Monte Carlo simulation of gas-sheet targets generated by narrow slits

Ogiwara, Norio

Monte Carlo simulations of a molecular flow regime demonstrate the generation of large-scale gas-sheet targets in a vacuum by two typical gas inlet systems. One inlet system consists of a set of identical narrow rectangular slits; they are placed in rotational symmetry around an axis in a manner such that all the slits have the same plane that is orthogonal to their short sides. This plane divides all the slits into halves. The other inlet system consists of a thin concentric circular slit with a large aperture. In both these systems, gas is introduced from the outside toward the center, leading to the appearance of a large-scale gas sheet around the center. In the case of the circular slit, with inner and outer diameters of 200 and 400, respectively, and a gap of 0.1, the generated gas sheet had a diameter of 130 and thickness of less than 0.4 (half width), where all the valuables are expressed in ratio. The uniformity of the gas density, which is the ratio of the minimum to the maximum peak value of gas density, was more than 85%.