An interferometric force probe for beam diagnostics and the study of sputtering

Abstract

Abstract A novel probe for the measurement of forces exerted by a beam of ions and neutral atoms on a small target is described. The force probe is intended for various applications: First, diagnostics of thruster plumes of electric spacecraft propulsion engines, in particular the determination of the spatial distribution of the momentum in an exhaust beam, and second, the study of sputtering of solid targets by means of the related momentum transfer. The instrument makes use of a sensitive cantilever whose elastic deflection is measured interferometrically along two axes and enables that way a simultaneous measurement of two independent components of the force vector. The present contribution focuses on setup and calibration of the probe. Example measurements with obliquely irradiating ion beams are performed.

Keywords

• Sputtering
• Momentum transfer
• Force measurement
• Beam diagnostics
• Electric spacecraft propulsion