A surface wave plasma source (SWPS) is disclosed, having an electromagnetic (EM) wave launcher including a slot antenna configured to couple EM energy in a desired EM wave mode to a plasma by generating a surface wave on a plasma surface of the SWPS adjacent the plasma. The SWPS also includes a dielectric window positioned below the slot antenna, having a lower surface and the plasma surface. The SWPS further includes an attenuation assembly disposed between the slot antenna and the plasma surface. The attenuation assembly includes a first fluid channel substantially aligned with a first arrangement of slots in the slot antenna, and is configured to receive a first flow of a first fluid at a first fluid temperature. The SWPS finally includes a power coupling system coupled to the EM wave launcher and configured to provide EM energy to the EM wave launcher for forming the plasma.