Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ ÐÎÑÑÈÉÑÊÈÉ�ÍÀÓ×ÍÛÉ�ÖÅÍÒÐ RUSSIAN�RESEARCH�CENTER “KURCHATOV�INSTITUTE” Radiation loss studies on T-10 tokamak using AXUV-detectors Christian Schlatter Presentation of the diploma work 2003, 28 th of March ✫ ✪ 28 th of March 1
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Aim and interest of the present diploma work ————————————————————————– ⋆ AXUV-detectors were installed on T-10 as fast bolometer for the measurement of the total radiated power ⋆ Precise calibration of the detectors was not performed since the start of the operation of the detectors ⋆ Main task of this diploma work: Calibration and characterization of the detectors ⋆ Investigation of different regimes of confinement ✫ ✪ 28 th of March 2
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Structure of the presentation ————————————————————————– ⋆ AXUV-detectors for radiation measurements ⋆ AXUV-setup and calibration on T-10 ⋆ Radiation loss measurements – Calculation of the total radiated power – Reconstruction of the emissivity profile – Study of fast radiation processes ⋆ Conclusion ✫ ✪ 28 th of March 3
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Absolute eXtreme UltraViolet ————————————————————————– ⋆ Si-based ⋆ time resolution of 2 × 10 − 10 s ⋆ high photon sensitiv- ity ⋆ miniaturized ⋆ insensitive to low- energy neutrals ( < 500 eV) ✫ ✪ 28 th of March 4
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ AXUV photon sensitivity ————————————————————————– ⋆ flat sensitivity for E ph > 100 eV ⋆ The manufacturer advertises AXUV for applications in the energy range from 7 eV to 6000 eV. ✫ ✪ 28 th of March 5
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ AXUV low-energy sensitivity hole ————————————————————————– ⋆ Two lines of C III ionization stage and the D α -line lie in the sensitivity hole. ⋆ But: The radiation at photon energies located in the region of reduced sensitiv- ity is not dominant. ✫ ✪ 28 th of March 6
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Limited lifetime of AXUV ————————————————————————– ⋆ The stability of sen- sitivity is guaranteed up to a flux of 10 16 photons of 100 eV ⋆ The radiation dose was one order of magnitude below this limit for the totality of discharges in 2002. ✫ ✪ 28 th of March 7
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Detector pyroelectric bolometer setup�on time�resolution T-10 � 10�ms chord resolution 16�channel � 4�cm in�the AXUV-detector center�of�the vessel time�resolution 20 s � � ✫ ✪ 28 th of March 8
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ AXUV-detector calibration ————————————————————————– AXUV- ⋆ The spreading of sensitivity array and amplifiers of the individ- lamp ual channels is compensated slit by weighting factors f i (of or- der of unity), which are mul- pinhole�camera tiplied with the detector sig- 30 amp�voltage�[mV] nals. 20 ⋆ f i were determined in the 10 laboratory using a simple 0 lamp as radiation source. -200 -150 -100 -50 0 50 100 150 200 ✫ ✪ lamp�position�[mm] 28 th of March 9
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Calculation of the radiated power ————————————————————————– ⋆ The geometry of the fields of view of the detectors is precisely calculated tak- ing into account the diagnostics flange. ⋆ The absolute power values p i (power toroidal view�of radiated power per unit of toroidal length) the�flange are calculated using an average sensitivity top�view of < η > = 0.24 A/W 710 of�the 55 14 flange ⋆ Simple calculation of the total radiated -400 -200 0 200 400 power by P = 2 π · R · � 16 i =1 p i ✫ ✪ 28 th of March 10
