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MMS 2 Electron Drift Instrument (EDI) Ambient Electron Flux, Projection Method 1 (PM1), Level 2, Quick-Look Survey

ResourceID
spase://NASA/NumericalData/MMS/2/FIELDS/EDI/Survey/Level2/ElectronFluxAmbient/ProjectionMethod1/PT0.03125S

Description

Electron Drift Instrument (EDI) Ambient Survey, Level 2, 0.03125 s Data. (32 samples/s)EDI has two scientific data acquisition modes, called electric field mode and ambient mode. In electric field mode, two coded electron beams are emitted such that they return to the detectors after one or more gyrations in the ambient magnetic and electric field. The firing directions and times-of-flight allow the derivation of the drift velocity and electric field. In ambient mode, the electron beams are not used. The detectors with their large geometric factors and their ability to adjust the field of view quickly allow continuous sampling of ambient electrons at a selected pitch angle and fixed but selectable energy. To find the beam directions that will hit the detector, EDI sweeps each beam in the plane perpendicular to B at a fixed angular rate of 0.22 °/ms until a signal has been acquired by the detector. Once signal has been acquired, the beams are swept back and forth to stay on target. Beam detection is not determined from the changes in the count-rates directly, but from the square of the beam counts divided by the background counts from ambient electrons, i.e., from the square of the instantaneous signal-to-noise ratio (SNR). This quantity is computed from data provided by the correlator in the Gun-Detector Electronics that also generates the coding pattern imposed on the outgoing beams. If the squared SNR ratio exceeds a threshold, this is taken as evidence that the beam is returning to the detector. The thresholds for SNR are chosen dependent on background fluxes. They represent a compromise between getting false hits (induced by strong variations in background electron fluxes) and missing true beam hits. The basic software loop that controls EDI operations is executed every 2 ms. As the times when the beams hit their detectors are neither synchronized with the telemetry nor equidistant, EDI data have no fixed time-resolution. Data are reported in telemetry slots. In Survey, using the standard packing mode 0, there are eight telemetry slots per second and Gyn Detector Unit (GDU). The last beam detected during the previous slot will be reported in the current slot. If no beam has been detected, the data quality will be set to zero. In Burst telemetry there are 128 slots per second and GDU. The data in each slot consists of information regarding the beam firing directions (stored in the form of analytic gun deflection voltages), times-of-flight (if successfully measured), quality indicators, time stamps of the beam hits, and some auxiliary correlator-related information. Whenever EDI is not in electron drift mode, it uses its ambient electron mode. The mode has the capability to sample at either 90 degrees pitch angle or at 0/180 degrees (field aligned), or to alternate between 90 degrees and field aligned with selectable dwell times. While all options have been demonstrated during the commissioning phase, only the field aligned mode has been used in the routine operations phase. The choices for energy are 250 eV, 500 eV, and 1 keV. The two detectors, which are facing opposite hemispheres, are looking strictly into opposite directions, so while one detector is looking along B the other is looking antiparallel to B (corresponding to pitch angles of 180 and 0 degrees, respectively). The two detectors switch roles every half spin of the spacecraft as the tip of the magnetic field vector spins outside the field of view of one detector and into the field of view of the other detector. Up until January 4, 2016 the anodes were chosen such that the magnetic field vector projected into the plane of the micro-channel plate entry surface was best aligned with the center of the four anodes ( that is, with the gap between the inner two of the four anodes). Data taken in this configuration are using the term "amb" in the data product names. In the burst data where four channels (corresponding to the four adjacent sensor anode pads) are sampled per GDU, the average (or sum) of the center two channels (channels 2 and 3) represents best the pitch angle of 0 degrees (or 180 degrees). The EDI instrument paper can be found at: http://link.springer.com/article/10.1007%2Fs11214-015-0182-7. The EDI instrument data products guide can be found at https://lasp.colorado.edu/mms/sdc/public/datasets/fields/.

