Velocity Distribution of $\hbox{H}^{-}$ Ions in Low Temperature Hydrogen Plasma
A Monte Carlo solution of the Boltzmann equation is applied to the calculation of the velocity distribution of negative atomic ions H- in uniform H/H2 plasmas in a wide parameter range. Results are shown for the energy distribution n(epsiv), the 2-D velocity distribution, and the energy-dependent coefficients of the spherical harmonics expansion of its angular part, for different values of the reduced electric field E/N, the atomic fraction, and the H+ mole fraction. By increasing E/N or the atomic fraction at constant ion energy, the velocity distribution becomes highly anisotropic, and at same time, n(epsiv) features a suprathermal tail consistent with analytical results.
Momentum transfer Cs+/H2 cross section from an inversion of transport data
Monte Carlo (MC) calculations of Cs+ transport in H2 are performed in order to establish a reliable transport cross section for momentum transfer. This system is important for plasma modeling in the context of the negative ion source design proposed for plasma heating in future nuclear fusion reactors. Two procedures are checked: use of the Langevin approximation based on realistic values of the physical parameters and a purely statistical, multi-parameter function allowing for shape variation at relative high energy. The two alternatives are discussed and final results provided to be used for negative source modeling.
Solitary Orbital Paget Disease: A Case Report
Purpose: To describe the clinical findings in a patient who had developed painless supraorbital prominence. Methods: Clinical and histopathological findings of the case are reviewed and presented. Results: The patient had an isolated histologically confirmed Paget disease of the orbit. Local excision of the lesion was performed. Conclusion: Paget disease can present not only as a diffuse process but also as a painless, solitary lesion of the orbit.