Schematic figure of the sMSE set-up at ASDEX Upgrade. NBI: Neutral beam injector; M: mirror; W1 and W2: cover and vacuum windows; L1, L2, and L3: lens systems; PEM1 and PEM2: photo-elastic modulators; P: polarizer; CCD: charge-coupled device; : magnetic field; : beam velocity; : Lorentz field; : direction of line of sight.
Top plot: Experimental data from the ASDEX Upgrade beam emission spectrum D (bold line), modelled spectrum d (dashed line), consisting of D CX component (square), D MSE + D Imp line (diamond), D FIDA (circle), D CT (x), D Bg line (grey). The filled area represents the calculated MSE spectra for the full (blue), half (red), and third (green) energy component. Bottom plot: χ as a measure for the goodness-of-fit.
Schematic flow-chart representing the forward model of sMSE measurements and the fit to experimental data. : magnetic field; : beam velocity; : Lorentz field; T p : Stark line ratio; : local emission coefficient-dependent on wavelength (λ), polarization state (pol), and spatial position ( ). The modelled data are fitted to experimental data. The modelled data describing the beam emission are fitted to experimental data detected by the CCD-chip (color coded plot).
(a) Comparison between the multi-Gaussian based simplex model, the forward model and the extended forward model, latter regarded for its components separately (d (1), d (2) = d (1) + quadratic dispersion, d (3) = d (2) + d CT , d (4) = d (3) + separated width for each beam energy component, d (5) = d (4) + deviation term for variation in beam direction, d (6) = d (5) + d FIDA, d (7) = d (6) + boundary conditions) for three different channels. (b) At the right table the number of free parameters, f i , considered in ( ) is outlined for each model.
Results of the error analysis of the MSE spectrum (grey-color coded is the log-likelihood l-normed with respect to maximum (l/l max )−1).
Correlation analysis T p and E L (grey-color coded is the log-likelihood l-normed with respect to maximum (l/l max )−1).
sMSE results: Time traces for the measured Lorentz field E L and the apparent polarization ratio (third and fourth rows) for two ASDEX Upgrade shots (sMSE observed on NBI3) and a detailed view of the quantities of interest with exponential fit for the temporal evolution (lower panel). Time traces of the port-through power of applied heating sources is shown in the first row, the second row shows the central electron temperature (T e ) and density (n e ) (IDA 21 ) along with ion temperature measurements (T i ) from charge exchange recombination spectroscopy.
Pressure change for heating scenario transition of TON: before and after NBI5 on (black curves) and TOFF: before and after switching NBI5 off (grey curves) obtained from the fitted Lorentz field (bold lines with circle-like symbol) and from kinetic measurements (dashed lines) for different radial positions.
Radial profile of fitted Lorentz field during high power phase (black curve) and after high power phase (grey curve). The radial shift of the magnetic axis for these time points is shown by the vertical lines in the same color.
Comparison of a set of time traces of the fitting parameter E L (bold line with circle-like symbol) with the outcome of the CLISTE equilibrium code for three different radial positions (bold line).
Radial profile of polarization fraction (upper subplot), equilibrium result for pitch angle in MSE geometry γCl (middle subplot), and safety factor q (lower subplot) during high power phase (black curve) and after high power phase (grey curve). The radial shift of the magnetic axis for these time points is shown by the vertical lines in the same color.
Schematic representation of sensitivity of on the magnetic field. LOS: Line of sight; : Lorentz field; θ1, 2: observation angle on Lorentz field; π1, 2 and σ1, 2: polarization characteristic of π- and σ-polarized light; : velocity of beam particles.
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