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Version:2.3.2

NumericalData

ResourceID
spase://NASA/NumericalData/MMS/2/FIELDS/EDI/Survey/Level2/ElectronFluxAmbient/ProjectionMethod1/PT0.03125S
ResourceHeader
ResourceName
MMS 2 Electron Drift Instrument (EDI) Ambient Electron Flux, Projection Method 1 (PM1), Level 2, Quick-Look Survey
ReleaseDate
2021-04-27 15:38:11Z
Description

Electron Drift Instrument (EDI) Ambient Survey, Level 2, 0.03125 s Data. (32 samples/s)EDI has two scientific data acquisition modes, called electric field mode and ambient mode. In electric field mode, two coded electron beams are emitted such that they return to the detectors after one or more gyrations in the ambient magnetic and electric field. The firing directions and times-of-flight allow the derivation of the drift velocity and electric field. In ambient mode, the electron beams are not used. The detectors with their large geometric factors and their ability to adjust the field of view quickly allow continuous sampling of ambient electrons at a selected pitch angle and fixed but selectable energy. To find the beam directions that will hit the detector, EDI sweeps each beam in the plane perpendicular to B at a fixed angular rate of 0.22 °/ms until a signal has been acquired by the detector. Once signal has been acquired, the beams are swept back and forth to stay on target. Beam detection is not determined from the changes in the count-rates directly, but from the square of the beam counts divided by the background counts from ambient electrons, i.e., from the square of the instantaneous signal-to-noise ratio (SNR). This quantity is computed from data provided by the correlator in the Gun-Detector Electronics that also generates the coding pattern imposed on the outgoing beams. If the squared SNR ratio exceeds a threshold, this is taken as evidence that the beam is returning to the detector. The thresholds for SNR are chosen dependent on background fluxes. They represent a compromise between getting false hits (induced by strong variations in background electron fluxes) and missing true beam hits. The basic software loop that controls EDI operations is executed every 2 ms. As the times when the beams hit their detectors are neither synchronized with the telemetry nor equidistant, EDI data have no fixed time-resolution. Data are reported in telemetry slots. In Survey, using the standard packing mode 0, there are eight telemetry slots per second and Gyn Detector Unit (GDU). The last beam detected during the previous slot will be reported in the current slot. If no beam has been detected, the data quality will be set to zero. In Burst telemetry there are 128 slots per second and GDU. The data in each slot consists of information regarding the beam firing directions (stored in the form of analytic gun deflection voltages), times-of-flight (if successfully measured), quality indicators, time stamps of the beam hits, and some auxiliary correlator-related information. Whenever EDI is not in electron drift mode, it uses its ambient electron mode. The mode has the capability to sample at either 90 degrees pitch angle or at 0/180 degrees (field aligned), or to alternate between 90 degrees and field aligned with selectable dwell times. While all options have been demonstrated during the commissioning phase, only the field aligned mode has been used in the routine operations phase. The choices for energy are 250 eV, 500 eV, and 1 keV. The two detectors, which are facing opposite hemispheres, are looking strictly into opposite directions, so while one detector is looking along B the other is looking antiparallel to B (corresponding to pitch angles of 180 and 0 degrees, respectively). The two detectors switch roles every half spin of the spacecraft as the tip of the magnetic field vector spins outside the field of view of one detector and into the field of view of the other detector. Up until January 4, 2016 the anodes were chosen such that the magnetic field vector projected into the plane of the micro-channel plate entry surface was best aligned with the center of the four anodes ( that is, with the gap between the inner two of the four anodes). Data taken in this configuration are using the term "amb" in the data product names. In the burst data where four channels (corresponding to the four adjacent sensor anode pads) are sampled per GDU, the average (or sum) of the center two channels (channels 2 and 3) represents best the pitch angle of 0 degrees (or 180 degrees). The EDI instrument paper can be found at: http://link.springer.com/article/10.1007%2Fs11214-015-0182-7. The EDI instrument data products guide can be found at https://lasp.colorado.edu/mms/sdc/public/datasets/fields/.

Acknowledgement
J. Burch, R. Torbert, H. Vaith
Contacts
RolePerson
1.PrincipalInvestigatorspase://SMWG/Person/James.L.Burch
2.PrincipalInvestigatorspase://SMWG/Person/Roy.B.Torbert
3.PrincipalInvestigatorspase://SMWG/Person/Hans.E.Vaith
4.MetadataContactspase://SMWG/Person/Robert.E.McGuire
5.MetadataContactspase://SMWG/Person/Lee.Frost.Bargatze
InformationURL
Name
The Magnetospheric Multiscale (MMS) Mission home page at Goddard Space Flight Center (GSFC)
URL
Description

The Magnetospheric Multiscale (MMS) Mission Home Page hosted by the Goddard Space Flight Center (GSFC).

InformationURL
Name
Data Caveats and Current Release Notes at LASP MMS SDC
URL
Description

The Magnetospheric Multiscale (MMS) Mission home page hosted by the Laboratory of Atmospheric and Space Physics, Science Data Center (LASP, SDC) at the University of Colorado, Boulder.

