High performance micropane electron beam window

Abstract

A silicon disk etched so that it contains a multitude of microscopic and thin window panes (micropanes) can potentially transmit a larger average electron beam current density and absorb a smaller fraction of the beam energy than a common metal foil window. The enhanced performance is achieved by a combination of decreased power loss due to the extremely small window thickness (∼1 μm), and increased conductive cooling due to the small diameter (∼50 μm) of the micropanes and the large cross section of the honeycomb structure that supports the micropanes. Beam current densities up to 34 A/cm2 are permitted within each micropane. When integrated over many micropanes across the face of a window, average current densities up to 1 A/cm2 are permitted—at least three orders of magnitude larger than the <mA/cm2 typical of foil windows. The small mass thickness yields high transparency, even for low energy beams. The transmission efficiency for a 100 keV beam is 99.5.