Abstract: An ultra high vacuum (UHV) joint is scaled by an elastomer O-ring (7) between adjacent flanges (3,4), fitting in a seal cavity formed by grooves (41,42) in the flange (3,4) surfaces. The groove surfaces (41,42) are highly polished and shaped such that the O-ring (7) conforms to the groove surfaces (41,42) and contacts them substantially entirely when the flanges (3,4) are clamped together. This improved structure significantly reduces the permeation through and the gas leakage around the seal (7). The resulting seal (7) can support a vacuum of 10.sup.-11 torr or better. The conformal-groove geometry of the present invention can be used with seals other than elastomer seals, such as soft metal seals (55,65).

Abstract: An effusion source, for the generation of molecular beams, adapted to be positioned at an angle to the horizontal, within a vacuum chamber, of an MBE system including heating structures around the source to create uniform temperatures across the source in planes substantially parallel to the horizontal to cause uniform temperatures in planes substantially parallel to the horizontal in materials placed within the source and intended for MBE applications. A number of heating embodiments are described.