Experimental study of FIR laser interferometer and density ramping on EAST tokamak

A single-channel far-infrared(FIR) laser interferometer is developed for measuring the line averaged electron density(R=1.82m) of the main plasma on EAST tokamak.While main plasma density is raised by gas puffing,three different divertor regimes,i.e.,low recycling(low divertor plasma density,high temperature),high recycling(high divertor plasma density,low temperature),and detached divertor plasma(low divertor plasma density,low temperature),are first obtained on EAST tokamak.The physical phenomena of these regimes on EAST tokamak are presented briefly.