To connect vacuum chambers without the need of bolted flanges in an environment which forbids direct human access extra large pillow seals have been developed. They seal only by pressing an inflatable foil pillow against a polished metal surface. The two halves of a pillow seal are connected with a bellow in the middle, when inflated the bellow expands and the two plates with their foil pillows press againt thei well polished counterpart. Then a pillow seal fills the whole gap between two neighboring vacuum chambers.
Like all removable inserts in the target area the pillow seals are mounted on shielding plugs to make hands-on maintenance possible for the connections on top. Because of the wide area the primary beam can cover after a dipole magnet some pillow seals have an open aperture of up to 1200mm wide and 148mm high, others are round with 200mm or 500mm diameter.