Cluster II

The Composition and Distribution Function (CODIF) Analyzer

CODIF sensor. Particles can enter through the aperture all around the front end of the cylindrical section of the instrument.

CODIF measures the 3D distribution functions of the major ion species, H, He+, He++, and O+. It consists of a toroidal energy-per-charge (E/q) analyzer with a disk-shaped field of view, followed by a 20 kV post-acceleration into a time-of-flight (TOF) analysis section. The E/q range is 15 V to 40 kV. An optional retarding potential analyzer in the entrance aperture allows the energy range to be extended down to essentially zero volts. To accommodate the large dynamic range in ion fluxes, the instrument has split the 360 deg. FoV into two 180 deg. sections whose sensitivities differ by a factor of 100. Moments of the distribution of all 4 ion species are computed onboard and are available every spin, i.e., every 4 seconds. (You will find a flow chart of its principles of operation here.) The instrument is identical to the ESIC instrument on Equator-S.

Pictures of CODIF are available, from both before and after the explosion.

Link to: Cluster CIS Server (France)

To learn more, read the instrument description paper, or watch the Time of Flight Detector Movie