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This work presents analytical and numerical results for the pressure field distribution and its gradient along the dipole vacuum chamber of Brazilian light source. The gas transport in the molecular regime is considered a diffusive phenomenon. Mathematical and physical formulations are given and detailed, in special, conductance and throughput are defined in modeling in two dimensions. In addition, a detailed discussion about the boundary conditions is presented, taking account both the steady state outgassing of the walls and transient and localized gas bursts. We will present results for a gas burst in one of the dipole magnets’ vacuum chamber. This approach is applied to realistic conditions, such as diameter and length of the tubes, dimensions of the vacuum chamber and the outgassing rate and throughput of the gas source induced by a certain amount of radiation hitting the walls. This can be considered as a gas source localized in position and in time. We analyze the steady state and the transient cases, and, in particular, the effect of the gas reaching the vacuum chamber and affecting the electron beam. With this study, we can design a dipole vacuum chamber to change the conductance between the vacuum chambers and the tubes, in order to optimize them. |