Development of high energy and high flux argon ion gun

Abstract

BackgroundLarge size aspherical mirrors have been widely used in space communication systems because of their high angular resolution and energy harvesting ability.PurposeThis study aims to develop a high energy and high flux argon (Ar) ion gun for the rapid polishing of modified silicon layer on the surface of large size SiC aspherical mirror.MethodsFirst of all, Ar ionization was realized by filament and anode grid. Ar+ energy was determined by anode voltage whilst the extractor and electrostatic lenses were employed to achieve Ar+ emission and focusing. The high transmittance of argon ions was realized by adjusting the voltage between the filament and the anode grid to maximize the ionization rate, and adjusting the size and relative position of the electrostatic focusing lens. The materials in the Ar ion gun were selected not only suitable for ultra-high vacuum, but also preventing from vacuum discharge. Then, the parameters of the main components of argon ion gun were determined by theoretical calculation and simulation of the trajectory of argon ion beam. Finally, preliminary experimental tests were carried out to verify its performance.ResultsThe test results show that the Ar+ energy and beam flux can reach 20 keV and 50 μA, respectively, at 30 mm working distance and Ar partial pressure of 1.2×10-2 Pa. The beam size can be continuously adjusted from 19 mm to 24 mm.ConclusionsThis developed argon ion gun with small size, high energy and high flux, can be installed on a vacuum multi-dimensional displacement table for a wide range of movement to achieve high vacuum surface polishing of large aperture optical elements.

Keywords

• argon ion gun
• optical mirror polishing
• surface science
• electrostatic focusing lens