The full spectrum is shown (black) for an Ohmic plasma, (blue) a plasma with only the probing beam (no fast ions moving towards the observer), (green) a plasma during injection of NBI2 with ions moving to the observer but without active CX signal, and (red) with both beams. In the inlay the signal in the fast ion relevant wavelength range is shown. A part of the BES (from , overlapping with a CII multiplet) is seen on the red wing of the line .
Spectra for different acceleration voltages in NBI2 (bremsstrahlung subtracted). The injection energy is changed from 30 (blue) to (red). An Ohmic spectrum (black) and spectrum with only NBI1 (green) are given as reference. Impurity lines overlap with the fast ion spectrum at 15, 22, 32, and .
FP simulation (Ref. 6) for a TEXTOR pulse with both beams injected. The beams are identical but the pitch has opposite sign. The dashed line indicates the pitch of a CXRS line of sight. The full curves enclose the area of velocity space that can contribute to the measured signal at specified energies. Within each of these regions the weighting factors are inhomogeneous (see Refs. 2 and 5).
Fitted spectrum. In order to determine the intensity of the slowing down spectrum, the impurity lines and bremsstrahlung must be fitted simultaneously with the synthetic slowing down spectrum from the FP model. Wavelength abcis is converted to energy scale. The “bumps” seen in the slowing down tail are impurity lines.
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