Understanding and modeling of gas puff injection for diagnostic purposes

This article presents an experimental setup capable of providing high spatial and temporal resolution measurements of neutral gas puff injection using a glow discharge to excite the neutral gas and an ultra-high-speed camera to record the emitted light. Using the proposed setup, the shape and propagation velocity of a thermal deuterium gas puff at 1 bar have been measured. The cloud has a conical shape and a propagation velocity of vprop = 1870 ± 270 m/s. Furthermore, a code has been developed with the aim of studying the relation between the propagation velocity and the initial injection velocity of the gas. The simulations show that an initial injection velocity in the range of vinj ∼ 1650-1950 m/s can reproduce a propagation velocity of vprop = 1870 ± 270 m/s.