Recovery of Ion Parameters from NPA Measurements on TCV

plasmas has been developed by modelling the measured energy spectra of the neutral deuterium fluxes varying the parameters of the T i profile. A Neutral Particle Analyser (NPA) [1,5] is used on the TCV tokamak [2] to measure the energy spectrum of hydrog en and deuterium neutrals escaping the plasma. A Kinetic Transport Algorithm, (KN1D) [3], was applied to obtain neutral density profiles in the bulk plasma. The response of Charge eXchange energy spectra to plasma parameters was examined with a model prediction. Ion temperature profiles, evaluated by this method, were compared with the classical logarithmic CX-spectrum slope evaluation. Results based on analysis of NPA data were also compared with measurements from charge exchange recombination spectroscopy (CXRS) [4]. TCV [2] is a medium-sized tokamak (R=0.88 m, a=0.25 m, Ip < 1 MA, BT < 1.54 T, plasma elongation 1-2.8) able to produce a plasma with the central electron density 0.5 -15×10 19 m -3 , an electron temperature over 10 keV with bulk central ion temp eratures 0.3-1 keV. A 5 -channel NPA, with electrostatic energy separation [1], measures the ion parameters [5-7]. The NPA voltage sweeps the energy channels to measure neutral particle energies in the range of (0.6 →6.5 keV), with a time resolution of ≥13 ms viewing the plasma along a vertical chord (fig.1). CX spectrum and ion temperature. The energy spectrum of passive atomic flux J(E) traversing the plasma surface and entering the external instrument (NPA) is the sum of fluxes in the plasma column along the view line of the analyser [8]