An epitaxial deposition chamber having an upper cone for controlling air flow above a dome in the chamber, such as a high growth rate epitaxy chamber, is described herein. The upper cone has first and second components separated by two or more gaps in the chamber, each component having a partial cylindrical region having a first concave inner surface, a first convex outer surface, and a fixed radius of curvature of the first concave inner surface, and a partial conical region extending from the partial cylindrical region, the partial conical region having a second concave inner surface, a second convex outer surface, and a varying radius of curvature of the second concave inner surface, wherein the second concave inner surface extends from the partial cylindrical region to a second radius of curvature less than the fixed radius of curvature.