Data Description

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SPASE version 2.0.0

Numerical Data Product: THEMIS-A: Probe Electric Field Instrument and Search Coil Magnetometer Instrument, Digital Fields Board - digitally computed Filter Bank spectra and E12 peak and average in HF band.

Resource ID
spase://VMO/NumericalData/THEMIS/A/FBK/PT4S Get XML
Name
THEMIS-A: Probe Electric Field Instrument and Search Coil Magnetometer Instrument, Digital Fields Board - digitally computed Filter Bank spectra and E12 peak and average in HF band.
Description

The Filter Bank is part of the Digital fields board and provides band-pass filtering for EFI and SCM spectra as well as E12HF peak and average value calculations. The Filter Bank provides band-pass filtering for less computationally and power intensive spectra than the FFT would provide. The process is as follows: Signals are fed to the Filter Bank via a low-pass FIR filter with a cut-off frequency half that of the original signal maximum. The output is passed to the band-pass filters, is differenced from the original signal, then absolute value of the data is taken and averaged. The output from the low-pass filter is also sent to a second FIR filter with 2:1 decimation. This output is then fed back through the system. The process runs through 12 cascades for input at 8,192 samples/s and 13 for input at 16,384 samples/sec (EAC input only), reducing the signal and computing power by a factor 2 at each cascade. At each cascade a set of data is produced at a sampling frequency of 2^n from 2 Hz to the initial sampling frequency (frequency characteristics for each step are shown below in Table 1). The average from the Filter Bank is compressed to 8 bits with a pseudo-logarithmic encoder. The data is stored in sets of six frequency bins at 2.689 kHz, 572 Hz, 144.2 Hz, 36.2 Hz, 9.05 Hz, and 2.26 Hz. The average of the coupled E12HF signal and it's peak value are recorded over 62.5 ms windows (i.e. a 16 Hz sampling rate). Accumulation of values from signal 31.25 ms windows is performed externally. The analog signals fed into the FBK are E12DC and SCM1. Sensor and electronics design provided by UCB (J. W. Bonnell, F. S. Mozer), Digital Fields Board provided by LASP (R. Ergun), Search coil data provided by CETP (A. Roux).

Table 1: Frequency Properties.

Cascade | Frequency content of Input Signal | Low-pass Filter Cutoff Frequency | Freuency Content of Low-pass Output Signal | Filter Bank Frequency Band

0* 0 - 8 kHz 4 kHz 0 - 4 kHz 4 - 8 kHz 1 0 - 4 kHz 2 kHz 0 - 2 kHz 2 - 4 kHz 2 0 - 2 kHz 1 kHz 0 - 1 kHz 1 - 2 kHz 3 0 - 1 kHz 512 Hz 0 - 512 Hz 512 Hz - 1 kHz 4 0 - 512 Hz 256 Hz 0 - 256 Hz 256 - 512 Hz 5 0 - 256 Hz 128 Hz 0 - 128 Hz 128 - 256 Hz 6 0 - 128 Hz 64 Hz 0 - 64 Hz 64 - 128 Hz 7 0 - 64 Hz 32 Hz 0 - 32 Hz 32 - 64 Hz 8 0 - 32 Hz 16 Hz 0 - 16 Hz 16 - 32 Hz 9 0 - 16 Hz 8 Hz 0 - 8 Hz 8 - 16 Hz 10 0 - 8 Hz 4 Hz 0 - 4 Hz 4 - 8 Hz 11 0 - 4 Hz 2 Hz 0 - 2 Hz 2 - 4 Hz 12 0 - 2 Hz 1 Hz 0 - 1 Hz 1 - 2 Hz

*Only available for 16,384 Hz sampling.

Acknowledgement

NASA Contract NAS5-02099 and V. Angelopoulos for use of data from the THEMIS Mission. Specifically J. W. Bonnell, F. S. Mozer, Bob Ergun, and Alain Roux.

