Hot spots generated by low hybrid wave absorption in the SOL on the EAST tokamak

Lower Hybrid Waves (LHWs) strongly heat the SOL plasma and generate hot spots outside the outer strike point (OSP) in the EAST tokamak. Five pairs of visible strips are separated from the middle plane along the toroidal field, which coincide with the five grills on the LHW antenna. The hot spots becomes stronger when with the distance between the hot spots and the outer strike point decreases. The level of the heat flux at the hot spots is similar to that at the strike point for a short distance of about 10 cm between the OSP and hot spots. During Ar gas puffing, the heat flux at the strike point has been significantly reduced, but the heat flux at hot spots increases of ∼30%. It has been also found that the heat flux at the hot spots and the LHW absorption in the SOL have been reduced in the H-mode compared to the L mode.