Monte Carlo neutral density calculations for a bumpy torus

The steady-state nature of the ELMO Bumpy Torus (EBT) [J. Vac. Sci. Technol. 18, 1088 (1982), and references therein] plasma implies that the neutral density at any point inside the plasma volume determines the local particle confinement time. This article describes a Monte Carlo calculation of three-dimensional atomic and molecular neutral density profiles in EBT. The calculation has been done using various models for neutral source points, for launching schemes, for plasma profiles, and for plasma densities and temperatures. Calculated results are compared with experimental observations—principally spectroscopic measurements—both for guidance in normalization and for overall consistency checks. Implications of the predicted neutral profiles for the fast-ion decay measurement of neutral densities are also addressed.