One-Dimensional Numerical Simulation of Shock Wave Propagation Induced by Vacuum Accidents in a Beamline.

A simulation for shock wave propagation in a vacuum tube has been conducted from the viewpoint of protection from vacuum accidents in beamlines of a synchrotron radiation facility. Inserted devices in beamlines such as absorbers, slits, masks and beryllium windows were replaced with orifices installed in a shock tube as a simulation model. One-dimensional Euler's equations with friction terms were used for estimating the effects on shock wave decay as well as the effects of friction along a tube on shock attenuation. The results indicated that the entrance diameter of the shock tube was an important parameter for determining the strength of shock waves generated by the expansion of gases at the tube entrance and that the friction effects were too large to delay the arrival time of shock waves at the end of a long tube. Moreover, shock wave propagation in a long beamline model based on the MR beamline in the National Laboratory for High Energy Physics was simulated for designing adequate protection from vacuum accidents. The present simulation provides necessary information for the design of a protection system for vacuum accidents in other facilities.