A source assembly (4, 300, 400, 620) configured to couple to a vacuum chamber of an instrument (30, 610) comprising a first pin and a second pin extending radially from the instrument (30, 610), the source assembly (4, 300, 400, 620) comprising: a moveable component (220, 320, 420, 530, 730, 1210) comprising a circumferential slot; a stationary component (210, 310, 410, 510, 720, 1220) coupled to the moveable component (220, 320, 420, 530, 730, 1210) and comprising an ion source or an electron source, in which the ion source or the electron source comprises a plurality of lenses (130, 140, 150); in which the stationary component (210, 310, 410, 510, 720, 1220) further comprises a slot that is configured to receive the first pin and the second pin of the instrument (30, 610) into the slot of the stationary component to align the ion source or the electron source in the instrument (30, 610) when the first pin and second pin engage the slot of the stationary component; in which the moveable component (220, 320, 420, 530, 730, 1210) is configured to provide an axial force to the stationary component (210, 310, 410, 510, 720, 1220) upon rotational movement of the moveable component (220, 320, 420, 530, 730, 1210) in a first direction and release the axial force upon movement of the moveable component (220, 320, 420, 530, 730, 1210) in a second direction opposite the first direction; and in which rotational movement of the moveable component (220, 320, 420, 530, 730, 1210) in the first direction is configured to engage the second pin in the circumferential slot of the moveable component (220, 320, 420, 530, 730, 1210) to lock the stationary component (210, 310, 410, 510, 720, 1220) in place and compress a spring to thereby provide a substantially fluid tight seal between the source assembly (4, 300, 400, 620) and the vacuum chamber. a moveable component (220, 320, 420, 530, 730, 1210) comprising a circumferential slot; a stationary component (210, 310, 410, 510, 720, 1220) coupled to the moveable component (220, 320, 420, 530, 730, 1210) and comprising an ion source or an electron source, in which the ion source or the electron source comprises a plurality of lenses (130, 140, 150); in which the stationary component (210, 310, 410, 510, 720, 1220) further comprises a slot that is configured to receive the first pin and the second pin of the instrument (30, 610) into the slot of the stationary component to align the ion source or the electron source in the instrument (30, 610) when the first pin and second pin engage the slot of the stationary component; in which the moveable component (220, 320, 420, 530, 730, 1210) is configured to provide an axial force to the stationary component (210, 310, 410, 510, 720, 1220) upon rotational movement of the moveable component (220, 320, 420, 530, 730, 1210) in a first direction and release the axial force upon movement of the moveable component (220, 320, 420, 530, 730, 1210) in a second direction opposite the first direction; and in which rotational movement of the moveable component (220, 320, 420, 530, 730, 1210) in the first direction is configured to engage the second pin in the circumferential slot of the moveable component (220, 320, 420, 530, 730, 1210) to lock the stationary component (210, 310, 410, 510, 720, 1220) in place and compress a spring to thereby provide a substantially fluid tight seal between the source assembly (4, 300, 400, 620) and the vacuum chamber.