the feasibility study of the euv spectroscopic...
TRANSCRIPT
The Performance of the EUV Spectroscope (EXCEED) Onboard the SPRINT-A Mission
K. Yoshioka, G. Murakami, A. Yamazaki, K. Uemizu , T. Kimura (ISAS/JAXA),
I. Yoshikawa, K. Uji (Univ. Tokyo)
F. Tsuchiya, and M. Kagitani (Tohoku Univ.)
EXCEED
• The observing module contains – Entrance mirror
– Spectrometer
– Slit with filters
– Grating
– EUV detector
– Light trap
– Target finding camera
• Total weight : 99kg
(↑) The inner part of the EUV spectrometer () The schematics of the EXCEED instrument (without bus system)
2
EXCEED current status • The assembly of the spectrometer part is completed
in last January.
• The main body has been constructed.
• Environmental tests have been done.
• EXCEED is integrated on the bus module ! SPRINT-A
• SPRINT-A is under final environmental test at ISAS
EUV-E FOV-E
MDP
EUV
Baffle
Dec. 2012
Jan. 2013
Feb. 2013
Feb. 2013 (@ISAS)
3
EXCEED optical layout
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
4
EXCEED/Entrance mirror
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
5
EXCEED/Entrance mirror
• The reflectivity of the entrance mirror has been evaluated successfully. • The shape (optical performance) has been evaluated.
The reflectance of FM mirror
60 80 100 120 1400
0.2
0.4
0.6
Wavelength [nm]
Refl
ecti
vit
y
Measured (FM) Theoretical
6
Photo of the entrance mirror with alignment mirror (FM)
EXCEED/Slit with filters
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
7
60 80 100 120 14010-2
10-1
100
Wavelength [nm]
Tra
nsm
itta
nce
Indium CaF2
• Three types of slit shape. – 10”
– 60”
– dumbbell
• Two types of filters and blank (without filter). – Blank (w.o. filter),
– Indium t=100nm,
– CaF2 t=3mm
• 3×3 = 9 types of slits.
Transmittance of FM filters
Photo of Slits plate (reflective surface) 8
EXCEED/Slit with filters
Io torus observation by dumbbell slit.
EXCEED/FOV guiding camera
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
9
EXCEED/FOV guiding camera
Slit images taken by FOV camera. The focus is OK.
10
EXCEED/Grating
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
11
EXCEED/Grating
• The diffraction efficiency of FM Grating has been evaluated successfully. • The difference between theoretical and measured values are possibly due to the
surface roughness. But not critical.
The reflectance of FM grating
60 80 100 120 1400
0.1
0.2
0.3
Wavelength [nm]
Dif
fracti
on e
ffic
ien
cy
Measured (FM) Theoretical
12
EXCEED/Light trap
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
13
EXCEED/Light trap
0th order
Lyman-α(-1st )
• Light trap is set in order to capture the 0th order light and -1st order Lyman alpha (121.6nm) which may cause serious stray light problem. 14
The photo of the light trap (FM) The photo of the spectrometer (FM)
EXCEED/MCP+RAE
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
15
60 80 100 120 1400.1
0.5
1
5
10
50
100
FM MCP Lab MCP
Quan
tum
det
ecti
on e
ffic
iency
[%
]
Wavelength [nm]
• CsI photocathode is deposited on the MCP surface • The detection efficiency increase x1.5~x100 • The MCP should be kept under vacuum until the launch.
EXCEED/MCP+RAE
16
The absolute efficiency of the detector (FM) (see the next presentation)
EXCEED/MDP
• Entrance mirror • An off-axis parabolic,
CVD-SiC coated
• Slit • Three types of shape,
and three types of filters
• Grating
• Laminar type, toroidal, CVD-SiC coated
• Photon detector
• Microchannel plate and Resistive anode
The optical layout of EXCEED
Baffle
Entrance mirror
Slit-1
Target
FOV Grating
MCP+RAE
MDP
Slit-2 Slit-9
Light trap
17
Total sensitivity (with/without filters)
The sensitivity of EXCEED. (The integration time is assumed as 50 minutes. The field of view is assumed 10”×10”)
60 80 100 120 14010-4
10-3
10-2
10-1
Wavelength [nm]
Co
unts
per
ph
oto
n
Direct Indium CaF2
60 80 100 120 14010-2
10-1
100
101
Wavelength [nm]C
oun
ts p
er
Ray
leig
h (
10"x
10",
50
min
.) Direct Indium CaF2
The total sensitivity (Photon to count conversion factor) as a function of wavelength. The version with Indium filter (red) and CaF2 filter (blue)
18
Optical performances ~Entrance mirror slit~
• The FWHM of the spot diagrams are smaller than 10 arc-seconds.
