Boron Nitride Sputter Erosion Measurements by Cavity Ring-Down Spectroscopy (Preprint)
Abstract
Sputter erosion is a critically important process in many electric propulsion (EP) devices from the point of view of both lifetime assessment and contamination effects. In many Hall thrusters erosion of boron nitride (BN) is of primary interest. In this contribution we introduce the use of cavity ring-down spectroscopy (CRDS) as a diagnostic for measurement of sputtered BN. The measurement approach is based upon probing sputtered boron atoms in the region of 250 nm. We report proof of principle CRDS measurements of sputtered boron atoms from both boron and BN targets. The measurements are obtained with pulsed CRDS in a diagnostic chamber consisting of an ion beam incident on the target materials. We also outline the design of a higher sensitivity continuous-wave (cw) CRDS system using the fourth harmonic beam from an external cavity diode laser as the light source. The cw-CRDS system will be used for near real time sputter erosion measurements of thruster devices. Anticipated signal levels and signal-to-noise for the cw-CRDS system are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 06, 2007
- Accession Number
- ADA473501
Entities
People
- Alec D. Gallimore
- Azer P. Yalin
- Lei Tao
- Naoji Yamamoto
- Timothy B. Smith
Organizations
- Air Force Research Laboratory