Burckhart, A.

Fischer, R.

Hicks, N.

Kurzan, B.

Wolfrum, E.

English

MPG.PuRe

Multiple diagnostic data analysis of density and temperature profiles inASDEX UpgradeR. Fischer, A. Burckhart, N. Hicks, B. Kurzan, E. Wolfrum, ASDEX UpgradeT amMax-Planck-Institut für Plasmaphysik, EURATOM Association, D-85748 Garching, GermanyA major challenge in nuclear fusion research is the coherent combination of measurementsfrom heterogeneous diagnostics. Different measurement techniques for measuring the samesubset of physical parameters provide complementary and redundant data for, e.g., improv-ing the reliability of physical parameters, considering all dependencies within and betweendiagnostics, and resolving data inconsistencies. Coherent combination means the integration ofdiagnostics raw data including forward modeling instead of the combination of diagnostics re-sults which frequently relies on cumbersome iterative procedures. The Integrated Data Analysis(IDA) approach provides a full probabilistic model including physical and statistical descriptionof an integrated set of different diagnostics.IDA was applied to analyse the combined data from Lithium beam (LIB), DCN interferom-etry, electron cyclotron emission (ECE), and Thomson scattering (TS) diagnostics at ASDEXUpgrade to obtain full electron density and temperature profiles with a temporal resolution ofup to 50µs and a spatial resolution up to 5 mm at the plasma edge. Interdependencies of profilesbetween different diagnostics are fully considered. IDA enables us to study the fast temporalevolution of density, temperature and pressure profiles for inter-ELM phases as well as ELMresolved [1].0 0.2 0.4 0.6 0.8 1ρpol0.00.51.0n e (1020 m−3 )0123456Te (keV)#232273.435s0.9 0.95 1 1.05ρpol0.00.20.40.6n e (1020 m−3 )00.20.40.60.81Te (keV)#232273.435sFigure 1: Temperature and density profiles with error bars as afunction of normalized poloidalradius of the combined data from ECE, LIB and DCN interferometry with 1 ms temporal reso-lution (left: full; right: pedestal profiles)36th EPS Conference on Plasma Phys. Sofia, June 29 - July 3, 2009 ECA Vol.33E, P-1.159  (2009)Figure 1 shows temperature and density profiles for an H-mode discharge (#23227) obtainedwith the probabilistic analysis of the combined ECE, LIB and DCN interferometry data (left),and the details around the pedestal region (right). The error bar of the density profile is deter-mined mainly by the LIB data at the pedestal and the 5 chords of the DCN interferometer wherethe line of sights are tangential to the flux surfaces. The error bar of the temperature profileis small at the nominal positions of the ECE channels and large where no ECE measurementsexist and where the plasma is optically thin.0 0.2 0.4 0.6 0.8 1 1.2ρpol−2−10123456Te (keV)dataresiduemodeled data0.9 0.95 1 1.05ρpol−500−400−300−200−1000profile gradientsdTe/drdne/drdpe/drFigure 2: Left: Measured (black dots) and modeled (red line) ECE temperatures, and residuals(green dots). The ECE shine-through region is emphasized with an ellipse. Right: Gradients ofelectron temperature (eV/cm), density (1011/cm4), and pressure (10 Pa/cm).Since the data of the different diagnostics are analyzed jointly, the simultaneous informationabout density and temperature allows to mask out the ECE channels where the plasma is opti-cally thin (optical depth∝ neTe) or above the cut-off density. The left panel of figure 2 showsmeasured and modeled ECE temperatures (keV) and the corresponding residuals weighted withthe measurement uncertainties (dimensionless). Forρpol > 0:995 the plasma is optically thinand, therefore, the data are masked out gradually by increasing the measurement uncertaintiescorrelated with the optical depth (for large data uncertainties the residuals become very small).IDA allows to mitigate corrupted data automatically exploiting diagnostic interdependencies.The temperature and density profiles are parameterized with spline polynomials which easilyallows to determine profile gradients. The right panel of figure 2 shows electron temperature,density, and pressure gradients. Although the temperature and density gradients peak at aboutthe same position (ρpol = 0:991), the peak of the pressure gradient is shifted inwards. Again,the gradient uncertainties ofTe andpe are large in the region where the plasma is optically thin.Another beneficial property of the combined analysis of different diagnostics is the flexibletreatment of different coordinate systems. As the diagnostics measure at different poloidal and36th EPS 2009; R.Fischer et al. : Multiple diagnostic data analysis of density and temperature profiles in A... 2 of 43.328 3.33 3.332 3.334 3.336time (s)05001000Te (eV)3.328 3.33 3.332 3.334 3.336time (s)0246n e (1019 m−3 )3.328 3.33 3.332 3.334 3.336time (s)0510p e (kPa)3.342 3.344 