Plasma source assemblies comprising an RF hot electrode having a body and at least one return electrode spaced from the RF hot electrode to provide a gap in which a plasma can be formed. An RF feed is connected to the RF hot electrode at a distance from the inner peripheral end of the RF hot electrode that is less than or equal to about 25% of the length of the RF hot electrode. The RF hot electrode can include a leg and optional triangular portion near the leg that extends at an angle to the body of the RF hot electrode. A cladding material on one or more of the RF hot electrode and the return electrode can be variably spaced or have variable properties along the length of the plasma gap.