Contact
Role Person
1. Principal investigator Dr. Vassilis Angelopoulos Get XML
2. CoInvestigator John W. Bonnell Get XML
3. CoInvestigator Dr. Robert E. Ergun Get XML
4. CoInvestigator Prof. Forrest S. Mozer Get XML
5. CoInvestigator Dr. Alain Roux Get XML
Release date
2009-05-20 23:06:02
Repository
Name
CDAWeb Data Repository FTP Interface Get XML
Availability
Online
Access rights
Open
URL
CDAWeb FTP Access

NASA/GSFC CDAWeb ftp access to FBK data.

ASCII, CDF, and plots from CDAWeb

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

Format
CDF
Provider version
xxxx
Instruments
THEMIS-A Electric Field Instrument Get XML
THEMIS-A: Search Coil Magnetometer Get XML
Measurement type
Electric field
Magnetic field
Spectrum
Temporal description
Start date
2007-02-24 00:00:01
Relative stop date
7 days ago
Cadence
4 seconds
↑

Parameters

Parameter #1

Name
tha_fbh
Parameter key
tha_fb_hff
Description

Peak and average values from the coupled, high-frequency signal off opposing EFI booms 1 and 2. Booms 1 and 2 are situated in the spin plane of the spacecraft, boom 1 along the positive x-axis (SPG coordinates).

Caveats

hf_peak and hf_avg are the peak and average values of the output of the High-Frequency Filter, a broadband filter convering the 100- to 400-kHz band used for AKR detection

Units
V
Structure
Size
2
Elements
Index Name Valid min Valid max Fill value
1 FBK-A HF Filter Peak Voltage 0.0 1.0E10 NaN
2 FBK-A HF Filter Average Voltage 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #2

Name
tha_fbh_time
Parameter key
tha_fb_hff_time
Description

tha_fbh_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #3

Name
tha_fbh_compno
Parameter key
tha_fb_hff_compno
Description
Units
num
Structure
Size
2
Elements
Index Name Valid min Valid max Fill value
1 FBK-A HF Filter Peak Voltage 1 2 -32768
2 FBK-A HF Filter Average Voltage 1 2 -32768
Parameter type
Other

Parameter #4

Name
Calibrated Spectra
Parameter key
tha_fb_v1
Description

Spectrogram FBK potential, EFI sensor 1 in spacecraft spin plane along the positive x-axis(SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v1_1 0.0 1.0E10 NaN
2 tha_fb_v1_2 0.0 1.0E10 NaN
3 tha_fb_v1_3 0.0 1.0E10 NaN
4 tha_fb_v1_4 0.0 1.0E10 NaN
5 tha_fb_v1_5 0.0 1.0E10 NaN
6 tha_fb_v1_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #5

Name
tha_fb_v1_time
Parameter key
tha_fb_v1_time
Description

tha_fb_v1_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #6

Name
Calibrated Spectra
Parameter key
tha_fb_v2
Description

Spectrogram FBK potential, EFI sensor 2 in spacecraft spin plane along the negative x-axis (SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v2_1 0.0 1.0E10 NaN
2 tha_fb_v2_2 0.0 1.0E10 NaN
3 tha_fb_v2_3 0.0 1.0E10 NaN
4 tha_fb_v2_4 0.0 1.0E10 NaN
5 tha_fb_v2_5 0.0 1.0E10 NaN
6 tha_fb_v2_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #7

Name
tha_fb_v2_time
Parameter key
tha_fb_v2_time
Description

tha_fb_v2_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #8

Name
Calibrated Spectra
Parameter key
tha_fb_v3
Description

Spectrogram FBK potential, EFI sensor 3 in spacecraft spin plane along the positive y-axis (SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v3_1 0.0 1.0E10 NaN
2 tha_fb_v3_2 0.0 1.0E10 NaN
3 tha_fb_v3_3 0.0 1.0E10 NaN
4 tha_fb_v3_4 0.0 1.0E10 NaN
5 tha_fb_v3_5 0.0 1.0E10 NaN
6 tha_fb_v3_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #9

