IMPROVEMENTS IN AND RELATING TO THE CONTROL OF IONS

摘要

A guide apparatus includes a vacuum compartment provided at a background pressure and having a gas inlet opening arranged for jetting a gas in the form of a free jet stream containing entrained ions into a vacuum chamber along a predetermined jetting axis. At least one duct housed within the vacuum chamber has a guide bore positioned coaxially with the jetting axis for receiving the free jet stream such that a supersonic free jet is formed in the duct with a jet pressure ratio P1/P2 restrained to a value that does not exceed (A/a)3 to form a subsonic laminar gas flow inside of the duct for guiding the entrained ions, where P1 is the pressure at an exit end of the gas inlet opening, P2 is the background pressure, A is the cross sectional area of the bore, and a is the cross sectional area of the gas inlet opening.

主权项

1. A guide apparatus comprising: a vacuum compartment provided at a background pressure and having a gas inlet opening arranged for jetting a gas in the form of a free jet stream containing entrained ions into a vacuum chamber along a predetermined jetting axis; and at least one duct housed within the vacuum chamber and having a guide bore positioned coaxially with the jetting axis for receiving the free jet stream such that a supersonic free jet is formed in the duct with a jet pressure ratio P1/P2 restrained to a value that does not exceed (A/α)3 to form a subsonic laminar gas flow inside of the duct for guiding the entrained ions therealong, where P1 is the pressure at an exit end of the gas inlet opening, P2 is the background pressure, A is the cross sectional area of the bore, and a is the cross sectional area of the gas inlet opening.