Density profile evolution on EAST tokamak by the polarimeter/interferometer system

An 11-channel POlarimeter/INTerferometer (POINT) system with high time resolution (1 μs) was built in 2015 to measure the accurate line-integrated electron density and Faraday rotation angle on the EAST tokamak. An improved density profile reconstruction method was developed based on the POINT measurements to provide accurate density profiles. Furthermore, the pedestal factor from reflectometry data statistics was also introduced. The accuracy of this method is discussed thoroughly. Based on this method, the evolution of the density profile with much higher time resolution than Thomson scattering system can be obtained. These will make for a better understanding of the formation of the internal transport barrier (ITB) on the EAST tokamak.