedish Institute of Space Physics. The overall height of the LP sensor is 10 mm. The instrument electronics assembly includes the following electrical subsystems: • Instrument controller • Detector readout electronics • HVPS (High Voltage Power Supply) • LVPS (Low Voltage Power Supply). The primary function of the LVPS is to generate low voltages for other electronics within the Swarm CEFI instrument. • Langmuir probe assemblies. language code: en);
- 2019-02-22 17:21:15.0 [mmorahan] insert WeightedRelation (id: null related concept uuid: 054787a6-0c47-43af-a4ee-05c572dd1705 relationship type: null relationship value: null generated by: null); insert WeightedRelation (id: null related concept uuid: ab7f9a64-ca5d-4795-94ff-fd5367d39f9f relationship type: null relationship value: null generated by: null); insert WeightedRelation (id: null related concept uuid: 769a52d4-7db1-4b8e-8d39-6fee4e74d34f relationship type: null relationship value: null generated by: null);
URI
https://gcmd.earthdata.nasa.gov/kms/concept/5e95a04f-e746-4b55-b0f0-76631bb197fe
{{label}}
{{#each values }} {{! loop through ConceptPropertyValue objects }}
{{#if prefLabel }}
{{/if}}
{{/each}}
{{#if notation }}{{ notation }} {{/if}}{{ prefLabel }}
{{#ifDifferentLabelLang lang }} ({{ lang }}){{/ifDifferentLabelLang}}
{{#if vocabName }}
{{ vocabName }}
{{/if}}