Tsukuba, 2013/01/20 19
Optical performances ~Slit MCP~
0 200 400 600 800 1000
1000
2000 Argon Neon Oxygen HeliumO
I 1304Å
(M)
ArI
1067Å
ArI
1048Å
ArI
I 932Å
ArI
I 930Å
OII
834Å
NeI
744Å
NeI
736Å
HeI
584Å
X-axis [10bits]
OI
1026Å
(M)
OI
989Å
(M)
NeI
630Å
OI
1356Å
OII
1154Å
(M)
OII
1132Å
(M)
ArI
I 1463Å
OI
949Å
Spectra from pinhole slit (after VT) 2012.01.10
20
Optical performances (spatial and spectral resolutions)
60 80 100 120 1400
5
10
15
Wavelength [nm]
Spati
al
reso
luti
on f
or
poin
t so
urc
e[a
rc-s
ec.]
60 80 100 120 1400
0.5
1
Wavelength [nm]
Spec
tral
res
olu
tion
(F
WH
M)
[nm
]
Point source 10" slit 60" slitSpatial resolution (FWHM) as a function of wavelength.
Spectral resolution (FWHM) as a function of wavelength for various slits.
Spatial resolution: 6~10 arc-seconds Spectral resolution: 0.3nm ~ 1nm.
21
O+ 83nm resonant scattering (escaping plasma)
charge exchange (solar wind)
H 121nm resonant scattering O 130nm resonant scattering (exospheric neutral particle)
O+ 83nm resonant scattering (ionosphere)
(2) Spectral analysis for aurora and gas torus.
Jupiter and Saturn
(1) Simultaneous observation of exosphere, ionosphere, and escaping plasma down the tail.
Venus, Mars, and Mercury
FUV/EUV aurora H2 Lyman & Werner bands
Allowed transition lines of S,O ions (satellite origin)
Io plasma torus : Cassini/UVIS. Jupiter’s UV aurora : HST/WFPC2
Two primary science targets
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Escaping atmosphere from terrestrial planets
O+ 83nm resonant scattering (escaping plasma)
charge exchange (solar wind)
H 121nm resonant scattering O 130nm resonant scattering (exospheric neutral particle)
slit
EXCEED will measure outflow rate of the atmosphere (O+. C+, N+) depending on solar (wind) conditions (short-term) from Mars and Venus
O+ 83nm resonant scattering (ionosphere)
Through the simultaneous observation of exosphere, ionosphere, and escaping plasma down the tail, EXCEED will reveal * The total amounts of escaping atmosphere * Its dependency on Solar wind activity The targets are Venus, Mars, and Mercury.
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Can EXCEED detects the faint targets?
0 10 20 3010-2
10-1
100
101
102
Accumulation time [Days]
Bri
ghtn
ess
[R
] (A
vera
ged f
or
FO
V)
Worst caseSeff = 1cm2
Nominal caseSeff = 3cm2
FOV = 10"x10"Spectral resolution = 0.3nm (FWHM)Lower limits to be SNR=1
24
Can EXCEED detects the faint targets?
0 10 20 3010-2
10-1
100
101
102
Accumulation time [Days]
Bri
gh
tness
[R
] (A
vera
ged
fo
r F
OV
)
Worst caseSeff = 1cm2
Nominal caseSeff = 3cm2
FOV = 10"x60"Spectral resolution = 0.9nm (FWHM)Lower limits to be SNR=1
25
The energy flow around the Io plasma tours
• There must be an extra energy source.
• A small amount of hot electron is the candidate.
• The hot electron component has been detected through in situ observation by Galileo space craft.
Hot electrons
The extra energy source
Frank and Paterson, 1999 mod.
Ions : S+, S++, S3+, S4+, O+, O++, Na+, Cl+
electrons:
(~5 eV, ~2000 ele./cc)
Pick up energy
EUV radiation ~ 2 TW
Fast neutral
Transport
Can we detect hot electrons through remote observation? 26
The approach for Io plasma torus ~spectral diagnosis~
EUV-FUV spectrum taken by Cassini/UVIS (Steffl et al. 2004b)
• EXCEED will take spatially resolved spectra
• Emission line intensities from the Io torus depend on the ambient electron temperature.
• The EUV spectra tell us not only the ion composition but also the electron temperature.
1 10 100 1000
10-9
10-8
10-7
10-6
Electron temperature [eV]
Em
issiv
ity [
eV
cm
3/s]
S++ Emissivity through the electron impact excitation. The calculation use the CHIANTI database.
Visible (631nm)
EUV (120nm)
EUV (68nm)
27
EUV is the best band for spectral diagnosis
More than 80% of the lines are in the EUV region.
The distribution of Sulfur ion emissions. These emissivities are calculated with same plasma conditions (Yoshioka et al. 2012).
Ground based obs. Space based obs.
28
EUV observation of Io tours from EXCEED
60 80 100 120 1400
100
200
Wavelength [nm]
Counts
/pix
FOV = 10" x 10"Integration time = 50 minutes
60 80 100 120 1400
100
200
Wavelength [nm]
Counts
/pix
FOV = 10" x 10"Integration time = 50 minutes
• EXCEED can distinguish the spectra with and without hot component by the 1 orbit (50min.) observation..
Model spectra with hot electron 4.2% Model spectra with hot electron 0%
29
Summary and next steps
• Flight model of the whole EXCEED instruments have been evaluated. (good!) – Entrance mirror, slit, filter, detector
• The EXCEED structure has been installed and the optical performances have been evaluated. (good!)
• EXCEED will be launched in next August from Uchinoura Space center.
30