The present disclosure generally relates to a processing system comprising a flow assembly for processing thin substrates using low flow rates. The flow assembly comprises at least one compression part configured to compress a volume occupied by gas radicals flowing at a rate of about 0.1 sim to 5 slm from a plasma source to a chamber in two dimensions. The at least one compression part compresses the volume occupied by the gas radicals about 50% to about 90% from an initial cross-sectional area of the port of the process chamber. In some embodiments, the at least one compression part is a two compression parts, where a first compression part coupled to the port of the process chamber is larger in volume than a second compression part coupled to the first compression part and the chamber. In such an embodiment, the first and second compression parts are removable.