Funnel cone for focusing intense ion beams on a target

Abstract

We describe a funnel cone for concentrating an ion beam on a target. The cone utilizes the reflection characteristic of ion beams on solid walls to focus the incident beam and increase beam intensity on target. The cone has been modeled with the TRIM code. A prototype has been tested and installed for use in the 350-keV K + NDCX target chamber.

Nanopatterning by ion implantation through nanoporous alumina masks

“…(a) Within the group of geometry-effects, ''focusing'' of an incident ion beam by a capillary wall is well described in the literature, [28][29][30][31][32] mostly using funnel-shaped glass capillaries of micron-scale exit diameter. Most relevant to our case of periodic alumina masks is the experiment by Stolterfoht et al, 28 in which 3 kV Ne ions are focused by cylindrical pores in a polymer track edge membrane, however, with aspect ratio 100 : 1 and 100 nm pore diameter.…”

“…They find Gaussian angular ion distribution patterns, but no rings, confirmed by other groups. 29 An important aspect is the wall-charging by secondary electron emission, which can effectively channel ions through a long capillary. The only literature hinting at ring patterns is the finding of a ''halo'' surrounding the focused ion spot in ref.…”