Status of Equatorial CXRS System Development
S. Tugarinov, Yu. Kaschuck, A. Krasilnikov, V. Serov
SRC RF TRINITI, Troitsk, Moscow reg, Russia.
E-mail: [email protected]
Main directions of the CXRS diagnostic development in RF
• 1. Collection optical system design and integration into the equatorial port plug # 3.
• 2. Numerical simulation.
• 3. Data analysis development.
• 4. Measurement methodology development.
• 5. Specific spectroscopic instruments development.
General scheme of CXRS for ITER
-Distribution of the
CXRS periscopes
looking at the DNB.
-Russia responsible
for two periscopes
at the E-port # 3 for
plasma edge
measurements.
Five mirrors optical system integration into E-port #3
r/a=0.5
r/a=1 Version September 2005
1. Collection optical system design and integration in to port plug
• Optical system design and imaging properties optimization was carried out by ZEMAX software.
• Imaging scale is 10 : 1. • Collection optical system has agree with
spectral instrument light throughput.• Individual spectrometer will be used for
each view chord.
Five mirrors optical system focusing properties• Five view chords distributed from r = a to r = a/2• Color of spot correspond to Hα, He II and CVI wavelength
r/a=1
r/a=0.5
Focal plane
At the RF - EU Workshop devoted to ITER CXRS diagnostic development that took place in TRINITI (14–16 September, 2005) was suggested:
• Extend equatorial port observation system up to r = 0.3a for deep overlap of edge and core measurement systems and extend the plasma region where poloidal and toroidal plasma rotation could be separate.
• Achieve the best possible spatial resolution at the plasma periphery for edge physics studies.
Version December 2005
r/a=1
r/a=0.3
r/a=0.5
• Only flat and spherical mirrors was used for design to make optical system more simple in alignment and practically feasible.
Four mirrors optical system focusing properties
r/a=0.3
r/a=1
Focal plane
r/a=0.5
2. Numerical simulation
• Involve all physical processes analysis that be the result of CXR reaction inside beam volume.
• Allow estimate measured signals value and SNR value.
• In general, allow estimate abilities and efficiency of CXRS diagnostic for ITER application.
Experimental scheme for numerical simulation
r/a=1
r/a=0.3
1
2345
6
7
8
Plasma parameters for numerical simulation
• Electron density 1 1020 m-3 with a flat profile.• Center temperature ~20 keV with parabolic shape.• Equal electron and ion temperature.• Uniform impurity composition along radius :
D and T = 77%, C = 1.2%, Be = 2%, He = 4% with respect to ne ( that correspond Zeff = 1.7 ).
• Integration time = 0.1 sec .
• The simulation was carried out for He II 468.6 nm; BeIV 465.8 nm and C VI 529.1 nm lines.
DNB’s parameters for numerical simulation"Negative Ion" Beam
( 100 keV/amu)
"Positive Ion" Beam (80 keV/amu)
Voltage (kV) 100 H0 160 D0
Current densityin focal position (mA/cm2)
70 183, 23, 29
E, E/2, E/3
Beam 1/e – radius (m)
0.1 0.042, 0.056, 0.07
stop (10-20 m2) 2.28 2.63, 4.16, 5.32
• “Negative Ion” beam – this is a beam which created with negative ion source use.
• “Positive Ion” beam – this is a beam which created with positive ion source use.
We have create original software for CXRS numerical modeling, instead of DINA code simulation.
Atomic data for cross section <σ> and rate coefficients <σv> was simulated using ADAS code.
(We are very appreciate to Dr. M. von Hellermann for help with atomic data)
DNB’s profiles
• “Negative” DNB “Positive” DNB
DNB’s attenuation in plasma column
• “Negative” DNB “Positive” DNB
Radial distribution of active CX He II line (white) and background (red) intensity along view chord
integrated
• “Negative” DNB “Positive” DNB
Radial distribution of active CX CVI line (white) and background (red) intensity along view chord
integrated
• “Negative” DNB “Positive” DNB
- With DNB modulation the signal-to-noise ratio
(SNR) is calculated for the case of continuum
radiation fluctuations as the main noise source.
- Thus, the SNR value calculated as:
cxff
cx
II
ISNR
2
• I’cx – signal from CX lines [ 1/s ]
• I’cx – signal from continuum radiation [ 1/s ]
- integration time [ s ]
Signal-noise ratio value radial distribution for uniform 2.5 A0 (red) and variable 2.5 - 0.5 A0 (white)
spectral resolution for He II line• “Negative” DNB “Positive” DNB
Signal-noise ratio value for uniform 2.5 A0 (red) and variable 2.5 - 0.5 A0 (white) spectral
resolution for CVI line
• “Negative” DNB “Positive” DNB
• Comparison of "negative" and "positive" DNB show advantageous of "positive" DNB application for edge CXRS and acceptability for core CXRS measurements.
• "Negative" DNB with 100 keV/amu energy have less attenuation coefficient and penetrate further into the plasma core, therefore gives advantageous for core measurements.
5. Specific spectroscopic instruments development
• For the CXRS diagnostic, high resolution, high light throughput spectrometer (HRS) based on echelle grating was design.
• Spectral range: 200 – 900 nm.
• F-number = 3.
• Stigmatic image.
• Max. spectral resolution: 0.1 A0.
• Average linear dispersion: 2.5 - 3 A0/mm.
• Dispersion range: 2 – 20 A0/mm.
Optical scheme of new HRS design
• 1 – Entrance slit• 2 – Flat mirror• 3 – Spherical mirror• 4 – Flat mirror with
hole• 5 – Correction
element• 6 – Echelle grating• 7 – Image plane
New design of HRS
• 1. Entrance slit. 3. Spherical mirror. 5. Correction element• 6. Echelle grating. 7. Detector box.
New design of HRS
• 1. Entrance slit. 5. Correction element.• 3. Spherical mirror. 6. Echelle grating (400 mm length).• 4. Flat mirror with hole.
Conclusion
• We plan continue activity in all directions of the CXRS diagnostic development :
• 1. Collection optical system design and integration into the port plug # 3.
• 2. Numerical simulation.
• 3. Data analysis development.
• 4. Measurement methodology development.
• 5. Specific spectroscopic instruments development.