The prime scientific objective of the CIS   (Cluster Ion Spectrometry) instrument is the study of the dynamics of magnetized plasma structures in and in the vicinity of the Earth's magnetosphere. The four Cluster spacecraft with relative separation distances that can be adjusted to spatial scales of the structures (a few hundred kilometers to several thousand kilometers) give for the first time the possibility to distinguish between spatial and temporal variations.

The CIS instrument has been designed to provide substantial contributions to:

•  the study of the solar wind/magnetosphere interaction,
•  the dynamics of the magnetosphere, including storms, substorms, and aurora,
•  physics of the magnetopause and the bow shock,
•  the polar cusps and the plasma sheet bounday layer dynamics,
•  the upstream foreshock and solar wind dynamics,
•  the magnetic reconnection and the field aligned current phenomena,
•  the study of low energy ionospheric population.

The CIS Experiment

The CIS instrument is an international collaboration lead by the Centre d'Etude Spatiale des Rayonnements ( CESR ) in Toulouse (Principle Investigator Prof  H. Rème).  The CIS instrument is a package of two sensors to cover a large energy range and to analyze the composition and dynamics of the magnetospheric ions. The sensors named

• CIS-1 or CODIF (composition distribution function) and
• CIS-2 or HIA (hot ion analyzer).

The CODIF instrument (left) is high resolution spectrometer that measures three-dimensional distribution functions of the principal ions in the magnetosphere (H+, He+, He++, O+). This instrument combines the selection of incoming ions according to their energy per charge by electrostatic deflection in a hemispherical analyzer with a subsequent time-of-flight analysis after a post acceleration of the incoming ions. The CODIF sensor includes also a Retarding Potential Analyzer (RPA) for the energy range 0 - 30 eV. The HIA instrument (right) is in principle like the CODIF instrument, but without the time-of-flight part, therefore it does not provide composition measurements. The HIA sensor is especially suited to measure the high particle flux of the solar wind (SW). There is a sophisticated data processing system (DPS) (middle) to control and to process the data of the sensors. This unit allows extensive onboard data processing. The main features and measured  parameters of the CIS instrument are shown in the table below.
For more details see

CODIF at Univ. New Hampshire

 
 

Instrument / Sensor

CODIF

HIA

Energy  Range  [keV/e]	~ 0 - 38	~ 0.005 - 32
Energy Distribution  (FWHM)	16 %	18 %
Time Resolution 2D  [ms]	125	62.5
Time Resolution 3D  [s]	4	4
Mass Range  [amu]	1 - 32	--
Angular Resolution  [°]	11.2 x 22.5	5.6 x 5.6
Full Field of View  [°]	8 x 360	8 x 360
Mass  [kg]	8.39	2.45
Power  [W]	6.96	2.82

Telemetry Rate

Normal  Mode 1	~   5.5 kbit/s
Burst Mode 1	~ 26.8 kbit/s

 

Hardware contribution from the MPAe

• Development and production of high voltage power supplies for extreme fast sweep voltages in electrostatic analyzers (sweep voltages of ~ 1ms) and high voltage power supplies for Channelplates which detect the ions.
• Development of a new pulse amplifier for count rates up to 5MHz. Subsequently the pulse amplifier were miniaturized at Amptek in Bedford, USA, and produced under Amptek A 121 as a space qualified version.
• The boards and the pulse amplifiers were produced for 4 Flight units and 1 Flight Spare unit

MPAe CIS team

Lead-Investigator:                             Dr  A. Korth                korth@linmpi.mpg.de       05556-979-430

Co-Investigator:                                 Dr  H. Rosenbauer

Engineers and Technicians:            B. Graeve,  G. Schlemm

Data analysis:                                      Dr  A. Korth                korth@linmpi.mpg.de       05556-979-430
                                                                 Dr  M. Fraenz             fraenz@linmpi.mpg.de     05556-979-441
                                                                 Dr  F. Frutos Alfaro  frutos@linmpi.mpg.de      05556-979-441 (until September 2002)
 

Project status
 

A detailed  CIS Instrument Description  is part of the  Annales Geophysicae Special Issue . See also the overview of the CIS instrument modes .

Instrument Performance

Both CIS sensors (CODIF and HIA) are fully operational on Cluster 1 and 3. The CIS instrument on Cluster 2 was switched off shortly after launch due to a failure in the instrument's low power supply. Further tests of CIS on Cluster 2 are planned at the end of nominal mission(2003).

The CIS HIA sensor on Cluster 4 was only partly operational for the first half of 2001 and switched off afterwards, further tests are planned at the end of nominal mission(2003).

The CIS CODIF sensor on Cluster 3 shows more rapid degradation than the other sensors - resulting in erroneous onboard moments for that sensor.  Ground calculated moments can take account of this effect.

In conclusion CIS CODIF data products can be used without restrictions from Cluster 1, 3 and 4 while CIS HIA products should only be taken from Cluster 1 and 3.

Data Status

CIS data processing is described in detail on the CESR Software Page . Essentially data are extracted at CESR from the Cluster CD-Roms (L0-data) and separated into CIS product files (L1-data). Auxiliary information (ephemeris and magnetic field data) are stored in the L3-data set. Using the current set of calibration files further products are calculated from L1-data:

Recalibrated onboard plasma moments (density, velocity, temperature and  pressure) calculated by CESR software are stored as L2-data.
Recalibrated 3D and onboard plasma moments (density, velocity, temperature and  pressure) calculated by IFSI software are stored in the L3-data set.

The MPAE gets L1 on CD-Roms with a delay of ~3 months. More recent data are copied from the CESR-server when needed. Data on the CESR-server have a delay of about 1 month. L2- and L3-data are regularly copied from CESR-server. L3-IFSI moments are produced at MPAE using the IFSI-software.

Data of other Cluster instruments are available from the  Cluster Science Data System (CSDS) . These are in the form of 4-sec Prime Parameters and 1-min Summary Parameters. At MPAE we regularly mirror that data-base using the  German Cluster Data Center .

Software Status

For scientific use of the data there are two independent software packages:

The CL package is an interactive data viewer based on IDL using a C-library for data-reading. It is being developed and maintained at CESR and recommended mainly for analysis of the HIA sensor data - though CODIF data can be displayed as well. The CL package is available to CIS team members at the  CESR Software Page .

The CCAT package is a command line oriented IDL-package based on the Tplot Package by Davin Larson . It allows extraction and display mainly of the CODIF sensor data and implements more refined moment calculations for that sensor. It also allows to extract the data as IDL data objects for easy manipulation of the data. CCAT was adapted for CIS-usage by Jim McFadden and Peter Schroeder of the SSL-Berkeley, and further developed by Chris Mouikis of Univ. of New Hampshire and Markus Fraenz of MPAE. Documentation for CCAT is currently in preparation. The package is also available on the CESR Software page.

A graphical user interface for Ccat has been developed in 2002.

Science Status

Major scientific topics for the Cluster mission were defined at the series of Cluster Workshops:

1st Cluster Workshop

2nd Cluster Workshop

3rd Cluster Workshop

At MPAE we are currently concentrating our work on following topics:

•      Oxygen beams in the inner magnetosphere and in the plasma sheet (Axel Korth).
•      Density gradient determination (Francisco Frutos, Markus Fraenz).
•      Solar wind magnetic holes (Markus Fraenz).

Related links

ESA

CESR

MPE

Univ. New Hampshire