Erosion sensor using time-resolved cavity ring-down spectroscopy for Hall thrusters

Development of a Cavity Ring-Down Spectroscopy Sensor for Boron Nitride Erosion in Hall Thrusters

Sputter erosion of boron nitride (BN) is a critically important process in many Hall thrusters from the point of view of both lifetime assessment and contamination effects. This contribution describes the development of a laser based sensor for in situ monitoring of sputtered BN from Hall thrusters. We present a laser electro-optic system and its demonstrative measurement results from BN sputte...

Boron Nitride Sputter Erosion Measurements by Cavity Ring-Down Spectroscopy

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 appr...

Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

A laser-based cavity ring-down spectroscopy (CRDS) sensor for measurement of hydrogen chloride (HCl) has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ ) limit of detect...

Cavity-locked ring-down spectroscopy

The Technical Challenges of using Cavity Ring - Down Spectroscopy to Study Hall

We present the initial results from a cavity ring-down sensor for measuring the density of sputtered boron atoms originating from the discharge channel of a 6-kW Hall thruster. The sensor traps 250 nm light in a high-finesse cavity to greatly increase its sensitivity to boron atoms. Measurements were obtained with the thruster operating at seven conditions spanning discharge voltages from 150 t...