Abstract: A centrifugal pump having a barrel casing and at least one stage casing therein includes a transition from the last stage casing to the pressure connector of the barrel casing in the form of a spiral flow space. The contour of the spiral flow space is formed by a contour of the last stage casing, a contour of a cover which closes the barrel casing on an end face, and an inner contour of the barrel casing.

Abstract: An aperture device (31) is described, which is attachable to a lens system (13). The lens system (13) is arranged to form a particle beam of charged particles, emitted from a sample surface (Ss). The aperture device (31) comprises an end surface (S) which is to be arranged facing the sample surface (Ss), at least one aperture (38) arranged in the end surface (S), a length axis (32) which extends through the centre of said at least one aperture (38), and at least one gas outlet (10), which is arranged at a transverse distance (T) perpendicular from the length axis (32), and is arranged to direct gas into a volume between at least one aperture (38) and the sample surface (Ss). The end surface (S) within a distance, equal to ? of the transverse distance (T), perpendicular from the length axis (32) has a variation along the length axis (32) being smaller than ? of the transverse distance (T).

Abstract: A centrifugal pump having a barrel casing and at least one stage casing therein includes a transition from the last stage casing to the pressure connector of the barrel casing in the form of a spiral flow space. The contour of the spiral flow space is formed by a contour of the last stage casing, a contour of a cover which closes the barrel casing on an end face, and an inner contour of the barrel casing.

Abstract: An aperture device (31) is described, which is attachable to a lens system (13). The lens system (13) is arranged to form a particle beam of charged particles, emitted from a sample surface (Ss).The aperture device (31) comprises an end surface (S) which is to be arranged facing the sample surface (Ss), at least one aperture (38) arranged in the end surface (S), a length axis (32) which extends through the centre of said at least one aperture (38), and at least one gas outlet (10), which is arranged at a transverse distance (T) perpendicular from the length axis (32), and is arranged to direct gas into a volume between at least one aperture (38) and the sample surface (Ss). The end surface (S) within a distance, equal to 1/3 of the transverse distance (T), perpendicular from the length axis (32) has a variation along the length axis (32) being smaller than 1/6 of the transverse distance (T).

Abstract: A centrifugal pump with a housing having one or more impellers having an axial or semiaxial, open or closed design disposed therein and an intake channel mounted upstream of the first impeller. A plurality of grooves that are distributed around the circumference and extend in the direction of flow are arranged within the wall area of the intake channel. In the housing wall of the intake channel there is a closed annular wall area constructed between a point of entry of the first impeller and the proximate ends of the grooves, whereby the grooves are operatively connected exclusively with the space in the intake channel.

Abstract: A centrifugal pump with a housing having one or more impellers having an axial or semiaxial, open or closed design disposed therein and an intake channel mounted upstream of the first impeller. A plurality of grooves that are distributed around the circumference and extend in the direction of flow are arranged within the wall area of the intake channel. In the housing wall of the intake channel there is a closed annular wall area constructed between a point of entry of the first impeller and the proximate ends of the grooves, whereby the grooves are operatively connected exclusively with the space in the intake channel.