The Solar Probe ANalyzer for Ions (SPAN-I) onboard NASA’s Parker Solar
Probe (PSP) spacecraft is an electrostatic analyzer with time-of-flight
capabilities that measures the ion composition and three dimensional
distribution function of the thermal corona and solar wind plasma.
SPAN-I measures the energy per charge of ions in the solar wind from 2
eV to 30 keV with a field-of-view of 247.5 • x 120 • while
simultaneously separating H + from He ++ to develop 3D distribution
functions of individual ion species. These observations, combined with
reduced distribution functions measured by the Sun-pointed Solar Probe
Cup (SPC), will help us further our understanding of the solar wind
acceleration and formation, the heating of the corona, and the
acceleration of particles in the inner heliosphere. This paper describes
the instrument hardware, including several innovative improvements over
previous time-of-flight (TOF) sensors, the data products generated by
the experiment, and the ground calibrations of the sensor.