AbstractPilot calculations have been performed to study the effect of surrounding plasma on several doubly excited states for a few astrophysically important, highly stripped ions of helium isoelectronic sequence Al11+, Si12+, P13+, S14+, and Cl15+. The transitions from 1s2:1Se → 2s2:1Se, 2p2:1De, 2s2p:1Po, 2s3d:1De and 2p3d:1Fo are studied. The effect of the plasma background is taken care of using the Debye screening model which admits of a wide variety of plasma conditions. Transition energies as well as the analytical wave functions of the doubly excited states have been obtained from a study of the pole positions of the collective oscillation modes in the two‐electron charge cloud under a time‐dependent harmonic perturbation. The response properties of the system are analyzed from the linearized version of a suitably constructed variational functional. Most of the calculated data are new. Our results agree well with the relatively few existing experimental and theoretical data for the free ions. The general trend of the results show systematic behavior with respect to increased plasma strength, and the data may be useful from the astrophysical viewpoint. The doubly excited state wave functions have been used to calculate the Coulomb repulsion integrals to check their consistency and may be useful for evaluating other physical properties connected with transitions and also estimating the rate coefficients for dielectronic recombination processes, which play a major role in the diagnostic determination of high‐temperature plasmas. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005