The LisbOn KInetics (LoKI) Suite

The LisbOn KInetics (LoKI) Suite requires quality data to deliver useful predictions on the behaviour of low-temperature plasmas. Thus, the development of tools is accompanied by the consolidation of state-of-the-art kinetic schemes for various gases and gaseous mixtures.

The procedure involves:
(i) the critical assessment of data (electron scattering cross sections and heavy-species rate coefficients);
(ii) the validation of kinetic schemes, by comparing simulation results with experimental measurements (mainly obtained by optical and mass spectroscopy diagnostics) for the intensities of the main radiative line/band transitions and/or the densities of the main excited species in the plasma;
(iii) the public release of electron scattering cross sections for momentum-transfer, excitation to electronic / vibrational / rotational states, attachment and ionization, through the IST-Lisbon database on the open-access website LXCat (currently in the process of migration to the new LXCat 3.0 and the LXCat (future) databases);
(iv) the distribution / publication of the kinetic schemes and data as KInetic Testbeds (KITs) (to be hosted in the new ChemCat database).

The LoKI-Suite tools and data leverage the expertise in the field of non-equilibrium low-temperature plasmas accumulated over many years by the Portuguese group N-Plasmas Reactive: Modelling and Engineering (N-PRiME).

The current efforts focus on argon, helium, nitrogen, oxygen, hydrogen, carbon monoxide, carbon dioxide, ammonia, tetrafluoromethane, and related mixtures, delivering kinetics schemes for these systems (see graphs below).

Presently, LoKI-Suite gives open-acess to the following kinetic schemes, available at LoKI-GM/Code/Input

• Oxygen, published at
  T. C. Dias, C. Fromentin, L. L. Alves, A. T. del Caz, T. Silva and V. Guerra
  A reaction mechanism for oxygen plasmas
  Plasma Sources Sci. Technol. 32 084003 (2023)
• Carbon dioxide (no vibrations), based on the chemistry published at
  A. F. Silva, A. S. Morillo-Candás, A. Tejero-del-Caz, L. L. Alves, O. Guaitella and V. Guerra
  A reaction mechanism for vibrationally-cold low-pressure CO₂ plasmas
  Plasma Sources Sci. Technol. 29 125020 (2020)
• Nitrogen (no vibrations), based on the chemistry published at
• V. Guerra, A. Tejero-del-Caz, C. D. Pintassilgo and L. L. Alves
  Modelling N₂–O₂ plasmas: volume and surface kinetics
  Plasma Sources Science and Technology 28 073001 (2019)
• M. Jiménez-Redondo, A. Chatain, O. Guaitella, G. Cernogora, N. Carrasco, L. L. Alves and L. Marques
  N₂–H₂ capacitively coupled radio-frequency discharges at low pressure. II: Modelling results: the relevance of plasma-surface interaction
  Plasma Sources Science and Technology 29 085023 (2020)

These studies include also identifying consistent cross section sets for electron collisions with the following atoms/molecules:

• Ar (collisions with ground-state Ar(¹S₀); swarm validated);
• He (collisions with ground-state He(¹S₀); swarm validated);
• N2 (collisions with ground-state N₂(X) and N₂(X,v=0); swarm validated), N2-vib (with N₂(X,v=1-10)), N2-rot (with N₂(X,v=0,J=0-30) ΔJ=2).
  The latter two datagroups are clustered under Nitrogen at LXCat;
• N (collisions with ground-state N(⁴S)), N-elec (with N(²D) and N(²P)).
  These datagroups are clustered under Nitrogen at LXCat;
• O2 (collisions with ground-state O₂(X) and O₂(X,v=0); swarm validated), O2-vib (with O₂(X,v=0-41)), O2-rot (with O₂(X,v=0,J=1-29) ΔJ=2), O2-elec (with excited electronic states, namely O₂(a¹Δ_g, b¹Σ⁺_g)).
  The latter three datagroups are clustered under Oxygen;
• O (collisions with ground-state O(³P)), O-elec (with excited electronic states, namely O^-).
  These datagroups are clustered under Oxygen;
• O3 (collisions with ground-state O₃(X)).
  This datagroup is clustered under Oxygen;
• H2 (collisions with ground-state H₂(X) and H₂(X,v=0); swarm validated), H2-vib (with H₂(X,v=1-15)), H2-rot (with H₂(X,v=0,J=0-5) ΔJ=2), H2-elec (for electron recombination of H₂⁺ and H₃⁺).
  The latter three datagroups are clustered under Hydrogen;
• H (collisions with ground-state H(1s)), H-elec (with H(2s), H(2p), H(3), H(4) and H(5)).
  These datagroups are clustered under Hydrogen;
• CO2 (collisions with ground-state CO₂(X) and CO₂(X,v=000); swarm validated);
• CO (collisions with ground-state CO(X) and CO(X,v=0); swarm validated), CO-rot (with CO(X,v=0,J=0-17) ΔJ=1);
• CO_anis (collisions with ground-state CO(X) and CO(X,v=0) to be adopted when anisotropic scattering for rotational collisions is also considered; swarm validated), CO_dipint-rot (dipole-integral cross sections for rotational excitation with CO(X,v=0,J=0-25) ΔJ=1), CO_dipmt-rot (dipole-momentum-transfer cross sections for rotational excitation with CO(X,v=0,J=0-25) ΔJ=1), CO_quadint-rot (quadrupole-integral cross sections for rotational excitation with CO(X,v=0,J=0-24) ΔJ=2).
  These datagroups are clustered under CO_anis.
• NH3: (collisions with ground-state NH₃(X); swarm validated), NH3-rot (with NH₃(X,v=0,J=0) ΔJ=1-5).
  These datagroups are published in the new LXCat (future) database.