MMS Fast Plasma Instrument

FPI summary plot in SPEDAS

SPEDAS provides command line and GUI access to the MMS FPI data.

Prior to using these data, please read the FPI Release Notes:

https://lasp.colorado.edu/mms/sdc/public/datasets/fpi/ (FPI Release Notes)

FPI Moments

For more complete examples, see the FPI crib sheets located in the /mms/examples/ folder.

Examples

Electron Moments Data

To load and plot the MMS1 FPI electron moments data on March 7, 2016: <syntaxhighlight lang="idl"> MMS> mms_load_fpi, datatype='des-moms', trange=['2016-03-07', '2016-03-08'], probe=1

MMS> tplot, 'mms1_des_numberdensity_fast'

MMS> tdegap, ['mms1_des_energyspectr_omni_fast', 'mms1_des_pitchangdist_avg'], /overwrite

MMS> tplot, ['mms1_des_energyspectr_omni_fast', 'mms1_des_pitchangdist_avg'] </syntaxhighlight>

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  MMS1 FPI electron density on March 7, 2016

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  MMS1 FPI electron energy spectra and pitch angle distribution on March 7, 2016

Ion Moments Data

To load and plot the ion density, along with the omni-directional spectra on March 7, 2016: <syntaxhighlight lang="idl"> MMS> mms_load_fpi, datatype='dis-moms', trange=['2016-03-07', '2016-03-08'], probe=1

MMS> tdegap, ['mms1_dis_numberdensity_fast', 'mms1_dis_energyspectr_omni_fast'], /overwrite

MMS> tplot, ['mms1_dis_numberdensity_fast', 'mms1_dis_energyspectr_omni_fast'] </syntaxhighlight>

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  MMS1 FPI ion density and energy spectra on March 7, 2016

FPI Distributions

SPEDAS can also be used to generate secondary data products (energy, gyrophase, PA spectra) from the FPI distribution functions.

Examples

Electron Distribution Data

Generate and plot the electron energy spectra and PAD from the FPI distribution functions:

<syntaxhighlight lang="idl"> MMS> mms_part_getspec, instrument='fpi', probe='1', species='e', data_rate='brst', level='l2', outputs=['energy', 'pa'], trange=['2015-10-16/13:02:30', '2015-10-16/13:07:30']

MMS> tdegap, '*_des_dist_brst_*', /overwrite ; be sure not to interpolate through data gaps

MMS> tplot, ['mms1_des_dist_brst_energy', 'mms1_des_dist_brst_pa']

</syntaxhighlight>

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  MMS1 FPI electron spectra and PAD on October 16, 2015

To generate angle-angle plots from the FPI electron distribution functions at a specific time:

<syntaxhighlight lang="idl"> MMS> mms_fpi_ang_ang, '2015-10-16/13:07:30', species='e', data_rate='brst'

</syntaxhighlight>

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Ion Distribution Data

Generate and plot the ion energy spectra and PAD from the FPI distribution functions:

<syntaxhighlight lang="idl"> MMS> mms_part_getspec, instrument='fpi', probe='1', species='i', data_rate='brst', level='l2', outputs=['energy', 'pa'], trange=['2015-10-16/13:02:30', '2015-10-16/13:07:30']

MMS> tdegap, '*_dis_dist_brst_*', /overwrite ; be sure not to interpolate through data gaps

MMS> tplot, ['mms1_dis_dist_brst_energy', 'mms1_dis_dist_brst_pa']

</syntaxhighlight>

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  MMS1 FPI ion spectra and PAD on October 16, 2015

To generate angle-angle plots from the FPI ion distribution functions at a specific time:

<syntaxhighlight lang="idl"> MMS> mms_fpi_ang_ang, '2015-10-16/13:07:30', species='i', data_rate='brst'

</syntaxhighlight>

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FPI 2D Slices

Examples

Basic 2D Slices

Load the FPI ion distribution data:

<syntaxhighlight lang="idl">

MMS> mms_load_fpi, data_rate='brst', datatype='dis-dist', probe=1, trange=['2015-10-16/13:06', '2015-10-16/13:07']

</syntaxhighlight>

Reformat the data for plotting using spd_slice2d:

<syntaxhighlight lang="idl">

MMS> dist = mms_get_dist('mms1_dis_dist_brst', trange=['2015-10-16/13:06', '2015-10-16/13:07'])

MMS> slice = spd_slice2d(dist, time='2015-10-16/13:06') ;3D interpolation

</syntaxhighlight>

Now plot the slice:

<syntaxhighlight lang="idl">

MMS> spd_slice2d_plot, slice

</syntaxhighlight>

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  MMS1 FPI ion 2D velocity distribution slice at 13:06UT on October 16, 2015

Visualizing 3D Distribution Functions

SPEDAS can also be used for visualizing MMS 3D distribution functions from FPI using the ISEE3D tool, developed by the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Japan.

Load data into tplot <syntaxhighlight lang="idl">

MMS> mms_load_fpi, probe=1, trange=['2015-10-20/05:56:30', '2015-10-20/05:56:34'], data_rate='brst', datatype='dis-dist'

</syntaxhighlight>

Load the data into standard structures <syntaxhighlight lang="idl">

MMS> dist = mms_get_fpi_dist('mms1_dis_dist_brst' , trange=['2015-10-20/05:56:30', '2015-10-20/05:56:34'])

MMS> data = spd_dist_to_hash(dist) ;convert structures to isee_3d data model

</syntaxhighlight>

Load the magnetic field (cyan vector) and velocity (yellow vector) support data <syntaxhighlight lang="idl">

MMS> mms_load_fgm, probe=1, trange=['2015-10-20/05:55:30', '2015-10-20/05:57:34'], level='l2'

MMS> mms_load_fpi, data_rate='brst', datatype='dis-moms', probe=1, trange=['2015-10-20/05:56:30', '2015-10-20/05:56:34']

</syntaxhighlight>

Once the GUI is opened, select PSD from Units menu <syntaxhighlight lang="idl">

MMS> isee_3d, data=data, trange=['2015-10-20/05:56:30', '2015-10-20/05:56:34'], bfield='mms1_fgm_b_gse_srvy_l2_bvec', velocity='mms1_dis_bulkv_dbcs_brst'

</syntaxhighlight>

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  MMS1 FPI ion 3D velocity distribution at 5:56:30UT on October 20, 2015