InformationURL
Name
At UNH
URL
Description

The Magnetospheric Multiscale (MMS) FIELDS Instrument Suite home page. The web page is hosted by the University of New Hampshire (UNH).

PriorIDs
spase://VSPO/NumericalData/MMS/2/FIELDS/EDI/Survey/Level2/ElectronFluxAmbient/ProjectionMethod1/PT0.03125S
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
Description

In CDF via ftp from SPDF.

AccessURL
Name
HTTPS from SPDF
URL
Description

In CDF via http from SPDF.

AccessURL
Name
CDAWeb
URL
ProductKey
MMS2_EDI_SRVY_L2_AMB
Description

Access to ASCII, CDF, and plots via NASA/GSFC CDAWeb

Format
CDF
Encoding
None
Acknowledgement
J. Burch, R. Torbert, H. Vaith. Please acknowledge the data providers and CDAWeb when using these data.
AccessInformation
RepositoryID
Availability
Online
AccessRights
Open
AccessURL
Name
CDAWeb HAPI Server
URL
Style
HAPI
ProductKey
MMS2_EDI_SRVY_L2_AMB@0
ProductKey
MMS2_EDI_SRVY_L2_AMB@1
Description

Web Service to this product using the HAPI interface.

Format
CSV
Acknowledgement
J. Burch, R. Torbert, H. Vaith. Please acknowledge the data providers and CDAWeb when using these data.
ProcessingLevel
Calibrated
InstrumentIDs
MeasurementType
EnergeticParticles
TemporalDescription
TimeSpan
StartDate
2015-09-01 00:00:00.000
RelativeStopDate
-P2M
Cadence
PT0.03125S
ObservedRegion
Earth.Magnetosheath
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.Magnetosphere.Magnetotail
ObservedRegion
Earth.Magnetosphere.Main
ObservedRegion
Earth.Magnetosphere.RadiationBelt
ObservedRegion
Earth.NearSurface.EquatorialRegion
ObservedRegion
Earth.NearSurface.Plasmasphere
ObservedRegion
Heliosphere.NearEarth
Parameter #1
Name
Epoch Time, 0 degree Electrons
ParameterKey
epoch_pa0
Description

Epoch Time Tags for EDU 0 degree Pitch Angle Electron Count Data, Terrestrial Time 2000 (TT2000)

Cadence
PT0.03125S
Units
ns
UnitsConversion
1e-9>s
RenderingHints
AxisLabel
UT
ValueFormat
I16
ValidMin
2015-03-01T00:00:00.000000000
ValidMax
2015-03-01T00:00:00.000000000
FillValue
9999-12-31T23:59:59.999999999
Support
SupportQuantity
Temporal
Parameter #2
Name
Epoch Time, 180 degree Electrons
ParameterKey
epoch_pa180
Description

Epoch Time Tags for EDU 180 degree Pitch Angle Electron Count Data, Terrestrial Time 2000 (TT2000)

Cadence
PT0.03125S
Units
ns
UnitsConversion
1e-9>s
RenderingHints
AxisLabel
UT
ValueFormat
I16
ValidMin
2015-03-01T00:00:00.000000000
ValidMax
2015-03-01T00:00:00.000000000
FillValue
9999-12-31T23:59:59.999999999
Support
SupportQuantity
Temporal
Parameter #3
Name
Epoch Time Tag
ParameterKey
epoch_timetag
Description

Epoch Time Tags for EDU Support Data, Terrestrial Time 2000 (TT2000)

Cadence
PT0.03125S
Units
ns
UnitsConversion
1e-9>s
RenderingHints
AxisLabel
UT
ValueFormat
I16
ValidMin
2015-03-01T00:00:00.000000000
ValidMax
2015-03-01T00:00:00.000000000
FillValue
9999-12-31T23:59:59.999999999
Support
SupportQuantity
Temporal
Parameter #4
Name
GDU1 Beam Energy
Set
Time series defined by using: EPOCH_TIMETAG
ParameterKey
mms2_edi_energy_gdu1
Description

Gun Detector Unit 2 Beam Energy

Cadence
PT0.03125S
Units
eV
UnitsConversion
1.602e-19>J
RenderingHints
AxisLabel
Energy
ValueFormat
I4
ValidMin
0
ValidMax
1000
FillValue
65535
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Energy
Parameter #5
Name
GDU2 Beam Energy
Set
Time series defined by using: EPOCH_TIMETAG
ParameterKey
mms2_edi_energy_gdu2
Description

