The Digital Ion Drift Meter (DIDM), developed by Amptek, Bedford, MA USA, for AFRL, was launched on July 15, 2000 aboard the Challenging Minisatellite Payload (CHAMP) -- developed by the GeoForschungsZentrum, Potsdam, Germany -- into a 421 x 475 km polar orbit. All components and functions of DIDM are performing nominally except for two notable problems. The first was the immediate loss of one of the two nearly redundant sensors. The malfunctioning sensor passes all diagnostic tests and the problem has been attributed to a blockage of the aperture screen. The other problem has been an uneven gain evolution of the micro-channel-plate used for the ion detection. Although the sensor is still functional, the gain evolution has forced us to develop an in-space calibration procedure. This procedure is now complete and we now have reasonable DIDM results for selected periods of the mission, and will soon be extending the new procedure to the entire mission. The data includes ion density and temperature, in-track and cross-track ion drift, and electron temperature. It is important to note that the surviving sensor had the lower geometric factor of the two sensors. This low geometric factor was selected to guarantee that one sensor would not experience dead-time effects during periods of extreme high plasma density. As a result, the DIDM data will always suffer from statistical limitation regardless of calibration, and we can now characterize the performance as about 100 m/s at a density 10000 /cc. This presentation will explain in detail the instrument design, the laboratory and in-space calibration procedures, and the data processing scheme and formats.
AGU Spring Meeting Abstracts
- Pub Date:
- May 2002
- 2467 Plasma temperature and density;
- 2494 Instruments and techniques;
- 2411 Electric fields (2712);
- 2435 Ionospheric disturbances