Measurement of Absolute Carbon Ion Density Profile Based on CXRS Diagnostic on HL-2A Tokamak

The profile of absolute carbon ion density is calculated based on the charge exchange recombination spectroscopy (CXRS) diagnostic on HL-2A tokamak. The carbon ion concentration is derived by a combination of absolutely calibrated active spectrum intensity, neutral beam densities and effective charge exchange emission rates. The neutral beam densities for the full (Eb), one-half (Eb/2) and one-third (Eb/3) fractional beam energy components are calculated with the beam attenuation process which is determined by the beam stopping cross-section. The beam population of H∗(n=2) to H(1s) is evaluated, both of which contribute to the charge exchange procedure as donors. Zeff profiles measured by the local impurity concentration and visible bremsstrahlung are compared.