Ion cyclotron resonant frequency (ICRF) induced impurity production has raised many concerns since ITER proposed to change the first wall material from beryllium to tungsten. Enhanced DC plasma potential ( V _DC ) due to radio frequency (RF) sheath rectification is well known as one of the most important mechanisms behind the RF induced impurities. Our previous work (Lu et al 2018 Pla... https://thebrickes.shop/product-category/ottoman-with-storage/