Experimental observation of enhanced plasma potential due to unabsorbed fast wave on EAST

An experiment on EAST is used to study the fast wave rectification by only an actively powered I-port antenna. The plasma potential up to 100 V was found in the region that does not map along the magnetic field line to active I-port antenna. This enhancement correlates with the local fast wave intensity. An increase in the loading resistance and heating efficiency was observed at a low parallel wave number. The higher heating efficiency is seen to cause lower unabsorbed fast wave power in the SOL regions. This can cause a decrease in the fast wave field intensity that reaches plasma facing components and can result in a decrease in the plasma potential and slow wave intensity.