Application of the Magnetic Surface Based PARK-Matrix Method in the HCOOH Laser Interferometry System on HL-2A**supported by the National Magnetic Confinement Fusion Science Program of China (No. 2014GB109001), and National Natural Science Foundation of China (Nos. 11505053 and 11275059)

Abstract

A new electron density profile reconstruction procedure based on the PARK-matrix method has been firstly exploited for the multi-chord formic acid (HCOOH, λ=432.5 μm) laser interferometry system on the HL-2A tokamak. According to the geometric coordinates of the magnetic surfaces reconstructed by the CF (current fitting) code and the assumption that the electron density between two adjacent magnetic surfaces is a constant, the local electron density is calculated layer by layer, and the electron density profile ne(Z) can be determined, as well as the density profile ne(R). The simulation result indicates that the error of the PARK-matrix method is acceptable for the four-chord HCOOH laser interferometer. In the applications, it shows that the reconstructed electron density profile agrees well with the microwave reflectometry measurement, and the sawtooth reversion radius is consistent with that deduced from the soft X-ray signals. Meanwhile, the electron density profiles with electron cyclotron resonance heating (ECRH) and supersonic molecular beam injection (SMBI) are also reconstructed and analyzed.