A valve unit configured for a charged particle beam device having a beam path 2 is described. The valve unit includes a vacuum sealed valve housing 102 configured for a pressure difference between the inside of the valve housing and the outside of the valve housing, wherein the housing provides a beam path portion 103 for having a charged particle beam pass therethrough along the beam path, a valve positioning unit adapted for selectively providing a first movement of the valve housing such that the beam path portion is selectively moved into and out of the beam path, and at least one sealing element 122 configured for a second movement, wherein the second movement is different from the first movement.