Development of the Extreme Ultraviolet Spectrometer: EXCEED Go Murakami*, Kazuo Yoshioka, Atsushi Yamazaki, Tomoki Kimura Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Ichiro Yoshikawa, Kentaro Uji Department of Earth and Planetary Science, the University of Tokyo Fuminori Tsuchiya, Masato Kagitani Department of Geophysics, Graduate School of Science Tohoku University Kazunori Uemizu National Astronomical Observatory of Japan ABSTRACT The extreme ultraviolet (EUV) telescope EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) onboard the Japan's small satellite SPRINT-A will be launched in August 0. The EXCEED instrument will observe tenuous gases and plasmas around the planets in the solar system (e.g., Mercury, Venus, Mars, Jupiter, and Saturn). One of the primary observation targets is Jupiter, whose magnetospheric plasma dynamics is dominated by planetary rotation. In the EUV range, a number of emission lines originate from plasmas distributed in Jupiter's inner magnetosphere. The EXCEED instrument is designed to have a wavelength range of -4 nm with a spectral resolution of 0.4-.0 nm. The spectrograph slits have a field of view of 400 x 40 arc-seconds (maximum), and the attitude fluctuations are stabilized within arc-seconds. The optics of the instrument consists of a primary mirror with a diameter of 0cm, a laminar type grating, and an EUV detector using microchannel plates (MCPs). The surfaces of the primary mirror and the grating are coated with CVD-SiC. We have finished the final integration and ground calibration of the EXCEED instrument. We performed optical tests of EXCEED and measured the following performances.. Quantum efficiency of the detector: >0%. : 0. nm (0 slit) and.0 nm (60 slit). Spatial resolution: 6-0 We have confirmed that all of these results satisfied the specifications. Now EXCEED is ready for launch.
0 Feb 0 @ Tohoku University Symposium on Planetary Science 0 Development of the Extreme Ultraviolet Spectrometer: EXCEED Go Murakami, K. Yoshioka, A. Yamazaki, T. Kimura (ISAS/JAXA) I. Yoshikawa, K. Uji (Univ. Tokyo) F. Tsuchiya, M. Kagitani (Tohoku Univ.) K. Uemizu (NAOJ) Overview of the EXCEED mission (EXtreme ultraviolet spectroscope for ExosphEric Dynamics) An earth-orbiting Extreme Ultraviolet (EUV) spectroscopic mission The first mission of the ISAS/JAXA small scientific satellite series (Sprint-A) EXCEED measures EUV emissions from tenuous gases and plasmas around the planets Observation targets : Mercury, Venus, Mars, Jupiter, and Saturn Major specifications - Launching : August 0 - Weight:0kg -Size:m m 4m -Orbit:90km 0km (LEO) - Inclination: deg ± a few deg. - Mission life :> year - Pointing accuracy : ± arc-min (improved to ±arc-sec by FOV camera) Buffle EUV spectrometer FOV camera (Yoshikawa et al. AdGeo 00,0) Project scientist : I. Yoshikawa (The Univ. of Tokyo) SPRINT-A/EXCEED Instrument overview Specifications Wavelength range 60 4 nm Spatial resolution 0 arc-sec Field of view 400 arc-sec. (FWHM) 0.4.0 nm (depends on slit) Primary mirror 0 cm diameter, f = 60 cm (F/8) Optical layout EUV spectrometer. Selectable by stepping motor, types of shape, types of filter + blank. Laminar type, toroidal, CVD-SiC coated, D = 0 mm, f ~ 400 mm. EUV detector -stage microchannel plate (MCP) + resistive anode encoder (RAE), CsI coated Actuator MCPs Vacuum chamber Slit Move: = 9 positions Blank In CaF 0 60 40 +0 (Dambbel) Opening window Vacuum pipe MCPs should be kept under vacuum -> The window must be opened after launch 4 Sensitivity - (reflectivity) - (diffraction efficiency) -Filter (transmittance) (quantum efficiency) - (spectral and spatial resolution) EUV spectrometer (spectral and spatial resolution) and slit (spatial resolution) Sensitivity (quantum efficiency) 6
Quantum efficiency of the detector -Set the flight detector (MCP with CsI photocathode) and a calibrated detector (MCP without photocathode) on a rotation gimbal -Compare the quantum efficiencies at various wavelengths -Light source: hollow cathode lamp + monochromator (Gas: He, Ne, Ar, and O) -Open and close the window under vacuum Vacuum chamber Flight MCP Calibrated lab-mcp Incident light Rotate Monochromator Hollow cathode lamp 7 Quantum detection efficiency [%] Quantum efficiency of the detector Spectral range: 60-4 nm 00 0 0 0. 0. Requirement FM MCP Lab MCP Flight MCP Lab MCP 60 80 00 0 40 Flight MCP achieved ~00 times higher efficiency than Lab-MCP Quantum efficiency: 0~0% Counts per photon 0-0 - 0-0 -4 Total sensitivity Spectral range: 60-4 nm Blank slit Requirement W/O CsI 60 80 00 0 40 Total sensitivity: ~% (-> Effective area: ~ cm ) 8 EUV spectrometer (spectral and spatial resolution) -EUV spectrometer and the flight mirror are set on a dummy structure -Incident light: F/8 -Light source: hollow cathode lamp We have obtained spectrums of various gases and measured the spectral and spatial resolution Vacuum chamber Flight mirror Hollow cathode lamp Collimator mirror EUV spectrometer Dummy structure 9 0 Source: Ar Source: Ne Slit: 0 Slit: 0
Source: O Source: He Slit: 0 Slit: 0 4 We measured the FWHM of each line 000 Argon Neon Oxygen Helium 000 ArII 46Å Spectra from pinhole slit (after VT) 0.0.0 OI 6Å OI 04Å(M) OII 4Å(M) OII Å(M) ArI 067Å ArI 048Å OI 06Å(M) OI 989Å(M) OI 949Å ArII 9Å ArII 90Å OII 84Å NeI 744Å NeI 76Å NeI 60Å HeI 84Å Spatial resolution -We used a pinhole instead of a slit (included in the flight slit plate) -The FWHM for the spatial axis was measured at each wavelength FWHM (FWHM) [nm] 0. 0 0" slit 60" slit 60 80 00 0 40 0 00 400 600 800 000 X-axis [0bits] 40 0 00 80 60 Wavelength vs. Pixel 0 slit: FWHM < 0.4 nm 60 slit: FWHM <.0 nm Linear!! 0 00 400 600 800 000 Pixel (0~0) Spatial resolution for point source [arc-sec.] 0 0 60 80 00 0 40 Test pinhole (size: 40 um = ) Spatial resolution of 0 is achieved!! 6 Optical test of the whole instrument EXCEED (after final integ.) Collimator and slit (spatial resolution) Collimated light FOV camera 7 -Input collimated light (visible) to whole EXCEED D = 0 cm -Take a slit image by FOV -Measure the FWHM of the pinhole image on the slit -Before/after vibration test Pinhole Collimating mirror 8 0 cm
Optical test of the whole instrument Pinholes Spatial resolution at the slit: FWHM = 4.9 FWHM: 4.9 Slit image by FOV camera Spatial resolution of whole instrument: FWHM < 0 is achieved!! 9 Summary EXCEED will be soon launched in August 0! We have finished the final integration and ground calibrations of EXCEED Quantum efficiency of the detector: >0% -> Total sensitivity: ~% (effective area ~ cm ) : 0. nm (0 slit).0 nm (60 slit) Spatial resolution: 6~0 0 よくわかるEXCEED 測 Thank you!