3.346 3.348 3.35time (s)05001000Te (eV)3.342 3.344 3.346 3.348 3.35time (s)0246n e (1019 m−3 )3.342 3.344 3.346 3.348 3.35time (s)0510p e (kPa)3.325 3.327 3.329 3.331 3.333time (s)0200400600800Te (eV)3.325 3.327 3.329 3.331 3.333time (s)02468n e (1019 m−3 )3.325 3.327 3.329 3.331 3.333time (s)0510p e (kPa)Figure 3: Temporal evolution of electron temperature, density and pressure profiles for differentmagnetic coordinatesρpol= 0:88 1:09 in steps of 0.01. Three different shots without (#23226,upper panel), with moderate (#23219, 4 1021 s 1, middle panel), and large (#23225, 91021 s 1, lower panel) D2 fueling rates are shown.toroidal positions in the plasma a common coordinate system has to be used (ρpol). Equilibriumcalculations with temporal resolution of 1 ms are used to map the spatial coordinates of theLIB, DCN and TS channels and the spectral ECE channels on a common coordinate. Due touncertainties in the determined equilibrium and due to uncertainties in the calibrated diagnosticschannel positions flexibility in the mapping procedure is necessary. This flexibility is quantifiedby a factor which scales the coordinates of the various diagnostics. The combined analysisallows to determine these scale parameters together with the profile parameters from the data.Typical scale factors of 1.01 between TS and ECE/LIB are observed which corresponds to ashift of 5 mm at the separatrix. To reduce the uncertainty of the separatrix position additionalinformation such as temperature constraints at the separatrix has to be provided. The following36th EPS 2009; R.Fischer et al. : Multiple diagnostic data analysis of density and temperature profiles in A... 3 of 4results are obtained without the TS diagnostics because the sampling frequency of about 0.1kHz is small compared to the sampling frequencies of LIB (20 kHz), ECE (31 kHz), and DCN(10 kHz) necessary to study the temporal evolution of ELM events and inter-ELM phases.Figure 3 shows the temporal evolution of electron temperature, density and pressure profilesbetween two ELM events forρpol= 0:88 1:09 in steps of 0.01 (thick black trace atρpol= 1:0).The onset of the ELM is indicated by a vertical bar. The three improved H-mode discharges havedifferent D2 fueling rates of 0 (#23226, upper panel), 4 1021 s 1 (#23219, middle panel),and 9 1021 s 1 (#23225, lower panel), respectively. More details about these shots can befound in [2]. Please note that theTe profiles in the shine through region (ρpol > 1:0) have largeuncertainties.Although there is a natural scatter of the ELM behaviour common structures can be identified.After the ELM crash of about 0.7 msne shows a plateau phase of 0.8 ms atρpol = 0:98 1:02 and a fast recovery forρpol < 0:97 within about 1.5 ms. Typically, thene plateau is morepronounced with gas fueling. After the fast recovery with a steepening of thene gradient thereis a distinct difference in thene evolution without and with gas fueling. Without gas fueling(upper panel) thene gradient is continuously increasing up to 6 ms after the ELM onset. Withgas fueling after the complete recovery at the pedestal top (3 ms) there is an extra steepeningafter about 4 ms atρpol = 0:98 1:00. This significant difference is frequently observed anddocumented with ELM averaged profile evolutions of density and density gradients in [2].The temperature profiles show a similar evolution with an ELM crash (0.7 ms), a plateauphase (0.8 ms), a fast (0.4 ms) and slow (3 ms) recovery phase. Typically, the earliest and mostpronouncedTe crash is betweenρpol = 0:96 1:00 where also the fastestTe recovery appears.The pronounced extra steepening with gas fueling after about 4 ms cannot be observed inTe.The ELM crash is most pronounced in the pressure profiles. Please note that theρpol = 1:0trace is at about 1 kPa. The plateau region and the fast and slow recovery phases can be clearlyseen for all discharges. Additionally, the extra steepening inne after 4 ms is also seen inpe.References[1] R. Fischer, E. Wolfrum, J. Schweinzer, and the ASDEX Upgrade Team. Probabilisticlithium beam data analysis.Plasma Phys. Control. Fusion, 50:1–26, 2008.[2] E. Wolfrum, A. Burckhart, R. Fischer, N. Hicks, C. Konz, B. Kurzan, B. Langer, T. Püt-terich, and ASDEX Upgrade Team. Investigation of inter-ELM pedestal profiles in ASDEXUpgrade. InProc. of the 36th EPS Conference on Plasma Physics and Controlled Fusion.Europ. Phys. Soc., Montreux, 2009.36th EPS 2009; R.Fischer et al. : Multiple diagnostic data analysis of density and temperature profiles in A... 4 of 4

Multiple diagnostic data analysis of density and temperature profiles in ASDEX Upgrade

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Multiple diagnostic data analysis of density and temperature profiles in ASDEX Upgrade

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