Gun Detector Unit 1 Beam Energy

Cadence
PT0.03125S
Units
eV
UnitsConversion
1.602e-19>J
RenderingHints
AxisLabel
Energy
ValueFormat
I4
ValidMin
0
ValidMax
1000
FillValue
65535
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Energy
Parameter #6
Name
GDU Identifier, 0 degree, Pitch Angle
Set
Time series defined by using: EPOCH_PA0
ParameterKey
mms2_edi_gdu_0
Description

Sorts 0 degree Flux Counts by Gun Detector Unit

Cadence
PT0.03125S
RenderingHints
ValueFormat
I1
ValidMin
1
ValidMax
2
FillValue
255
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Counts
Parameter #7
Name
GDU Identifier, 180 degree, Pitch Angle
Set
Time series defined by using: EPOCH_PA180
ParameterKey
mms2_edi_gdu_180
Description

Sorts 180 degree Flux Counts by Gun Detector Unit

Cadence
PT0.03125S
RenderingHints
ValueFormat
I1
ValidMin
1
ValidMax
2
FillValue
255
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Counts
Parameter #8
Name
Electron Counts, 0 degree Pitch Angle
Set
Time series defined by using: EPOCH_PA0
ParameterKey
mms2_edi_counts1_0
Description

Counts for Electrons with 0 degree Pitch Angles

Cadence
PT0.03125S
RenderingHints
DisplayType
TimeSeries
AxisLabel
counts
ValueFormat
I5
ValidMin
0
ValidMax
65534
FillValue
65535
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Counts
Parameter #9
Name
Electron Counts, 180 degree Pitch Angle
Set
Time series defined by using: EPOCH_PA180
ParameterKey
mms2_edi_counts1_180
Description

Counts for Electrons with 180 degree Pitch Angles

Cadence
PT0.03125S
RenderingHints
DisplayType
TimeSeries
AxisLabel
counts
ValueFormat
I5
ValidMin
0
ValidMax
65534
FillValue
65535
Particle
ParticleType
Electron
Qualifier
Scalar
ParticleQuantity
Counts
Parameter #10
Name
Pitch Angle for 0 degree Electrons
Set
Time series defined by using: EPOCH_PA0
ParameterKey
mms2_edi_pa1_0
Description

Pitch Angle of Counts 0 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
DisplayType
TimeSeries
AxisLabel
PA
ValueFormat
F7.2
ScaleType
LinearScale
ValidMin
0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
DirectionAngle.PolarAngle
ParticleQuantity
ArrivalDirection
Parameter #11
Name
Pitch Angle for 180 degree Electrons
Set
Time series defined by using: EPOCH_PA180
ParameterKey
mms2_edi_pa1_180
Description

Pitch Angle of Counts 180 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
DisplayType
TimeSeries
AxisLabel
PA
ValueFormat
F7.2
ScaleType
LinearScale
ValidMin
0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
DirectionAngle.PolarAngle
ParticleQuantity
ArrivalDirection
Parameter #12
Name
Delta Minus, 0 degree Pitch Angle
ParameterKey
pa1_0_delta_minus
Description

Lower-Bound on the Pitch Angle for 0 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
ValueFormat
F7.2
ValidMin
-180.0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
Uncertainty
ParticleQuantity
ArrivalDirection
Parameter #13
Name
Delta Minus, 180 degree Pitch Angle
ParameterKey
pa1_180_delta_minus
Description

Lower-Bound on the Pitch Angle for 180 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
ValueFormat
F7.2
ValidMin
-180.0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
Uncertainty
ParticleQuantity
ArrivalDirection
Parameter #14
Name
Delta Plus, 0 degree Pitch Angle
ParameterKey
pa1_0_delta_plus
Description

Upper-Bound on the Pitch Angle for 0 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
ValueFormat
F7.2
ValidMin
-180.0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
Uncertainty
ParticleQuantity
ArrivalDirection
Parameter #15
Name
Delta Plus, 180 degree Pitch Angle
ParameterKey
pa1_180_delta_plus
Description

Upper-Bound on the Pitch Angle for 180 degree Electrons

Cadence
PT0.03125S
Units
degree
UnitsConversion
0.0174532925>rad
RenderingHints
ValueFormat
F7.2
ValidMin
-180.0
ValidMax
180.0
FillValue
-1.0e+31
Particle
ParticleType
Electron
Qualifier
Uncertainty
ParticleQuantity
ArrivalDirection