Ultra high vacuum elastomer seal

A seal for an ultra high vacuum joint comprising:

• A first flange having a first planar surface portion and a second flange having a second planar surface portion, said first and second planar surface portions being closely spaced apart to form a narrow gap between said first and second flanges;
• said first and second flange planar surfaces each having a curved surface indentation having a first and second volume respectively, said first and second volume forming a seal cavity having a third volume when said first and second flange planar surfaces are aligned and brought toward each other, said seal cavity having curved internal surfaces having a surface smoothness on the order of 4 microinches or better;
• a sealing O-ring material having a fourth volume when in a relaxed state, said sealing O-ring material being in said seal cavity in contact with said internal surfaces, said sealing material having an outer surface with a curve conforming to said seal cavity internal surfaces over substantially the entire internal surfaces of said seal cavity wherein said third volume is less than said fourth volume;
• and
• said first and second flanges being positioned with respect to each other so that said sealing material is compressed therebetween, wherein said first and second flange and said sealing material form an isolated chamber in which said ultra high vacuum can be maintained.