Fluxgate Magnetometer (FGM) P.I.: A. Balogh, Imperial College. Each spacecraft carries two 3-axes fluxgate sensors on a 5 m boom. The magnetometers will measure the magnetic field in the near Earth environment. The obvious uses of the four spacecraft simultaneous measurements are to (1) study the structure of the magnetopause and the bow shock, (2) infer current density in various regions of the magnetosphere (3) study propagation of plane waves in and around the magnetosphere and (4) study of small scale structures like FTEs and flux ropes.
Spatio-Temporal Analysis of Field Fluctuations (STAFF) P.I. N. Cornileau-Wehrlin, Center de Recherche en Physique de l'Environnement Terrestre et Planetaire, Paris. Uses a 3-axes search coil sensor mounted on a 5m boom to study magnetic field waveform up to 4 kHz
Electric Field and Waves (EFW) P.I.: G. Gustafsson, Swedish Inst. of Space Physics, Uppsals. To study temporal and spatial variations in the vector electric field in the range of zero to 100 kHz frequencies. The instrument uses two pairs of wire booms each 100 m long to measure potential differences with a sensitivity of 50 nV/m (Hz)^1/2.
Waves of Higher Frequency and Sounder for Probing of Density by Relaxation (WHISPER) P.I.: P.M.Eecreau, Laboratoire de Physique et Chimie de l'Environnement, Orleans. A transmitter/receiver pair that in the active mode emits short pulses to stimulate plasma resonaces. After transmission the receiver listens for plasma echoes in a narrow frequency range. By rapid switching between the transmit and recieve modes the receiver scans the frequency range between 4-80 kHz. In the passive mode the reciever uses filter banks to record natural plasma waves up to 400 kHz.
Wide Band Data (WBD) P.I. D. A. Gurnett, Univ. of Iowa. Using sensors of the EFW experiment wave form up to 100 kHz are recorded with variable center frequency. Only two of the four spacecraft have this experiment.
Digital Wave Processor (DWP) P.I.: L. J. C. Woolliscroft, Univ. Of Sheffield. By using a CMOS multiprocessor unit, DWP performs event selection (triggering), model control, data/compaction/compression and the resonance frequency identification for the Whisper experiment.
Electron Drift Instrument (EDI) P.I. G. Paschmann, MPI fur extraterrestrische Physik, Garching. Uses two electron guns to emit electrons which are received back at the spacecraft to derive the ambient electric field. In case of strong magnetic field, the displacememt of the gyrating electron over one gyration is measured by a triangulation method. At smaller magnetic field value, two beams are emitted into opposite direction and the time of flight is measured. This way electric field measurements at < 100 Hz is made with an accuracy of 0.1-10 mV/m.
Cluster Ion Spectrometry (CIS) H. Reme, Centre d'Etude Spatial des Rayonnement, Toulouse. Employs two sensors. CODIF the first sensor is used to obtain the full three-dimensional ion distribution of the major species with high time resolution and mass per charge plasma composition. Also uses a retarding potentail analyzer for the low-energy ions. The second sensor (HIA) is designed for the highly directional, beam like ion flows in the solar wind.
Plasma Electron and Current Analyser (PEACE) P.I.: A. D. Johnstone, Mullard Space Science Lab, Holmbury and St. Mary College, London. Low energy electrons (0-100 eV) are measured using a spherical electrostatic analyzer (LEEA) with a PI x 3.8 degree radial field of view. The higher energy electrons (0.1-30 keV) are measured with HEEA which is a toroidal electrostatic analyzer with a 2*PI X 4.6 degree field of view.
Research with Adapive Particle Imaging Detectors (RAPID) P.I. B. Wilken, MPI fur Aeronomie, Lindau/Harz. Uses two position-sensitive solid state detectors (Imaging Ion Mass Spectrometer (IIMS) and Imaging Electron Spectrometer (IES)) to measure the distribution functions of high energy ions (2-1500 keV/nuc) and electrons (20-400 keV).
Active Spacecraft Potential Control (ASPOC) P.I.: W. Riedler, Institut fur Weltraumforschung, Graz. Uses a liquid metal (indium) ion emitter to actively control spacecraft potential so measurement of cold plasma population can be made accurately.
UCLA contribution: Prof. Margaret Kivelson and Richard Elphic are co-investigators in the magnetic field experiment (MAG) on Cluster. Our institute provided the expertise in the magnetic cleanliness program of the mission. The UCLA team is also responsible for routine data reduction and processing and writing software for the inflight intra and inter calibration of the magnetometer tetrahedron.