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Simulation software for strongly coupled plasma


TECHNOLOGY AREAS: Information Systems, Materials/Processes

OBJECTIVE:  Develop algorithms and tools to advance the state-of-the-art in the simulation of plasma in the strongly coupled limit, where the energy associated with the long range coulomb fields is larger than the thermal energy associated with the particles.

DESCRIPTION:  Strongly coupled plasmas occur in a wide range of physical situations from ultra-cold neutral plasmas and tenuous ionosphere plasmas[1] through explosive gases associated with conventional munitions to the extreme conditions associated with high-energy ultrafast laser interactions with matter, even touching on warm dense matter physics[3]. Since the flow of energy in these situations is both critical to the functioning of Air Force technology, and central to our fundamental understanding of plasma physics, it is important to have theory and related software to understand and predict plasma behavior in the strongly coupled regime.  Non-equilibrium plasmas are playing an important role in a variety of Air Force high technology products, either by virtue of providing the background operating environment (for space-based assets), the means by which electrical energy is converted into high power electromagnetic signals (directed energy sources), novel plasma chemistry (in micro-plasma devices), or fundamental limits for certain classes of quantum information systems (trapped ion and cold atom systems). The creation and evolution these non-equilibrium plasmas and the management of energy flow in these potentially high energy density situations is important to the further research and development of a wide range of Air Force technology. Currently, methods based on particle-in-cell (PIC) tools and single-fluid (MHD) models are the workhorse enabling computational technology to design and evaluate the intersections between plasma scenarios and Air Force needs.

While the PIC and MHD software packages have reached a relatively high state of development, with robust numerical algorithms, scalable parallel implementations, and high-fidelity physical accuracy, these codes generally simulate so-called "classical" plasmas [2] where the kinetic energy of the charged particle population greatly exceeds the potential energy associated with Coulomb self-fields. Note that this is in contrast to other uses of the term "classical" in the context of quantum mechanical processes in plasmas.  When the Coulomb field energy becomes large, however, traditional methods of plasma physics often fail, as the inter-particle dynamics and multi-particle correlations become important. The physics associated with this development often require fine resolution of the spatial dynamics that involves length scales significantly shorter than the screening Debye length associated with classical plasmas. These small spatial scales naturally introduces novel time scales and equilibration processes that are important to understand and simulate. This involves coupling multiple physical phenomena for retaining the long-range forces common in plasmas with the short-range inter-particle forces more commonly associated with molecular dynamics. Finally, although this lies outside the scope of the current topic, this is clearly important physics toward the eventual inclusion of quantum processes in plasma physics.

PHASE I:  Based on novel concepts beyond the current state-of-the-art, develop a plan to build and validate a strongly coupled plasma simulation model. Plan should address modeling, development of algorithms, implementation of computer code and, given the wide range of plasma parameters exhibiting strongly coupled phenomena, first tests of results for one physical system.

PHASE II:  Develop algorithms for a strongly coupled plasma simulation tool and implement in prototype computer code appropriate for, at least, two-dimensional physical scenarios. Again, given the wide rate of potential physical arenas, apply code to simulate two specific systems, and test simulation results against observed data from the literature.


Military Application:  Use the tool to characterize the impact of strongly coupled plasma in high-power electromagnetic fields for counter-directed energy, explosive blast situations, and space-weather effects on electronics.

Commercial Application:  The tool will also have broad application to novel chemistry based on micro-plasma technology for novel environmental remediation, and for quantum information systems based on trapped ions for secure business transactions.

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