Abstract:
Recent models have highlighted the effects of shock-focusing in a spherically symmetric collapsing cavity. Several of these simulations have predicted extremely high temperatures in the final stages of the collapse. In order to investigate the feasibility of such a mechanism, an idealized one-dimensional experiment was designed in which a shock wave was introduced by a piston launched from a gas gun into a closed cylindrical cavity. The compressed gas contained within had a quantity of argon introduced. Light was monitored using a fast photodiode and a gated spectrometer capable of resolving nanosecond duration pulses. The piston motion was measured by streak and framing photography using an Ultranac high-speed camera. A threshold in light emission was observed at a piston velocity of ca. 20 m s[sup -1]. It is shown that the light emission shows some of the features of the observed luminescence. The effects of colliding waves are discussed.