An embodiment is an apparatus, such as a plasma chamber. The apparatus includes chamber walls and a chamber window defining an enclosed space. A chamber window is disposed between a plasma antenna and a substrate support. A gas delivery source is mechanically coupled to the chamber window. The gas delivery source comprises a gas injector having a passageway, a window at a first end of the passageway, and a nozzle at a second end of the passageway. The nozzle of the gas delivery source is disposed in the enclosed space. A fastening device is mechanically coupled to the gas delivery source. The fastening device is adjustable to adjust a sealing force against the gas injector.