Development of Plane-parallel Impact-ionization Dust Detectors with Large Aperture: A Candidate for Kibo Exposed Facility Payload

In-situ measurement of dust particles in space is important to study the origin or dust particles as well as space debris. Impact-ionization dust detector can supply mass and velocity information of impacting dust particles through the shape of charge signals of impact-generated plasma. Here we have tested plane-parallel type detectors with a target plate and an entrance grid. So far we tested three models with different target diameters: 5cm, 15cm, 30cm and one rectangular model with 20cm x 20cm aperture. Through calibration experiments using dust accelerators, we confirmed that the mass and velocity of impacted dust particles can be estimated from shapes of charge signals, as are previous impact-ionization type detectors. We confirmed that the charge signals do not depend largely on the position of the impact on the target.