Abstract: A microwave window structure for a low-pressure chamber is provided. The window structure enables microwave energy to be introduced into the chamber from a source external to the chamber. The window structure includes a fixture having electrically conductive walls. Inner portions of the walls provide a peripheral region of an aperture within such fixture. The fixture is adapted for mounting to a sidewall portion of the chamber. A solid, microwave energy transparent dielectric window is included. The window includes: a periphery portion affixed to the fixture; and, an inner region disposed within the aperture of the fixture.