Name
tha_fb_v3_time
Parameter key
tha_fb_v3_time
Description

tha_fb_v3_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #10

Name
Calibrated Spectra
Parameter key
tha_fb_v4
Description

Spectrogram FBK potential, EFI sensor 4 in spacecraft spin plane along the negative y-axis (SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v4_1 0.0 1.0E10 NaN
2 tha_fb_v4_2 0.0 1.0E10 NaN
3 tha_fb_v4_3 0.0 1.0E10 NaN
4 tha_fb_v4_4 0.0 1.0E10 NaN
5 tha_fb_v4_5 0.0 1.0E10 NaN
6 tha_fb_v4_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #11

Name
tha_fb_v4_time
Parameter key
tha_fb_v4_time
Description

tha_fb_v4_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #12

Name
Calibrated Spectra
Parameter key
tha_fb_v5
Description

Spectrogram FBK potential, EFI sensor 5 located atop spacecraft along the spin axis (positive z-axis) (SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v5_1 0.0 1.0E10 NaN
2 tha_fb_v5_2 0.0 1.0E10 NaN
3 tha_fb_v5_3 0.0 1.0E10 NaN
4 tha_fb_v5_4 0.0 1.0E10 NaN
5 tha_fb_v5_5 0.0 1.0E10 NaN
6 tha_fb_v5_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #13

Name
tha_fb_v5_time
Parameter key
tha_fb_v5_time
Description

tha_fb_v5_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #14

Name
Calibrated Spectra
Parameter key
tha_fb_v6
Description

Spectrogram FBK potential, EFI sensor 6 located below the spacecraft along the spin axis (negative z-axis) (SPG coordinates).

Caveats

Average of absolute values.

Units
V
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_v6_1 0.0 1.0E10 NaN
2 tha_fb_v6_2 0.0 1.0E10 NaN
3 tha_fb_v6_3 0.0 1.0E10 NaN
4 tha_fb_v6_4 0.0 1.0E10 NaN
5 tha_fb_v6_5 0.0 1.0E10 NaN
6 tha_fb_v6_6 0.0 1.0E10 NaN
Quantity
Potential field

Parameter #15

Name
tha_fb_v6_time
Parameter key
tha_fb_v6_time
Description

tha_fb_v6_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #16

Name
Calibrated Spectra
Parameter key
tha_fb_edc12
Description

Spectrogram FBK coupled E field DC component, EFI sensors 1 and 2 in the spacecraft spin plane (sensor 1 along positive x-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3>V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_edc12_1 0.0 1.0E10 NaN
2 tha_fb_edc12_2 0.0 1.0E10 NaN
3 tha_fb_edc12_3 0.0 1.0E10 NaN
4 tha_fb_edc12_4 0.0 1.0E10 NaN
5 tha_fb_edc12_5 0.0 1.0E10 NaN
6 tha_fb_edc12_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #17

Name
tha_fb_edc12_time
Parameter key
tha_fb_edc12_time
Description

tha_fb_edc12_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #18

Name
Calibrated Spectra
Parameter key
tha_fb_edc34
Description

Spectrogram FBK coupled E field DC component, EFI sensors 3 and 4 in the spacecraft spin plane (sensor 3 along positive y-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3 >V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_edc34_1 0.0 1.0E10 NaN
2 tha_fb_edc34_2 0.0 1.0E10 NaN
3 tha_fb_edc34_3 0.0 1.0E10 NaN
4 tha_fb_edc34_4 0.0 1.0E10 NaN
5 tha_fb_edc34_5 0.0 1.0E10 NaN
6 tha_fb_edc34_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #19

Name
tha_fb_edc34_time
Parameter key
tha_fb_edc34_time
Description

tha_fb_edc34_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #20

Name
Calibrated Spectra
Parameter key
tha_fb_edc56
Description

Spectrogram FBK coupled E field DC component, EFI sensors 5 and 6 (axial, sensor 5 along positve z-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3>V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_edc56_1 0.0 1.0E10 NaN
2 tha_fb_edc56_2 0.0 1.0E10 NaN
3 tha_fb_edc56_3 0.0 1.0E10 NaN
4 tha_fb_edc56_4 0.0 1.0E10 NaN
5 tha_fb_edc56_5 0.0 1.0E10 NaN
6 tha_fb_edc56_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #21

Name
tha_fb_edc56_time
Parameter key
tha_fb_edc56_time
Description

tha_fb_edc56_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #22

Name
Calibrated Spectra
Parameter key
tha_fb_scm1
Description

Spectrogram for FBK Search Coil Magnetometer (SCM) Axis 1.

