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U.S. Department of Energy
Office of Scientific and Technical Information

Electrostatic lens to focus an ion beam to uniform density

Patent ·
OSTI ID:862744

A focusing lens for an ion beam having a gaussian or similar density profile is provided. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to a uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
Assignee:
United States of America as represented by United States Energy (Washington, DC)
Patent Number(s):
US 4002912
OSTI ID:
862744
Country of Publication:
United States
Language:
English