Electron-impact excitation rate-coefficients and polarization of subsequent emission for Ar+ ion

Dipti, Dipti; Srivastava, Rajesh

doi:10.1016/j.jqsrt.2016.02.015

“…However, there are only few experimental studies on electron excitation cross sections of ions due to the inherent difficulty to perform such experiments. Thus, accurate theoretical calculations of electron-ion excitation cross sections [3][4][5][6] are needed to fulfill this requirement.…”

Section: Introductionmentioning

confidence: 99%

Electron impact excitation of Ge-like to Cu-like xenon ions in the extreme ultraviolet

Bharti

¹

,

Srivastava

²

2020

J. Phys. B: At. Mol. Opt. Phys.

Self Cite

3

1

0

View full text Add to dashboard Cite

Electron impact excitation of Ge-like (Xe22+) to Cu-like (Xe25+) highly charged xenon ions are studied and dipole allowed fine-structure transitions in the wavelength range 9–25 nm are considered. We use relativistic distorted wave method to calculate the electron excitation cross sections for the different transitions of the four ions in the scattered electron energy range from excitation threshold to 1500 eV. The ionic bound state wavefunctions have been obtained using multi-configuration Dirac–Fock method. To ascertain the accuracy of the wavefunctions, the wavelengths and oscillator strengths of the considered transitions in these ions are calculated and compared with the previously reported measurements and other theoretical calculations, where available. For plasma diagnostic applications, the obtained cross sections are further used to calculate the rate coefficients of the transitions as well as fitted with an analytical expression which can be used in plasma model conveniently.

show abstract

“…The collisional-radiative (CR) model of Ar has been built and applied to research plasmas under various conditions [28]. Electron-induced processes are anticipated to be the most dominant ones occurring in the plasma in typical low-pressure Ar discharges, with a pressure range of 0.1-30 Pa and n e ranging from 10 9 to 10 13 cm 3 [29]. The process of producing Ar + ion spectral lines is as follows:…”

Section: Argon Kinetic Modelmentioning

confidence: 99%

“…h is the Planck constant (6.63 × 10 −34 J s) and c is the speed of light (3 × 10 8 m s −1 ). Q g→j is the rate coefficient of electron impact excitation from the ground state to excited levels, which is calculated as: Electron impact excitation rate coefficients (in m 3 s −1 ) from the ground state 3p 5 (J = 3/2) to the upper level of Ar ion lines passing through two narrowband filters [37]. Κ value Here E e is the electron kinetic energy, m e is the electron mass (9.11 × 10 −31 kg), g p is the electron energy probability function assuming the electrons to have a Maxwellian distribution [36] and σ(E e ) is the cross section of the relevant electron impact process.…”

Section: Argon Kinetic Modelmentioning

confidence: 99%

“…Κ value Here E e is the electron kinetic energy, m e is the electron mass (9.11 × 10 −31 kg), g p is the electron energy probability function assuming the electrons to have a Maxwellian distribution [36] and σ(E e ) is the cross section of the relevant electron impact process. The cross section data for the transitions from the ground state 3p 5 (J = 3/2) to fine-structure levels of some excited states in Ar+ ions are obtained from [37] and calculated by fully relativistic distorted wave theory. g p and σ(E e ) are functions of T e .…”

Section: Argon Kinetic Modelmentioning

confidence: 99%

See 1 more Smart Citation

High-spatial-resolution image reconstruction-based method for measuring electron temperature and density of the very near field of an applied-field magnetoplasmadynamic thruster

Han¹,

Zhang²,

Chen³

et al. 2021

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

A method based on image reconstruction is proposed for measuring the electron temperature ( T e ) and density ( n e ) distribution of the axisymmetric low-temperature argon plasma plume of applied-field magnetoplasmadynamic thrusters (AF-MPDTs). The method uses a complementary metal–oxide–semiconductor camera with narrowband filters of 460 and 500 nm to obtain the raw projection images in specific wavelength ranges. An image reconstruction method is developed to construct relative emission intensity profiles. The electron temperature distribution can be obtained by combining the relative emission intensity ratio of two profiles with a simple argon kinetic model. The electron density distribution can be calculated by constructing a function of relative emission intensity containing T e and n e . To verify the feasibility of this method, we diagnosed a very near field plume of a 15 kW AF-MPDT and obtained the distribution of parameters with a spatial resolution of 0.23 mm. The results show that the maximum T e and n e are located on the centerline near the exit plane of the thruster and decrease with both radial and axial distances. The second peak appears in the radial direction of both the T e and n e distributions, while their zones do not overlap. A comparative analysis of measurement results obtained by this method and the Langmuir probe method is performed to prove its accuracy. Moreover, this measurement method has the advantages of high spatial resolution and the ability to diagnose high-density and magnetized plasma. This method can be also applied to other optically thin axisymmetric low-temperature argon plasmas.

show abstract

“…While database providing cross sections for neutral lines are widely available 40 the dataset for ArII lines at low electron temperature are very seldom in the literature. The set of cross sections σ ex for the Ar + → Ar + * excitation process was extracted from recent simulations 41 and are shown in Fig. 8a), dashed line.…”

Section: Time Averaged Light Intensity Strongly Depends On T Ementioning

confidence: 99%

High-speed imaging of magnetized plasmas: when electron temperature matters

Vincent,

Dolique,

Plihon

2021

Preprint

0

View full text Add to dashboard Cite

High speed camera imaging is a powerful tool to probe the spatiotemporal features of unsteady processes in plasmas, usually assuming light fluctuations to be a proxy for the plasma density fluctuations. In this article, we systematically compare high speed camera imaging with simultaneous measurements of the plasma parameters -plasma density, electron temperature, floating potential -in a modestly magnetized Argon plasma column at low pressure (1 mTorr, magnetic fields ranging from 160 to 640 G). The light emission was filtered around 488 ± 5 nm, 750 ± 5 nm, 810 ± 5 nm. We show that the light intensity cannot be interpreted as a proxy for the plasma density and that the electron temperature cannot be ignored when interpreting high speed imaging, both for the time-averaged profiles and for the fluctuations. The features of plasma parameter fluctuations are investigated, with a focus on ion acoustic waves (at frequency around 70 kHz) at low magnetic field and low-frequency azimuthal waves (around a few kHz) at larger magnetic fields. An excellent match is found between the high speed images fluctuations and an Arrhenius law functional form which incorporates fluctuations of the plasma density and of the electron temperature. These results explain the discrepancies between ion saturation current and narrow-band imaging measurements previously reported in the literature.

show abstract

Electron-impact excitation rate-coefficients and polarization of subsequent emission for Ar+ ion

Cited by 20 publications

References 41 publications

Electron impact excitation of Ge-like to Cu-like xenon ions in the extreme ultraviolet

Electron impact excitation of Ge-like to Cu-like xenon ions in the extreme ultraviolet

High-spatial-resolution image reconstruction-based method for measuring electron temperature and density of the very near field of an applied-field magnetoplasmadynamic thruster

High-speed imaging of magnetized plasmas: when electron temperature matters

Contact Info

Product

Resources

About