Status of Equatorial CXRS System Development

1. Status of Equatorial CXRS System Development S. Tugarinov, Yu. Kaschuck, A. Krasilnikov, V. Serov SRC RF TRINITI, Troitsk, Moscow reg, Russia. E-mail: tugar@triniti.ru

2. 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.

3. 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.

4. Five mirrors optical system integration into E-port #3 r/a=1 Version September 2005 r/a=0.5

5. 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.

6. Five mirrors optical system focusing properties m r/a=1 • Five view chords distributed from r = a to r = a/2 • Color of spot correspond to Hα, He II and CVI wavelength r/a=0.5 m m m m Focal plane

7. 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.

8. Version December 2005 r/a=1 r/a=0.5 r/a=0.3

9. Only flat and spherical mirrors was used for design to make optical system more simple in alignment and practically feasible.

10. Four mirrors optical system focusing properties m r/a=1 r/a=0.5 r/a=0.3 m m Focal plane

11. 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.

12. Experimental scheme for numerical simulation 3 4 2 5 1 6 r/a=1 7 8 r/a=0.3

13. 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.

14. DNB’s parameters for numerical simulation • “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.

15. 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)

16. DNB’s profiles • “Negative” DNB “Positive” DNB

17. DNB’s attenuation in plasma column • “Negative” DNB “Positive” DNB

18. Radial distribution of active CX He II line (white) and background (red) intensity along view chord integrated • “Negative” DNB “Positive” DNB

19. Radial distribution of active CX CVI line (white) and background (red) intensity along view chord integrated • “Negative” DNB “Positive” DNB

20. With DNB modulation the signal-to-noise ratio (SNR) is calculated for the case of continuum radiation fluctuations as the mainnoise source. - Thus, the SNR value calculated as: • I’cx – signal from CX lines [ 1/s ] • I’cx – signal from continuum radiation [ 1/s ] •  - integration time [ s ]

21. 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

22. 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

23. 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.

24. 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.

25. 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

26. New design of HRS • 1. Entrance slit. 3. Spherical mirror. 5. Correction element • 6. Echelle grating. 7. Detector box.

27. New design of HRS • 1. Entrance slit. 5. Correction element. • 3. Spherical mirror. 6. Echelle grating (400 mm length). • 4. Flat mirror with hole.

28. 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.