Rayleigh Scattering Measurement of Neutral Atom Number Density Downstream of an Electric Propulsion

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K14506
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Aerospace engineering
• Research Institution: Kyushu University
• Principal Investigator: YAMAMOTO NAOJI 九州大学, 総合理工学研究院, 教授 (40380711)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 電気推進 / 中性粒子密度計測 / 地上設備の影響 / レイリー散乱 / 光学計測

Outline of Final Research Achievements

Neutral atom number density was measured in high vacuum using the Rayleigh scattering technique, in order to elucidate facility effects on electric propulsion devices. Nitrogen molecular number density was measured to show the validity of the Rayleigh scattering technique. Xenon neutral number density was measured downstream of a miniature Hall thruster. The number density of xenon atoms was estimated to be (4±1.5)×10^19 m^-3 at mass flow rate of 0.2 mg/s. The results are in good agreement with 1D calculations.
We confirmed that using a laser with shorter wavelength and pulse width improved the detection limit.
The present results show that the Rayleigh scattering method will be useful for measurement of the neutral atom number density in the plume region, with further improvement of the detection limit. This method could be used to reveal vacuum facility effects on electric propulsion system performance, and further illuminate the physics behind electric propulsion.

Free Research Field

航空宇宙工学