Caveats

Average of absolute values. SCM axes are specific to the instrument.

Units
nT
Conversion to SI units
1e-9>T
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_scm1_1 0.0 1.0E10 NaN
2 tha_fb_scm1_2 0.0 1.0E10 NaN
3 tha_fb_scm1_3 0.0 1.0E10 NaN
4 tha_fb_scm1_4 0.0 1.0E10 NaN
5 tha_fb_scm1_5 0.0 1.0E10 NaN
6 tha_fb_scm1_6 0.0 1.0E10 NaN
Quantity
Magnetic field

Parameter #23

Name
tha_fb_scm1_time
Parameter key
tha_fb_scm1_time
Description

tha_fb_scm1_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #24

Name
Calibrated Spectra
Parameter key
tha_fb_scm2
Description

Spectrogram for FBK Search Coil Magnetometer (SCM) Axis 2.

Caveats

Average of absolute values. SCM axes are specific to the instrument.

Units
nT
Conversion to SI units
1e-9>T
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_scm2_1 0.0 1.0E10 NaN
2 tha_fb_scm2_2 0.0 1.0E10 NaN
3 tha_fb_scm2_3 0.0 1.0E10 NaN
4 tha_fb_scm2_4 0.0 1.0E10 NaN
5 tha_fb_scm2_5 0.0 1.0E10 NaN
6 tha_fb_scm2_6 0.0 1.0E10 NaN
Quantity
Magnetic field

Parameter #25

Name
tha_fb_scm2_time
Parameter key
tha_fb_scm2_time
Description

tha_fb_scm2_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #26

Name
Calibrated Spectra
Parameter key
tha_fb_scm3
Description

Spectrogram for FBK Search Coil Magnetometer (SCM) Axis 3.

Caveats

Average of absolute values. SCM axes are specific to the instrument.

Units
nT
Conversion to SI units
1e-9>T
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_scm3_1 0.0 1.0E10 NaN
2 tha_fb_scm3_2 0.0 1.0E10 NaN
3 tha_fb_scm3_3 0.0 1.0E10 NaN
4 tha_fb_scm3_4 0.0 1.0E10 NaN
5 tha_fb_scm3_5 0.0 1.0E10 NaN
6 tha_fb_scm3_6 0.0 1.0E10 NaN
Quantity
Magnetic field

Parameter #27

Name
tha_fb_scm3_time
Parameter key
tha_fb_scm3_time
Description

tha_fb_scm3_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #28

Name
Calibrated Spectra
Parameter key
tha_fb_eac12
Description

FBK spectrogram for coupled E field AC component, EFI sensors 1 and 2 (spin plane, sensor 1 along positve x-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3>V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_eac12_1 0.0 1.0E10 NaN
2 tha_fb_eac12_2 0.0 1.0E10 NaN
3 tha_fb_eac12_3 0.0 1.0E10 NaN
4 tha_fb_eac12_4 0.0 1.0E10 NaN
5 tha_fb_eac12_5 0.0 1.0E10 NaN
6 tha_fb_eac12_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #29

Name
tha_fb_eac12_time
Parameter key
tha_fb_eac12_t ime
Description

tha_fb_eac12_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #30

Name
Calibrated Spectra
Parameter key
tha_fb_eac34
Description

FBK spectrogram for coupled E field AC component, EFI sensors 3 and 4 (spin plane, sensor 3 along positive y-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3>V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_eac34_1 0.0 1.0E10 NaN
2 tha_fb_eac34_2 0.0 1.0E10 NaN
3 tha_fb_eac34_3 0.0 1.0E10 NaN
4 tha_fb_eac34_4 0.0 1.0E10 NaN
5 tha_fb_eac34_5 0.0 1.0E10 NaN
6 tha_fb_eac34_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #31

Name
tha_fb_eac34_time
Parameter key
tha_fb_eac34_time
Description

tha_fb_eac34_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #32

Name
Calibrated Spectra
Parameter key
tha_fb_eac56
Description

FBK spectrogram for coupled E field AC component, EFI sensors 5 and 6 (axial, sensor 5 along positive z-axis, SPG coordinates).

