Patent ID: 7947965

Claim:
An ion source for generating negatively charged ions, said ion source comprising: a closure plate, with an outlet opening provided therein, a wall defining a combustion chamber, wherein the wall includes a tubular section that extends from the outlet opening and is formed from an insulator material, and a rear wall, said rear wall being disposed at an end of the tubular section opposite the outlet opening and closing off the combustion chamber, a coupling coil including windings that are arranged around the tubular section of the wall outside the combustion chamber, and a filter field magnet disposed adjacent the outlet opening, said filter field magnet being configured such that field lines of the filter field magnet run transversely with respect to an extension direction of the tubular section, said rear wall is being formed from an insulator material and including an inlet opening, and said filter field magnet being disposed on a side of the tubular section remote from the combustion chamber.