Abstract: In a method for depositing particles onto a substrate a flow of gas containing particles is provided along a flow path that bypasses a deposition chamber. The flow path may direct the flow of the gas containing the particles to a vacuum. To deposit particles onto a substrate in the deposition chamber, the flow path of the gas containing the particles is diverted into the deposition chamber so that particles are deposited onto the substrate. After a desired amount of particles have been deposited onto the substrate, the flow path of the flow of the gas containing the particles is changed to the flow path that bypasses the deposition chamber. A particle deposition system and a method for maintaining particle diameter during deposition of particles onto a substrate also are described.