  We report initial NMR studies of continuous flow laser-polarized xenon gas,
both in unrestricted tubing, and in a model porous media. The study uses Pulsed
Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining
more sophisticated information than just translational self-diffusion
coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized
xenon gas in unrestricted tubing indicate clear diffraction minima resulting
from a wide distribution of velocities in the flow field. The maximum velocity
experienced in the flow can be calculated from this minimum, and is seen to
agree with the information from the complete velocity spectrum, or motion
propagator, as well as previously published images. The susceptibility of gas
flows to parameters such as gas mixture content, and hence viscosity, are
observed in experiments aimed at identifying clear structural features from
echo attenuation plots of gas flow in porous media. Gas-phase NMR scattering,
or position correlation flow-diffraction, previously clearly seen in the echo
attenuation data from laser-polarized xenon flowing through a 2 mm glass bead
pack is not so clear in experiments using a different gas mixture. A propagator
analysis shows most gas in the sample remains close to static, while a small
portion moves through a presumably near-unimpeded path at high velocities.
