Suprathermal Mass Spectrometer (SMS)

Request for Users

Data and figures may be downloaded and used for scientific research and oral/poster presentations.
To request additional data or figures, please contact Prof. Andrew W. Yau.
    1. If you are using SMS data for publication, please Contact Prof. Andrew W. Yau to confirm the reliability of the data before submission of your publication.
    2. Send a reprint of your publication to the AKEBONO Project Office.
    3. Acknowledge use of the data as follows: The AKEBONO/SMS data were provided by Prof. Andrew W. Yau through DARTS at the Institute of Space and Astronautical Science (ISAS), Japan.

Information on SMS

SMS Instrument and Operation

The Akebono Suprathermal Mass Spectrometer (SMS) is a radio-frequency ion mass spectrometer. It is designed to measure the mass composition and velocity distribution (mass-per-charge, energy-per-charge and angular distribution in the spacecraft spin-plane) of thermal and suprathermal (0.1-4000 eV/q) ions in the ionosphere and magnetosphere. It consists of a retarding potential analyzer, a 3-stage modified Bennett ion mass spectrometer, and a micro-channel plate detector. It can sample ions at 256 mass steps over the 1-80 AMU/q mass range, and 256 retarding potential steps in the 0.1-25.6V range, and 16 suprathermal energy steps in the 100-4000 V range. It operates in a number of fast scan and mass scan operation modes.

For a detailed description of the SMS instrument and its operation, please see B. A. Whalen, J. R. Burrows, A. W. Yau, E. E. Budzinski, A. M. Pilon, I. Iwamoto, K. Marubashi, S. Watanabe, H. Mori, and E. Sagawa, The suprathermal ion mass spectrometer (SMS) onboard the EXOS-D satellite. J. Geomag. Geoelectr. 42, 511-536, 1990 and A. W. Yau, E. Drakou, M. J. Greffen, D. J. Knudsen, and E. Sagawa, Radio-frequency ion mass spectrometer measurements of thermal ion composition, velocity, and temperature: the EXOS-D Suprathermal Mass Spectrometer, Geophys. Monogr. Ser., 102, 307-312, 1998.

SMS Science Data Base (SDB)

Only fast scan data are available in the SDB. In its fast scan mode, SMS typically samples 4 major ion mass species (H+, He+, O+, and He++ or O++). In each 8-s spin period, it samples each ion species at 32 or 64 spin angles and 8 or 16 retarding potential or suprathermal energy steps.

SMS Summary Plots

The Summary Plots in the SMS SDB present 64-s averaged data (32-s averaged data where an orbit pass is less than 32 minutes), in the following format:
Panel a:
Spin angle versus time spectrogram of thermal H+ ion counts
Panel b:
Spin angle versus time spectrogram of thermal He+ ion counts
Panel c:
Spin angle versus time spectrogram of thermal O++ or He++ ion counts
Panel d:
Spin angle versus time spectrogram of thermal O+ ion counts
Panel e:
Retarding potential steps (histograms) and minimum ram angle
Panel f:
Spin angle versus time spectrogram of suprathermal H+ ion counts
Panel g:
Spin angle versus time spectrogram of suprathermal O+ ion counts
Panel h:
Suprathermal energy steps (histograms) and minimum pitch angle
In panels a-d and g-h:
  • The spin angle is defined with respect to the direction nearest to the local magnetic field, in degrees (-180 to 180). 0o ions are parallel to (or closest to) the magnetic field, i.e. downward in the northern and upward in the southern hemispheres. +/-180o ions are anti-parallel to (or farthest from) the magnetic field; +/-90o ions are perpendicular to it.
  • The curve denotes the spacecraft ram direction, i.e., the spin angle closest to the spacecraft velocity direction.
In panel d:
  • The color of the histogram denotes the instrument entrance aperture selected for the thermal ion measurements. Red: large aperture; yellow: medium aperture; green: small aperture.
  • The retarding potential, V, is in volts (0 - 25).
  • The minimum ram angle, r, is in degrees (0 - 90).
In panel h:
  • The suprathermal energy, E, is in volts (0 - 4000).
  • The minimum pitch angle, p, is in degrees (0 - 90).
Data Reliability Flag
The horizontal line below panel h is a data quality indicator. Green: data valid; yellow: data probably reliable but caution required in data interpretation; red: data may be unreliable - consult SMS Science Team before use; white (or black): data quality unspecified.
PI and Contact person
Instrumentation Reference Paper

Summary Plot, and SDB at specific date

0. Available data in each year

1. Please set "Year and Month".


2. Please select output type

Summary Plot SDB-data

Last Modified: 24 July 2013