NSSDCA ID: 1998-041A-15
Mission Name: NozomiThe Extreme Ultraviolet Spectrometer (XUV) is part of the Plasma Spectrum Analyzer (PSA) experiment which also includes the electron and ion analyzers and the high energy particle instruments. The XUV is an X-ray ultraviolet scanner and will be used to observe interplanetary helium ions during cruise phase and make measurements of the abundance and distribution of helium gas and ion content in the upper atmosphere and ionosphere of Mars, which will be used to constrain the thermal history of the planet.
The XUV is mounted on the side panel of Nozomi facing downward and is thermally insulated from the rest of the spacecraft. It is designed to measure EUV emissions from the Sun scattered by helium atoms (the Helium I emission line, 58.4 nm) and helium ions (the Helium II emission line, 30.4 nm) and consists of a hood, a telescope, and a pre-amplifier with a high voltage supply unit. The telescope is made up of a Mo/Si multi-layer coated focusing mirror and microchannel plates (MCP). Incident light enters the hood and is reflected and focused by the 6.0 cm aperture mirror to the MCP, which has a 1.0 cm aperture. The focal length is 7.0 cm. The mirror preferentially reflects 30.4 nm EUV light and emissions above 50 nm wavelength. The light passes through two filters which attenuate unwanted wavelengths to the three stage MCP. The first stage is coated with CsI to enhance photon detection. A system of 4 anodes are used, two small anodes (1 mm radius with a field of view of 0.61 millisteradians) and two large anodes (2 mm radius, 2.5 millisteradians). A filter over one small and one large anode cuts out emissions over 40 nm so the anodes detect only 30.4 nm. The other pair of anodes detects both 30.4 and 58.4 nm emissions. The anode signals are amplified, digitized, and sent to telemetry. A 2 dimensional image is built up, one dimension provided by the spacecraft spin and one by the orbital motion. One or two 2-D images will be produced in this manner each orbit so the temporal resolution of the image is at this level.
Mass: 0.87 kg
Power (avg): 3.5 W
Questions and comments about this experiment can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Koujun Yamashita | Principal Investigator | Osaka University |