Caveats

Average of absolute values.

Units
mV/m
Conversion to SI units
1e-3>V/m
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_eac56_1 0.0 1.0E10 NaN
2 tha_fb_eac56_2 0.0 1.0E10 NaN
3 tha_fb_eac56_3 0.0 1.0E10 NaN
4 tha_fb_eac56_4 0.0 1.0E10 NaN
5 tha_fb_eac56_5 0.0 1.0E10 NaN
6 tha_fb_eac56_6 0.0 1.0E10 NaN
Quantity
Electric field

Parameter #33

Name
tha_fb_eac56_time
Parameter key
tha_fb_eac56_time
Description

tha_fb_eac56_time, UTC, in seconds since 01-Jan-1970 00:00:00

Caveats

Not including leap seconds

Units
sec
Valid minimum
0.0
Valid maximum
5.0E9
Fill value
NaN
Parameter type
Temporal

Parameter #34

Name
tha_fb_yaxis
Parameter key
tha_fb_yaxis
Description

tha_fb_yaxis

Units
Hz
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fb_yaxis_1 0.0 10000.0 NaN
2 tha_fb_yaxis_2 0.0 10000.0 NaN
3 tha_fb_yaxis_3 0.0 10000.0 NaN
4 tha_fb_yaxis_4 0.0 10000.0 NaN
5 tha_fb_yaxis_5 0.0 10000.0 NaN
6 tha_fb_yaxis_6 0.0 10000.0 NaN
Parameter type
Temporal

Parameter #35

Name
tha_fbk_fstart
Parameter key
tha_fbk_fstart
Description

tha_fbk_fstart

Units
Hz
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fbk_fstart_1 0.0 1000000.0 NaN
2 tha_fbk_fstart_2 0.0 1000000.0 NaN
3 tha_fbk_fstart_3 0.0 1000000.0 NaN
4 tha_fbk_fstart_4 0.0 1000000.0 NaN
5 tha_fbk_fstart_5 0.0 1000000.0 NaN
6 tha_fbk_fstart_6 0.0 1000000.0 NaN
Parameter type
Temporal

Parameter #36

Name
tha_fbk_fband
Parameter key
tha_fbk_fband
Description

Graph Y-Axis, Frequency

Units
Hz
Structure
Size
6
Elements
Index Name Valid min Valid max Fill value
1 tha_fbk_fband_1 0.0 1000000.0 NaN
2 tha_fbk_fband_2 0.0 1000000.0 NaN
3 tha_fbk_fband_3 0.0 1000000.0 NaN
4 tha_fbk_fband_4 0.0 1000000.0 NaN
5 tha_fbk_fband_5 0.0 1000000.0 NaN
6 tha_fbk_fband_6 0.0 1000000.0 NaN
Parameter type
Temporal
↑

SPASE version 2.0.0

Instrument: THEMIS-A Electric Field Instrument

Instrument ID
spase://SMWG/Instrument/THEMIS/A/EFI Get XML
Name
THEMIS-A Electric Field Instrument
Alternate name
THEMIS-A EFI
Description