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ AXUV as fast bolometer ————————————————————————– ⋆ The power loss is dom- inated by tungsten line radiation (flat η region) from the center. ⋆ AXUV and the pyro- electric detector show good agreement for this discharge. #32441, I p = 250 kA, B T = 25 kG, < n e > = 2.6 × 10 13 cm − 3 (@ t=700 ms). ✫ ✪ 28 th of March 11
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Checking of the sensitivity hole ————————————————————————– ⋆ The neon-puffing started in t = 700 ms (#34596). ⋆ AXUV sees the most intense neon lines (around 30 eV) with a reduced sensitivity of η neon = 0.18 A/W. ⋆ The calculation of the addi- tional radiation due to neon (with η neon ) agrees with the Discharge #34593 without and pyroelectric detector. #34596 with neon gas puffing. ✫ ✪ 28 th of March 12
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Thin carbon film ————————————————————————– ⋆ After operation on T-10, a thin film of probably carbon was deposited on the detectors. ⋆ The color of the film suggests a thickness of at least 70 nm. ⋆ The example of neon puffing showed no decrease in sensitivity at E ph ≈ 30 eV. ⋆ The checking with an He-Ne laser (E ph = 2 eV) did not show a drop in sensitivity at the lower end of photon energy. ✫ ✪ 28 th of March 13
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Reconstruction of � 1 a i1 � 2 the emissivity a i2 � 3 a 31 � j a 21 a ij a 32 ⋆ The cylindrical symmetry of the discharge is assumed → ε ( r ) � m a 22 a 11 a ii ⋆ The pixels A = { a ij } are defined by the intersection of the rings with constant emissivity ε j with the i th detector chord of bright- ness g i = � 8 j =1 a ij · ε j ⋆ Reconstruction by ε j = A − 1 g i method described in: Кузнецов, Щеглов; Методы диагностики высоко-температурной плазмы; g i g 3 g 2 g 1 g m ✫ ✪ Москва, 1974 г. 28 th of March 14
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ An example ————————————————————————– Discharge #31899 (T-10 H-mode regime) ✫ ✪ 28 th of March 15
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Deuterium pellet: total power ————————————————————————– ✫ ✪ 28 th of March 16
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Power lost by low-energy neutrals ————————————————————————– ⋆ The power lost by low-energy neutrals can be obtained by the difference between the pyro- electric bolometer and the sum of the AXUV-chords. as suggested in: Boivin et al., High resolution bolometry on the Alcator C- Mod tokamak (invited) ; Rev. Sci. Inst., 70, (1999). ✫ ✪ 28 th of March 17
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Deuterium pellet: individual chords ————————————————————————– ✫ ✪ 28 th of March 18
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Deuterium pellet: emissivity & Z eff ————————————————————————– ( r = 0) = ε ( r =0) ·� Z � 2 AXUV: Z AXUV eff n 2 e · R ( T e ,Z ) Spitzer: < σ Spitzer > = 8 . 7 × 10 13 � r ( q =1) − r ( q =1) dr T 3 / 2 1 e ln Λ � � �� 0 . 46 Z eff 0 . 29+ ✫ ✪ Zeff +1 . 08 28 th of March 19
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Fast processes : Pellet-Injection ————————————————————————– Discharge #35886 ⋆ D-Pellet t 3 injection t 1 speed t 2 1 km/s. ⋆ Snakelike 1 x 10 557.2 radiation channel power [W/cm] 3 557 pattern. 2 556.8 ⋆ t 1 = 556.4, 1 556.6 t 2 = 556.6 0 556.4 and t 3 = −30 −20 556.2 −10 0 time t [ms] 556.8 ms. 10 ✫ 556 ✪ 20 minor radius r [cm] 30 28 th of March 20
Christian Schlatter ✬ Radiation loss measurements with AXUV ✩ Fast processes : Pellet-Injection ————————————————————————– ⋆ The q=1 surface is lo- geometry�of�the�snake cated at the position of the radiation peak ⋆ The geometry of the snake is a tilted and displaced circle, turning toroidally. ⋆ The corresponding rota- tion speed is 23 km/s. Wesson, J.A.; Snakes , Plasma Physics and Controlled Fusion, vol. 37, (1995). ✫ ✪ 28 th of March 21
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