Time-of-flight neutral mass and velocity spectrometer for atmospheric research

We have developed a prototype time-of-flight neutral gas mass spectrometer that simultaneously measures the density and the velocity distribution function of each mass species, using the time-of-flight and the two-dimensional spatial distribution of the ionized particles on a charge-coupled device (CCD). We confirmed the feasibility of the velocity distribution measurement in a vacuum chamber using room-temperature Ar gas, by measuring the spatial distribution of the ionized Ar on the CCD and inferring the corresponding velocity distribution of the incident Ar. (C) 2002 American Institute of Physics.