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Spectrometric Diagnosis Group in Plasma Chemistry and Physics

Spectrometric Diagnosis Group in Plasma Chemistry and Physics. 박영동 1 , 오수기 2 1 Department of Chemistry, 2 Department of Physics, Ajou University, Suwon 443-749, Korea. Vision/Mission. High Resolution Spectroscopy/Optical Diagnosis Group Chemistry Laser Spectroscopy

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Spectrometric Diagnosis Group in Plasma Chemistry and Physics

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  1. Spectrometric Diagnosis Groupin Plasma Chemistry and Physics 박영동1, 오수기2 1Department of Chemistry, 2Department of Physics, Ajou University, Suwon 443-749, Korea

  2. Vision/Mission High Resolution Spectroscopy/Optical Diagnosis Group Chemistry Laser Spectroscopy Molecular Beam Spectroscopy Photoionization Spectroscopy Physics Interferometry Optics Fabry-Perot Atomic and Plasma Physics

  3. Stength/Capacity Chemistry Molecular Spectroscopy Theoretical Spectroscopy Physics Optics – Fourier optics, interferometry Plasma Physics

  4. TokamakPlasma The magnetic field lines inside the tokamak chamber are divided into two groups: the magnetic separatrixsurface One forming nested closed surfaces in the main chamber without touching the material wall the other leading to the divertor chamber the “scrape-off” region cold and diluted the “core” region hot and dense

  5. The heatingeffect of the electric current, joule-heating, is less than 50 million degrees. The need for additional heating has led to neutral beam heating. CXS is an appropriate tool to measure the effect of neutral beam heating.

  6. The Charge Exchange Recombination Spectroscopy (CXRS) Doppler broadening ion temperature Doppler shift poloidal and toroidal rotation speed impurity density total intensity • H0 + C6+→H+ + [C5+]* charge exchange between neutrals in the neutral beams and ions in the plasma

  7. CXRS system in JT-60U

  8. Doppler Broadened Data

  9. Fabry-Perot interferometer Mirrors Photon counter Piezo actuator

  10. Design of a spectrograph system for temperature measurement in Fusion Reactor using Doppler Broadening Fabry-Perot interferometer system Advantages can achieve very high spectroscopic resolution Disadvantages 1. Need very sharp filter to separate photones outside of free spectral range 2. input beam should be stable during scan period. 3. hard to employ large aperture system

  11. McPn CXRS McPherson Model 2062 2-meter focal length f/14.1 Monochromator, $200,000 2-meter

  12. AJOU CXRS 50 cm CCD Focusing Mirror Grating 2 1800 gr/mm 1st order Grating 1 1200 gr/mm -1st order Light Source Collimating Mirror Entrance Slit

  13. AJOU CXRS

  14. AJOU CXRS

  15. AJOU CXRS Ne I =529.8189 nm Ne I =530.4758 nm Ne I =528.0085 nm FIG. 4. The measured Ne I spectrum lines by the two-grating spectrometer equipped with the PhotonMax 512B CCD camera.

  16. AJOU CXRS McPherson spectrometer(80 ms) Ajoutwo-grating spectrometer(46 ms) McPn CXRS The Ajou system is ~10 times better in S/N for a fraction of the cost for ‘old’ system. FIG. 5. The spectrum signals are obtained with the two-grating spectrometer (triangle) and conventional spectrometer (square) for the KSTAR plasma. It is shown that the S/N ratio of the two-grating spectrometer is much larger than that of the conventional spectrometer.

  17. FIG. 6.(a) The ion temperature profiles and (b) toroidal rotation velocity measured with both spectrometers for the KSTAR plasma shot number of 4364are compared.

  18. ITER CXRS optical fiber bundle the viewing lines diagnostic neutral beam spectrometers The Charge Exchange Recombination Spectroscopy (CXRS) system in an upper port plug for ITER. Figure from http://www.rijnhuizen.nl/annual_report/2007/02_the_research_at_rijnhuizen/2_2.html

  19. What’s Next? JT-60U K-STAR Increase S/N by a factor of 3 or greater. Needs a CCD detector at Ajou. Design multilayer spectrometer systems. A few researchers.(Grads, Post doc.)

  20. 올해도 복스러운 해가 되기를 기원합니다

  21. [Spectroscopic principle for CXRS]Neutral atom (H0) and impurity ion (Aq+) undergo a charge transfer that leaves the product ion in an excited state. • H0 + Aq+→ H+ + [A(q-1)+]* • Aq+ = C6+. carbon is one of intrinsic impurities and they are fully stripped throughout the plasma volume. Emissions are excited at wavelengths long enough for making accurate Doppler broadening and shift measurements. [Diagnostic Method]One of heating beams NB #14 is used for this measurement (see figures). Due to the above reaction, carbon ions near the neutral beam emit green light (529.2 nm at n=8-7 transition). • Doppler broadening (→ temperature), Doppler shift (→ rotation velocity) and its area (→ impurity density). According to the ionization balance, there are C5+ ions in the edge region, which can emit at the same transition due to direct excitation by electrons (not by neutral beams). Therefore it is important to separate the spectrum by beam excitation from that by electron excitation. In order for this, CXRS system in JT-60U has an exclusive optics for the background spectrum. From Y. Koide, A. Sakasai, Y. Sakamoto, H. Kubo and T. Sugie, Rev. Sci. Instrum. 72, 119 (2001)

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