The Electric Field Instrument (EFI) on the THEMIS spacecraft measures the three components of the ambient vector electric field. Measurements are performed using four wire spin plane booms and two rigid axial booms. Waveform measurements cover DC up to 4 kHz (with AC-coupled differential measurements from ~10 Hz up to 8 kHz), with on-board spectral measurements covering the same ranges, as well as providing an estimate of integrated power in the 100- to 400-kHz band. On-board spin-fit E-field estimates are also provided for both the spin plane and axial measurements. On-board estimates of the spacecraft floating potential are also produced for use in particle moment calculations and burst trigger evaluations. Both individual (Vn, n=1..6) and differential (Emn = Vm – Vn, m,n = [(1,2), (3,4), (5,6)]) sensor potentials are measured. Booms 1 & 2 are in the spin plane and have a length from tip to tip of 49.6 meters. Booms 3 & 4 are in the spin plane and have a length from tip to tip of 40.4 meters. Booms 5 & 6 are the axial booms and have a length from tip to tip of 5.63 meters. The differential sensor potentials are used to estimate the ambient vector E-field. The individual sensor potentials are used to verify proper sensor operation, estimate the spacecraft floating potential, and measure the ambient plasma density with high (sub-spin-period) time resolution. Ground based electric field magnitude and direction measurements are provided with the Z component, with the Z component removed, and with the Z component estimated using the E.B=0 equality. The data are provided in DSL (despun spacecraft L-Z vector), GSM, and GSE coordinates.

Additional information
THEMIS-A Electric Fields Instrument

Instrument description from NSSDC database

Acknowledgement

NASA contract NAS5-02099 and V. Angelopoulos for use of data from the THEMIS Mission. Specifically: J. W. Bonnell and F. S. Mozer for use of EFI data.

Contact
Role Person
1. Principal investigator Dr. Vassilis Angelopoulos Get XML
2. CoInvestigator John W. Bonnell Get XML
3. CoInvestigator Prof. Forrest S. Mozer Get XML
Release date
2009-05-20 21:10:04
Prior ID
spase://SMWG/Instrument/THEMIS-A/EFI
Instrument type
Antenna
Double Sphere
Investigation name
THEMIS Electric Fields Instrument
Observatory
THEMIS-A Get XML
Caveats

Measurements on the axial booms (5 & 6) may have large errors due to their proximity to the spacecraft (the axial booms are much shorter than other booms). The spin plane booms for THEMIS A were not deployed until January 14, 2008 at 1700 UT, any EFI measurements before this date should not be used.

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SPASE version 2.0.0

Instrument: THEMIS-A: Search Coil Magnetometer

Instrument ID
spase://SMWG/Instrument/THEMIS/A/SCM Get XML
Name
THEMIS-A: Search Coil Magnetometer
Alternate name
THEMIS-A SCM
Description

THEMIS-A Search Coil Magnetometer for measuring three dimensional changes in magnetic flux between 0.1 Hz and 4 kHz; the range extending to 8 kHz under certain conditions. The instrument is mounted on a ridged, retractable boom one meter in length extending from the top corner of the spacecraft (positive y-axis, negative x-axis in SPG coordinates). The SCM boom deploys at an angle of -167.9 degrees from the x-axis (SPG) and 10.1 degrees above the spin plane. Two of the probe's sensors are aligned within the spin plane of the spacecraft, with the B_x component 12.1 degrees from the SPG x-axis, the third being parallel to the spin axis completing a right handed orthogonal system. The three sensors are composed of two windings surrounding a core with a high magnetic permeability. The main winding, used for detection, consists of 51600 turns; the secondary winding introduces a flux feedback to damped the frequency response of the sensor and keep it independent of temperature variation. Multi-Layer Insulation keeps the probe thermally insulated while electrostatic shielding reduces its sensitivity to electric fields. Low noise at slower frewencies allows for sufficient overlap with Fluxgate Magnetomer (FGM) measurements (noise less than 0.76 pT/sqrt(Hz) at 10 Hz). Data from the SCM is passed through three pre-amplifiers, one for each sensor component, before going on to the DFB and IDPU for processing and digitization. Survey modes for the SCM are listed below in Table 1.

Table 1: SCM Telemetry Modes.

