In one embodiment, a method for cooling a reaction effluent gas includes feeding a sufficient amount of a suitable silicon source cooling gas into a stream of the reaction effluent gas, wherein the reaction effluent gas is produced by a thermal decomposition of at least one silicon source gas in a reactor, and wherein sufficient amount of the suitable silicon source cooling gas is defined based a concentration of the at least one chemical species in the reaction effluent gas; cooling the reaction effluent gas to a sufficient temperature so that: the cooled reaction effluent gas is capable of being handled by a material that is not suitable for handling the reaction effluent gas.