Equilibrium ion distribution modeling in RF ion traps and guides with regard to Coulomb effects

Considered is the problem of numerical simulation of the equilibrium ion distributions for ions with different m/z ratios in RF ion traps and guides, in which the ion confinement is due to the averaged RF pseudopotential field and collision cooling. The proposed algorithm takes into account the buffer gas temperature and Coulomb interaction between the particles. The original self-consistent problem for the Poisson equation is reduced to a variational problem for a thermodynamic potential, which is solved numerically basing on the smooth spline approximations and the conjugate gradients method. The algorithm is implemented as a separate program module of the MASIM 3D package and comprehensively tested. Some numerical results are discussed. (C) 2010 Elsevier B.V. All rights reserved.