A gas diffuser unit for a process chamber includes at least one controllable diffuser, a power source, and a controller. The at least one controllable diffuser is configured to generate controllable forces acting in various directions on a gaseous material in a flow of the gaseous material introduced into the process chamber, to spread the gaseous material inside the process chamber. The power source is coupled to the at least one controllable diffuser, and configured to supply power to the at least one controllable diffuser to generate the controllable forces. The controller is coupled to the power source and configured to control the power supplied by the power source to the at least one controllable diffuser.