The APARC group at Queen’s University has long been at the forefront of theoretical and computational advances in atomic structure, and electron & photon collisions with atoms and ions. We use theoretical methods to generate high quality atomic data for use in the study of astrophysical and fusion plasmas. Using this data, we can obtain spectra containing emission or absorption lines, which arise when the atoms and ions present in certain phenomena emit or absorb energy.
While some of the necessary data can be obtained experimentally, they are frequently of insufficient accuracy or limited to a small number of transitions. Computational approaches are the only means by which data of the required quality and quantity can be provided. The calculation of highly accurate atomic physics data is essential to the field of astrophysics and confined plasma physics.
Along with the development of new and existing computational methods work within the group is currently concentrated into two areas:
Atomic data for the Fe-peak elements
Under this theme we consider the calculation of atomic data pertaining to the astrophysically important Fe-peak elements such as Fe II, Fe III, Fe IV, Fe V, Ni II, Ni III, Ni IV, Co II etc. Until recently, the accurate determination of collision data for these ions remained one of the major outstanding problems in atomic collision physics, because of the presence of an open 3d shell in the description of the target ion. Recent theoretical and computational developments and the availability of the national High Performance Computing facilities now enable us to tackle these difficulties.
Atomic data for fusion plasmas
The ITER tokamak, due to begin operation by 2027, represents a culmination of almost a decade of collaborations between countries all around the world. Here at Queen’s, we provide atomic structure and radiative data for many ion stages of tungsten and molybdenum, which are the prime candidates for lining plasma-facing components in these kinds of fusion reactors. One of the main difficulties in the study of these elements is their large atomic weight and complex electronic configurations, but through the continued efforts of our group, we have produced accurate atomic data to aid ongoing experimental work.