Spherically confined two-electron atoms immersed in Debye plasma

The effect of spatial confinement in the presence of plasma environment on the dipole allowed transition properties for the first five helium-like atoms (He through C4+) is studied. The Debye screening describes the effect of plasma. Additionally, the effect of a spatial confinement (as, for example, it is in the case of atoms surrounded by liquid helium) is described by locating the atom in the center of a spherical box. Time-dependent variation perturbation theory is applied to estimate the orbital energies, polarizabilities, transition energies, oscillator strengths, and transition probabilities. The effect of spatial confinement in the plasma environment shows interesting features. The decrease of the radius of confinement exerts pressure within the system and produces instability in the energy values ultimately ionizing the system. The ionization pressures at different plasma screenings are estimated. The ionization pressure at zero Debye screening for helium agrees with existing data.