Development and calibration of major components for the STEREO/PLASTIC (plasma and suprathermal ion composition) instrument

The plasma and suprathermal ion composition (PLASTIC) instrument will measure kinetic properties and charge states of solar wind ions and suprathermal ions as part of the solar terrestrial relations observatory (STEREO) mission. Two identical instruments located on separate spacecraft will provide in situ plasma measurements at � 1 AU to study physical processes low in the corona and in the inner heliosphere. In conjunction with the other in situ and remote sensing instruments of STEREO, as well as existing nearEarth observatories, the PLASTIC instrument measurements will contribute to the understanding of the three-dimensional structure of the heliosphere, with particular focus on Coronal Mass Ejections. As the primary solar wind instrument aboard STEREO, PLASTIC will measure bulk solar wind plasma parameters (density, velocity, temperature, temperature anisotropy, and alpha/proton ratio) and the distribution functions and charge state distributions of major heavy solar wind ions (e.g., C, O, Ne, Mg, Si, Fe). The measurement apparatus includes an electrostatic deflection analyzer for energy per charge measurement (E/q), a time-of-flight section utilizing carbon foils and microchannel plate detectors for time of flight measurement (TOF), and solid-state detectors for energy measurement (E). The instrument will provide a large instantaneous field of view (in-ecliptic and out-of-ecliptic angles distinguished) with measurements taken at high time resolution (1–5 min) spanning an ion energy range of 0.25–87 keV/e. To accommodate a large range of particle fluxes, the PLASTIC Entrance System employs collection apertures with different geometric factors for the bulk solar wind (H � 96%, He � 4%) and for the heavy, less-abundant ions (<1%) and suprathermal ions. This paper focuses on the hardware development of major components for the PLASTIC instrument. The PLASTIC measurement principle is explained along with a presentation of the ion optic calibrations of the flight model Entrance Systems as well as calibrations of the microchannel plates and solid-state detectors. � 2005 Published by Elsevier Ltd on behalf of COSPAR.