The LisbOn KInetics Boltzmann solver

Abstract

The LisbOn KInetics Boltzmann (LoKI-B) is an open-source simulation tool (https://github. com/IST-Lisbon/LoKI) that solves a time and space independent form of the two-term electron Boltzmann equation, for non-magnetised non-equilibrium low-temperature plasmas excited by DC/HF electric fields from different gases or gas mixtures. LoKI-B was developed as a response to the need of having an electron Boltzmann solver easily addressing the simulation of the electron kinetics in any complex gas mixture (of atomic/molecular species), describing first and second-kind electron collisions with any target state (electronic, vibrational and rotational), characterized by any user-prescribed population. LoKI-B includes electron-electron collisions, it handles rotational collisions adopting either a discrete formulation or a more convenient continuous approximation, and it accounts for variations in the number of electrons due to nonconservative events by assuming growth models for the electron density. On input, LoKI-B defines the operating work conditions, the distribution of populations for the electronic, vibrational and rotational levels of the atomic/molecular gases considered, and the relevant sets of electron-scattering cross sections obtained from the open-access website LXCat (http://lxcat. net/). On output, it yields the isotropic and the anisotropic parts of the electron distribution function (the former usually termed the electron energy distribution function), the electron swarm parameters, and the electron power absorbed from the electric field and transferred to the different collisional channels. LoKI-B is developed with flexible and upgradable object-oriented programming under MATLAB ® , to benefit from its matrix-based architecture, adopting an ontology that privileges the separation between tool and data. This topical review presents LoKI-B and gives examples of results obtained for different model and real gases, verifying the tool against analytical solutions, benchmarking it against numerical calculations, and validating the output by comparison with available measurements of swarm parameters.

Data Needs for Modeling Low-Temperature Non-Equilibrium Plasmas: The LXCat Project, History, Perspectives and a Tutorial

“…This problem is often circumvented by the inclusion of such information in the form of contributor-specific annotations in the comment blocks. As an example, the Lisbon database for N 2 [101] contains comments specifying detailed state information that is used by the LoKI-B Boltzmann solver [187]. This observation suggests the possibility of improving on the original format by the inclusion of optional lines such as "S: 0."…”

“…Moreover, this approach hampers code reuse both internally and externally. One can envision plasma modeling tools such as BOLSIG+ [27], LoKI-B [187], HPEM [224] and PLASIMO [225], providing integrated access to data sets on LXCat with a suitable abstraction. Such implementation would of course have to abide to the LXCat policy on data redistribution with the written consent required on a case-by-case basis between the contributors and the third parties (see Appendix B).…”

“…growth models for the electron density to describe non-conservative events. LoKI-B can easily simulate the electron kinetics in any complex gas mixture (of atomic/molecular species), describing first and second-kind electron collisions with any target state (electronic, vibrational and rotational), characterized by any user-prescribed population [187]. • THERMCAT: A fast and robust online tool for simulation of different modes of axially symmetric current transfer from high-pressure arc-discharge plasmas to cylindrical thermionic cathodes, created and maintained by Mikhail Benilov and co-workers.…”

Plasma Modeling and Prebiotic Chemistry: A Review of the State-of-the-Art and Perspectives

“…Several codes are available as open-source for calculation of the Electron Velocity Distribution Function (EVDF). Most of them are based on the two-term expansion of the EVDF in Legendre polynomials, such as BOLSIG+ [ 64 ] and LoKI-B [ 80 ]. At the expenses of computational time, other codes employ different numerical methods based on multi-term expansion of the EVDF in Legendre polynomials (e.g., the MultiBolt code [ 81 ]) and Monte Carlo (MC) simulations (e.g., the METHES code [ 82 ]), in order to obtain more accurate calculations.…”

Plasma-enhanced catalysis for the upgrading of methane: a review of modelling and simulation methods

“…Nonetheless, nowadays solvers embedded within commercial software (e.g. COMSOL and PLASIMO) or distributed as freeware (BOLSIG+, 89 EEDF, 90 and LoKI 91 ) are available and are used routinely by the research community, 28,37,92 so that the assumption of an ideal theoretical distribution, such as that of Maxwell or Druyvesteyn, is no longer required. Figure 1 compares the Maxwell and Druyvesteyn electron energy distribution functions for a pure methane plasma with those obtained using different freely available Boltzmann equation solvers at a mean electron energy of 5 eV.…”