scholarly journals Development of a Plasma Chemistry Model for Helicon Plasma Thruster analysis

2021 ◽  
Author(s):  
Enrico Majorana ◽  
Nabil Souhair ◽  
Fabrizio Ponti ◽  
Mirko Magarotto
Keyword(s):  
Cross Sections ◽  
Inductively Coupled Plasma ◽  
Plasma Chemistry ◽  
Velocity Distribution Function ◽  
Rate Coefficients ◽  
Helicon Plasma ◽  
Plasma Thruster ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Helicon Discharges

AbstractThe present work is part of a wider project aimed at improving the description of the plasma dynamics during the production phase of a Helicon Plasma Thruster. In particular, the work was focused on the development of a chemical model for Argon- and Xenon-based plasma. The developed model consists of a collisional radiative model suitable to describe the dynamics of the 1s and 2p excited levels. The model is meant to be complementary to 3D-VIRTUS, a numerical tool which enforces a fluid description of plasma, developed by the University of Padova to analyse helicon discharges. Once identified, the significant reactions for both propellants, the reaction rate coefficients, have been integrated exploiting cross sections from literature and assuming a Maxwellian velocity distribution function for all the species. These coefficients have been validated against experimental measurements of an Argon Inductively Coupled Plasma and compared with a well-established code. For Argon, the selected reactions have been reduced through a proposed lumping methodology. In this way, it was possible to reduce the number of equations of the system to solve, and implement them into 3D-VIRTUS. A validation against an experimental case taken from literature was performed, showing good agreement of the results. Regarding the Xenon model, only a verification has been performed against the results of another collisional-radiative model in literature. Finally, a predictive analysis of the propulsive performances of a Helicon Plasma Thruster for both Argon and Xenon is presented.

scholarly journals Investigation of a Collisional Radiative Model for Laser-Produced Plasmas

Atoms ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 52
Author(s):  
Nicholas L. Wong ◽  
Fergal O’Reilly ◽  
Emma Sokell
Keyword(s):  
Radiative Recombination ◽  
Rate Coefficients ◽  
Ion Distribution ◽  
Ion Distributions ◽  
Nist Database ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Collisional Ionization ◽  
Three Body ◽  
Body Recombination

Plasmas of a variety of types can be described by the collisional radiative (CR) model developed by Colombant and Tonan. From the CR model, the ion distribution of a plasma at a given electron temperature and density can be found. This information is useful for further simulations, and due to this, the employment of a suitable CR model is important. Specifically, ionization bottlenecks, where there are enhanced populations of certain charge states, can be seen in these ion distributions, which in some applications are important in maintaining large amounts of a specific ion. The present work was done by implementing an accepted CR model, proposed by Colombant and Tonon, in Python and investigating the effects of variations in the ionization energy and outermost electron subshell occupancy term on the positions of ionization bottlenecks. Laser Produced Plasmas created using a Nd:YAG laser with an electron density of ∼ne = 1021 cm−3 were the focus of this work. Plots of the collisional ionization, radiative recombination, and three-body recombination rate coefficients as well as the ion distribution and peak fractional ion population for various elements were examined. From these results, it is evident that using ionization energies from the NIST database and removing the orbital occupancy term in the CR model produced results with ionization bottlenecks in expected locations.

scholarly journals Intensities in Complex Spectra of Highly Ionized Atoms

1984 ◽  
Vol 86 ◽  
pp. 44-44
Author(s):  
M. Klapisch ◽  
A. Bar-Shalom ◽  
A. Cohen
Keyword(s):  
Cross Sections ◽  
Wave Functions ◽  
Coupling Scheme ◽  
Distorted Wave ◽  
Intermediate Coupling ◽  
Potential Wave ◽  
Excitation Cross Sections ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Efficient Program

We describe a package of programs for the implementation of the collisional-radiative model to complex configurations. The number of levels taken into account may be several hundreds. The heart of the package is a very efficient program for excitation cross sections in the Distorted Wave framework, using the Relativistic Parametric Potential wave functions. The basic jj coupling scheme actually simplified the computations, enabling a useful factorization into radial and angular parts. Intermediate coupling and configuration interactions are accounted for. We computed ratios of intensities of 3d9 − 3d84s (E2) to 3d9 −3d84p (El) transitions as functions of ne and Te in Xe XXVIII and other Co-like spectra. The atomic model involves all the levels of configurations (3p6)3d9; −3d84s, −3d84p, −3d84d, −3d84f, and (3p5) −3d10, −3d94p. (275 levels) and all the transitions between them. Results compare very well with experimental spectra from TFR.

Accurate calculations of cross sections and rate coefficients of some atom - diatom reactions relevant to plasma chemistry

1997 ◽  
Vol 6 (3) ◽  
pp. 270-279 ◽  
Author(s):  
A Laganà ◽  
S Crocchianti ◽  
G Ochoa de Aspuru ◽  
A Riganelli ◽  
E García
Keyword(s):  
Cross Sections ◽  
Plasma Chemistry ◽  
Rate Coefficients

Non L.T.E. Properties of Quasistationary Oxygen Plasmas

1976 ◽  
Vol 31 (3-4) ◽  
pp. 362-368 ◽  
Author(s):  
M. Cacciatore ◽  
M. Capitelli
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Ground State ◽  
Radiative Recombination ◽  
Local Thermodynamic Equilibrium ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Ionization Coefficients ◽  
Selection Of ◽  
The Continuum

The non L.T.E. (local thermodynamic equilibrium) properties of optically thin and thick quasistationary oxygen plasmas have been calculated for the temperature range k T = 0.5 - 1.5 eV and for the electron density interval 108 - 1016 cm-3 , by using the collisional-radiative model of Bates, Kingston and McWhirther. The results include1 the coefficients r0(i) and r1(i), which represent the contribution to the population density of the ith quantum level from the continuum and from the ground state, respectively2 the values of α and S, which are the collisional-radiative recombination and ionization coefficients, respectively. The accuracy of the present results is discussed in connection with the adopted plasma model and with the selection of the collisional cross sections for forbidden and allowed transitions. A discussion is also presented of the influence of the two low lying excited states of oxygen atoms (i.e. the states 2p41D, 2p41S) on the non L.T.E. properties of these plasmas. A satisfactory agreement is found with the calculations of Julienne et al. and with the experimental results of Jones.

scholarly journals Spectroscopy in Ne-Like Plasmas. Z-Dependence of the Atomic Data Used in a Collisional-Radiative Model

1988 ◽  
Vol 102 ◽  
pp. 95-97
Author(s):  
M. Cornille ◽  
J. Dubau ◽  
M. Loulergue ◽  
S. Jacquemot
Keyword(s):  
Radiative Decay ◽  
Dielectronic Recombination ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Structure Scheme ◽  
Distorted Waves ◽  
Laser Experiments

AbstractThe Livermore X-ray Laser experiments in 1984 have shown the existence of Ne-like 3p-3s population inversions in a collisional Se plasma (Z=34) with significant gains (5 cm-1). We have focused our efforts on the behavior of the gains along the target neon Isoelectronic sequence. This study implies the determination of the Z-dependance of the rate coefficients of all the Involved atomic processes: collisional excitation (C). radiative decay (A) and dielectronic recombination (αd). Thus we use atomic structure and electron-ion collisional codes (SUPERSTRUCTURE. Distorted Waves. AUTOLSJ and JJOM). The different calculations have been done on a large selection of ions, from Ar to Ag. They Include relatlvistic effects in a fine structure scheme. The Z-dependance of the numerical results is expressed as polynomial or rational forms.

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