X-ray Spectroscopy on s An ongoing discussion between the two Manfreds Manfred von Hellermann for CXRS Manfred Bitter for x-ray spectroscopy G. Bertschinger for many contributers (Bitter, Kunze, Weinheimer, Marchuk, Urnov,..) Forschungszentrum Jülich, Institut für Energieforschung IV (Plasmaphysik), Assoziation FZJ-EURATOM,Partner in the Trilateral Euregio Cluster, FRG 1
Introduction Physical quantities measured by x-ray spectroscopy Some spectroscopic basics, line broadening and line shift, line intensities, elements, ionization stages, spectra 1-D results Instruments Imaging Bragg spectrometers 2-D measurements Outlook to ITER 2
Impurity sources in fusion plasmas Plasma facing components low z (Be, B, C, O) medium z (Si, Ti, Fe-group, Cu) high z (Mo, Wo) Impurities applied to Plasma (enhanced radiation losses, radiative mantle concept, transport studies) low z (Ne) medium z (Ar, Kr, Ti, Cr, Fe...) 3
Spectroscopic Basics : Line Broadening and Shift Doppler effect 0 (1 Thermal (Maxwellian Plasma) P( ) d FWHM mc 2kT Natural line broadening for resonance lines (Lorentz) No Stark and collisional broadening 2 2 exp v c mc 2 0 2 8kT ln2 0 2 m0c ) ( 0 kt 0 2 ) 2 d T FWHM 0.00244* 0 T[ kev] 4
Basics : Abundance of Ionization stages X-ray spectroscopy (0.05... 0.7 nm) medium and high z impurities Medium z elements: He and H-like high z elements Ne-like, at very high temperatures He-like. 5
Basics : Excitation of ions (He-like Cr) P.Platz
7 Sensitivity of the electron temperature dependencies e sw e e w w s T E T T Y I I exp ) ( 1 ~ * e S n s n s T E I I exp ~ 2) ( 3) ( Satellite to resonance (w) Triplet to singlet Satellite to satellite ) ( ) ( ~ exp ) ( ) ( ~ * * * * e w e l e lw e w e l w l T Y T Y T E T Y T Y I I
Temperature dependence of n=2 satellite to resonance line intensity 8
Sensitivity of plasma parameters to measured quantities T e ~ (I k / I w ) (0.4..0.5) v rot ~ line shift Li- / He-like ~ (I q,r / I w ) T i ~ 2 D H- / He-like contribution to triplet-line appr. 10% n 0, H- / He requires detailed spectral modeling estimated accuracy 50% 9
Modelling of He-like spectra (argon) Fitting of the spectrum with physically relevant parameters : T i, T e, v rot, He-like, Li/He-like, H/Helike deviation at y~15% 10
Theoretical model and fit to experiment Model spectrum about 1000 components T i, v rot, T e, Li- / He-like H- / He-like background 11
Ion temperature and plasma rotation (M. Bitter et al. EPS 2000) 12
Electron temperature measurement spectroscopic / ECE 13
Electron temperature obtained from ratio singlet to triplet (n=3) Measurements and new calculations confirm measurements on PLT and resolve contradictions to the HULLAC code 14
Li-like Ar 15+ for ohmic and Neutral beam heated plasmas relative to coronal expectations 15
Density of Li-like Ar 15+ for ohmic plasmas with cascades Cascades reduce Lilike abundance by about 20% asymptotic behaviour is compatible to coronal expectations rates for calculations of coronal are correct 16
Estimate of H-like argon Li-like abundance and recombination of H-like provide diffusion coefficient and density of neutral hydrogen hydrogen density between 1*10 8 and 2*10 7 cm -3 support by transport codes radial profiles recommended 17
Comparison of new calculations with previous gas puff experiments (XUV and x-ray spectroscopy) X-ray He-like/RITM XUV 18
Principle of an imaging Bragg spectrometer Eggs, Ulmer 1965 Bitter, Fraenkel 1998 19
Shape of focal lines Bragg condition is fulfilled on a cone around the crystal normal Focal lines curved Focal curves on detector : conical intersections Aperture to the plasma curved too 20
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250 53.4 mm 200 intensity / a. u. 150 100 50 0 3.93 3.94 3.95 3.96 3.97 3.98 3.99 4 4.01 wavelength / Angstrom 400 middle 350 300 intensity / a. u. 250 200 150 100 50 0 3.93 3.94 3.95 3.96 3.97 3.98 3.99 4 4.01 wavelength / Angstrom 300-53.4 mm 250 intensity / a. u. 200 150 100 50 0 3.93 3.94 3.95 3.96 3.97 3.98 3.99 4 4.01 wavelength / Angstrom 6000 W He-like, singlet Q,R Li-like Z He-like, triplet 2000 6000 5000 4000 3000 2000 intensity (arb. units) 1000 0-150 -100-50 0 50 100 150 y (mm) 1500 1000 intensity 500 (arb. units) 0-150 -100-50 0 50 100 150 y (mm) 5000 4000 3000 2000 intensity (arb. units) 1000 0-150 -100-50 0 50 100 150 y (mm)
Ion and electron temperature, toroidal plasma rotation Properties of the spectrometer as expected Provides local plasma parameters Room for developments (ITER, W7-X) 23
M.Bitter et. al. APS 2007 24
M.Bitter et. al. APS 2007 25
M.Bitter et. al. APS 2007 26
X-ray spectrometers for ITER (EU design) 6 imaging spectrometers 3 perpendicular (poloidal rotation) 3 angle 30 deg (toroidal rotation) For the edge spectrometers problems with the detectors, arrays of non-imaging spectrometers will do the job 27
Crystals and Bragg angles for the ITER x-ray spectrometer 28
Crystal support Narrow range of Bragg angles 50.05 +-.4 deg All elements share the same aperture Very simple change mechanism for different crystals Rotational stage only In situ calibration by x- ray lines 29
Expected signal for He-like Kr, fraction 10 ppm, includes background and count statistics 30
Conclusions X-ray spectroscopy measures T i, v rot, T e, concentration and ionisation stage of medium-z impurities and estimate density of neutral hydrogen Simple spectra, well understood, no background lines Toroidal and poloidal rotation Highest accuracy in the center, lower at edge Novel detectors with very high dynamic range Will be installed on ITER by US Simple and robust Complementary to CXRS 31