Effect of Ion‐Neutral Collisions on the Plasma Sheath in the Presence of Surface‐Produced Negative Ions

ABSTRACT The effect of ion‐neutral collisions on the plasma sheath has been investigated for electronegative plasma in the presence of surface‐produced negative ions. Such sheath structures are commonly found in the negative ion sources. It has been found that ion‐neutral collisions reduce the ion velocity towards the sheath and consequently reduce the negative ion production from the surface. The space charge profile shows peak near the sheath edge in contrast to the common case where it has a peak near the wall. The fractional loss of the ions at the wall along with the ion impact energy is calculated.