In the gas-column code-validation experiments, a shock generator produces a planar shock wave that strikes a column of sulfur hexafluoride gas formed in air within the experimental chamber. Before the gases are piped into the chamber, they can be separately mixed with a fog of microscopic glycol/water droplets to make them visible. Cross sections of the column's density are photographed before the shock wave arrives and at specific times later as the shock wave distorts and breaks up the column. The light source for these photos is a 1-millimeter-thick pulsed laser beam spread into a fan that slices through the gas column about one-third of the way down.