Filter Bank (fbk)*: Mean signal value over 6 frequency bands (4-2 kHz, 1-0.5 kHz, 256-128 Hz, 64-32 Hz, 16-8 Hz, 4-2 Hz); sampling rate of 1/16 to 8 S/s. Fast Survey (scf): Waveform data for the 3 SCM components; sampling rate between 2 and 256 S/s, nominal value is 8. Particle Burst (scp): Waveform data nominally at 128 S/s. Wave Burst (scw): Waveform data nominally at 8192 S/s. Particle Burst Spectra (ffp)**: Compressed FFT spectra in 16, 32, or 64 frequency bins; sampling between 1/4 to 8 S/s. Wave Burst Spectra (ffw)**: Compressed FFT spectra in 16, 32, or 64 frequency bins; sampling between 1/4 to 8 S/s.

*Only two available inputs between all 3 SCM and 12 EFI data signals. **Only four available inputs between 3 SCM and 16 other data signals.

Additional information
THEMIS Home Page

THEMIS Home Page.

THEMIS-A Spacecraft

Spacecraft description from NSSDC database

THEMIS-A Search Coil Magnetometer

Instrument (SCM) description from NSSDC database.

The Search Coil Magnetometer for THEMIS

A. Roux et. al. In depth description of the THEMIS SCM.

Acknowledgement

NASA contract NAS5-02099, V. Angelopoulos for use of data from the THEMIS Mission; also A. Roux and CETP for their work on the SCM.

Contact
Role Person
1. Principal investigator Dr. Vassilis Angelopoulos Get XML
2. CoInvestigator Dr. Alain Roux Get XML
Release date
2009-05-20 21:10:04
Instrument type
Magnetometer
Search Coil
Investigation name
THEMIS Search Coil Magnetometer
Observatory
THEMIS-A Get XML
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SPASE version 2.0.0

Observatory: THEMIS-A

Observatory ID
spase://SMWG/Observatory/THEMIS/A Get XML
Name
THEMIS-A
Alternate name
Explorer 85
2007-004A
MIDEX/THEMIS
THEMIS-P5
30580
Description

The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission is a five-satellite Explorer mission whose primary objective is to understand the onset and macroscale evolution of magnetospheric substorms. Most importantly, THEMIS will find out which magnetotail process is responsible for substorm onset: (a) a local disruption of the plasma sheet current; or, (b) that current's interaction with the rapid influx of plasma emanating from lobe flux annihilation at ~25Re. Three inner probes at ~10Re will monitor current disruption onset, while two outer probes, at 20 and 30Re respectively, will remotely monitor plasma acceleration due to lobe flux dissipation. The five small satellites were launched together on a Delta II rocket and they carry identical sets of instruments including an electric field instrument (EFI), a flux gate magnetometer (FGM), a search coil magnetometer (SCM), a electro-static analyzer, and solid state telescopes (SST). The mission consists of several phases. In the first phase, the spacecraft will all orbit as a tight cluster in the same orbital plane with apogee at 15.4 Earth radii (RE). In the second phase, also called the Dawn Phase, the satellites will be placed in their orbits and during this time their apogees will be on the dawn side of the magnetosphere. During the third phase (also known as the Tail Science Phase) the apogees will be in the magnetotail. The fourth phase is called the Dusk Phase or Radiation Belt Science Phase, with all apogees on the dusk side. In the fifth and final phase, the apogees will shift to the sunward side (Dayside Science Phase).

All five satellites will have similar perigee altitudes (1.16-1.5 Re) but varying apogee altitudes (P1: ~30 RE, P2: ~20 RE, P3 & P4: ~12 RE, P5: ~10RE) with corresponding orbital periods of ~4, 2, and 1 days, respectively. This results in multi-point magnetic conjunctions. Every four days the satellites will line up along the Earth's magnetic tail with magnetic foot points in the North American sector, allowing the tracking of disturbances through different geospace regions from tail to ground.

The satellite data will be combined with observations of the aurora from a network of 20 ground observatories (all sky imagers, magnetometers) across the North American continent. In addition to its primary goal, THEMIS will answer critical questions in radiation belt physics and solar wind - magnetosphere energy coupling. THEMIS is complementary to MMS in terms of the temporal and spatial scales of the phenomena observed by these two constellation missions. THEMIS's focus is macroscale, whereas MMS will observe micro/meso scale features.

