Time-of-Flight Neutral Mass and Velocity Spectrometer for Atmospheric Research
Abstract
The information of the velocity distribution of the neutral gas in the Earth's upper atmosphere is important to understand the non-thermal escape processes and dynamics of tenuous gas in the thermosphere. We have developed a prototype time-of-flight (TOF) neutral gas mass spectrometer (NMS) that simultaneously measures the density and the velocity distribution function of each mass species, using the time-of-flight and the 2D spatial distribution of the ionized particles on a micro channel plate (MCP) detector. The neutral gas is ionized by an electron pulse and then accelerated toward the detector by an electric field that is applied shortly after the ionization pulse. The TOF of the detected particle defines the mass selection and the 2D spatial distribution on the detector yields the velocity distribution, temperature, and bulk velocity of the selected neutral species. In order to preserve the initial velocity of the neutral gas, the acceleration electric filed is applied in the direction perpendicular to the incident gas velocity. We confirmed the feasibility of measuring the velocity distribution of room-temperature Ar (300 K) in a vacuum chamber using our prototype instrument. We will discuss the limitation of these measurements and strategies to mitigate the limitations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.A41B0038F
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- 5407 Atmospheres: evolution