James Colgan is a theoretical atomic physicist at Los Alamos National Laboratory who works generally on atomic processes in plasmas, and a member of the Editorial Board of JPhysB. He has recently been involved in generating new opacities for use in astrophysical modeling, and modeling low-temperature plasmas. He also studies fundamental atomic & molecular collision processes such as the three-body Coulomb problem found in many few-particle scattering processes.
Q: Which research projects are you and your group currently working on?
Our main research interest is in studying atomic processes in plasmas – that is, understanding how the atomic physics processes such as excitation, ionization, and recombination modify and change plasma properties. Such processes often determine the plasma temperatures and densities. Our modeling is based on the ability to construct and compute datasets of atomic structure and collision cross sections, which are often needed for wide ranges of atoms and atomic ions. The range and quality of the atomic data is of course very important in plasma modeling, and much effort is placed into extending and improving atomic structure and collision codes to continuously improve our modeling capabilities. More recently I have become more involved in modeling lower temperature plasmas, which places greater emphasis on the atomic data from neutral atoms and near-neutral ions, and may also require knowledge of molecular scattering quantities.
Q: What motivated you to pursue this field of research?
Knowledge of atomic and molecular interactions really underpins many other areas of physics, especially astrophysics and plasma physics. The links and overlaps with condensed matter physics and chemistry are also becoming stronger in my view. The study of atomic and molecular processes is attractive because of this exposure to diverse areas of physics. However, some effort is involved in understanding what (atomic physics) quantities are really needed to contribute to other physics research areas. While the field of atomic structure and collision physics has sometimes suffered in the past from having been seen as “mature”, it still remains an indispensable area of physics that is of fundamental importance. I have always appreciated this central role played by this field, and I think it has the potential to lead to many new and sometimes unexpected opportunities.
Q: Where do you think the field is heading?
I think the atomic structure & collision field will make important strides in the future in modeling complex atoms, which are currently poorly understood. I am thinking especially of complex targets such as the transition metals, and the fearsome lanthanides and actinides, which have notoriously very complex atomic structure properties.
Q: What current problem facing humanity would you like science to provide a solution to?
Climate change – I am a little hopeful that a game-changing technological advance could help significantly mitigate the warming trend we are experiencing. This is vitally important to the future of humanity and especially the most vulnerable populations.
Q: Who inspired you to become a scientist?
Two things: excellent high school mathematics and physics teachers at Loreto College, Coleraine, Northern Ireland, and a book I read sometime in high school called “The Quantum Universe” which uncovered some of the bizarreness and excitement of quantum physics.
Q: What has been the most exciting development in physics during the course of your career?
The discovery of the existence of dark matter and dark energy. This makes us realize that most of the “stuff” in the Universe is completely unknown to us. How exciting is that?!
On behalf of JPhysB I would like to thank Professor Colgan for talking to us and for all his work on JPhysB’s Editorial Board. You can read some of his recent work in the journal here:
- Five-photon double ionization of helium
- Two-photon triple ionization of Li
- Observation of two-center interference effects for electron impact ionization of N2
This work is licensed under a Creative Commons Attribution 3.0 Unported License
Front image and image 1: copyright James Colgan; used with permission.
Image 2: TDCC calculations of the two-photon triple ionization cross section of Li at a photon energy of 115 eV, for various fixed electron angles and for equal energy sharing between the ejected electrons. The thick red lines are the total cross sections and the green and orange lines represent the contributions from the 2S and 2D contributions, respectively. The polarization direction epsilon is indicated by the green line, from J Colgan and M S Pindzola 2015 J. Phys. B: At. Mol. Opt. Phys. 48 181001, Image Ⓒ IOP Publishing, Reproduced with permission. All rights reserved.