Photoelectron Current Measurement in Low Earth Orbit Using a Lean Satellite, HORYU-IV

This study presents the development and implementation of a photoelectron current measurement system on-board HORYU-IV satellite to take on-orbit measurements from conductive and insulator surfaces. The measurement system aims at providing critical information on photoelectron yield of materials widely used onboard spacecraft. HORYU-IV is the fourth satellites of the HORYU series developed at Kyushu Institute of Technology and it was piggy-back launched on-board H-IIA F30 rocket at an altitude of 575 km on February 17, 2016 (JST). The measurement system mainly consists of current-voltage amplifier circuits for AU, Kapton® and black Kapton® samples with gains of 1x, 3x and 1x amplification, respectively. In this article, the analysis of the on-orbit results is presented. The on-orbit results show that a photoelectron current of 2.9nA and 3.1nA was measured from black Kapton® sample at respective elevations of 70.7° and 71.1°. These results respectively correspond to a current density of 14.0μA/m2 and 18.0μA/m2 at 71.1°. This study also presents various ground-based tests results performed to verify and validate the effectiveness of the photoelectron current measurement system developed for space applications.