Experimental scaling of divertor heat and particle flux widths in EAST L-mode plasmas

Abstract

The scalings of divertor heat and particle flux widths have been systematically performed on the Experimental Advanced Superconducting Tokamak (EAST) in radio-frequency (RF) heated L-mode plasma regime under various divertor configurations. The widths were calculated from the measurements of divertor Langmuir probe (LP) arrays and the reciprocating LP diagnostic on the low-field side. A strong inverse scaling of particle and heat flux widths with plasma current Ip (equivalently the poloidal field Bp) has been demonstrated. The measurements of divertor LPs show that the power decay length exhibits λq,div=4.97Ip−0.94 (λq,div=1.46Bp−1.15), in good agreement with the particle decay length λjs=4.74Ip−1.02 (λjs=1.34Bp−1.21). Similar trend measurements have also been demonstrated by the reciprocating LPs. In addition, the scaling with Ip (Bp) appears to be insensitive of the divertor configurations in EAST. The study of heat and particle flux width scaling in EAST is useful for the extrapolation to the future tokamaks such as ITER.