Additional information
Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission

THEMIS Mission Homepage

Information on Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission

NSSDC Master Catalog information on the THEMIS Mission

Acknowledgement

National Aeronautics and Space Administration/United States

Contact
Role Person
1. Principal investigator Dr. Vassilis Angelopoulos Get XML
2. Project scientist Dr. David G. Sibeck Get XML
Release date
2009-05-20 20:00:12
Prior ID
spase://SMWG/Observatory/THEMIS-A
Observatory group
THEMIS
Location
Region
Earth.Magnetosheath
Earth.Magnetosphere.Magnetotail
Earth.Magnetosphere.Main
Heliosphere.NearEarth
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Person: Dr. Vassilis Angelopoulos

Name
Dr. Vassilis Angelopoulos
Organization
University of California, Los Angeles
Email
vassilis@igpp.ucla.edu
vassilis@ssl.berkeley.edu
Phone
+1-310-794-7090
+1-510-643-1871
Person ID
spase://SMWG/Person/Vassilis.Angelopoulos Get XML
Release date
2008-03-11 19:28:45
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SPASE version 2.0.0

Person: John W. Bonnell

Name
John W. Bonnell
Organization
University of California, Berkeley
Address
University of California, Berkeley Space Sciences Lab 7 Gauss Way Berkeley, CA 94720-7450, Annex 7
Email
jbonnell@ssl.berkeley.edu
Phone
510-642-0852
Person ID
spase://SMWG/Person/John.W.Bonnell Get XML
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SPASE version 2.0.0

Person: Dr. Robert E. Ergun

Name
Dr. Robert E. Ergun
Organization
University of Colorado
Person ID
spase://SMWG/Person/Robert.E.Ergun Get XML
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SPASE version 2.0.0

Person: Prof. Forrest S. Mozer

Name
Prof. Forrest S. Mozer
Organization
University of California, Berkeley
Address
Room 306 Space Science Laboratory University of California, Berkeley Berkeley CA 94720
Email
mozer@sunspot.ssl.berkeley.edu
Phone
+1-510-642-0549
Person ID
spase://SMWG/Person/Forrest.S.Mozer Get XML
Release date
2008-08-26 18:43:16
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SPASE version 2.0.0

Person: Dr. Alain Roux

Name
Dr. Alain Roux
Organization
CNRS Centre de Recherches en Physique de L Environ
Person ID
spase://SMWG/Person/Alain.Roux Get XML
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SPASE version 2.0.0

Person: Dr. Robert E. McGuire

Name
Dr. Robert E. McGuire
Organization
NASA Goddard Space Flight Center
Address
Code 672, Greenbelt, MD 20771, USA
Email
mcguire@mail630.gsfc.nasa.gov
Phone
1-301-286-7794
Person ID
spase://SMWG/Person/Robert.E.McGuire Get XML
Release date
2007-05-30 15:25:24
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SPASE version 2.0.0

Person: Dr. David G. Sibeck

Name
Dr. David G. Sibeck
Organization
NASA/GSFC, Code 672
Person ID
spase://SMWG/Person/David.G.Sibeck Get XML
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SPASE version 1.2.0

Repository: CDAWeb Data Repository FTP Interface

Repository ID
spase://SMWG/Repository/NASA/GSFC/SPDF/CDAWeb Get XML
Name
CDAWeb Data Repository FTP Interface
Description

Coordinated Data Analysis Web (CDAWeb) supports not only interactive plotting of variables from multiple instruments on multiple investigations simultaneously on arbitrary, user-defined time-scales. It also supports data retrieval in various formats using its interactive web interface or ftp service.

Additional information
CDAWeb Home Page

Coordinated Data Analysis Web (CDAWeb) home page at Space Physics Data Facility of the NASA Goddard Space Flight Center.

Contact
Role Person
1. Project scientist Dr. Robert E. McGuire Get XML
Release date
2008-08-26 21:14:34
Prior ID
spase://VMO/Repository/CDAWeb
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