Method to estimate the electron temperature and neutral density in a plasma from spectroscopic measurements using argon atom and ion collisional-radiative models

Sciamma, Ella M.; Bengtson, Roger D.; Rowan, W. L.; Keesee, A. M.; Lee, Charles A.; Berisford, Dan; Lee, Kevin M; Gentle, K. W.

doi:10.1063/1.2953577

Cited by 6 publications

(6 citation statements)

References 7 publications

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“…The L λ0 (λ) and S 0 (λ) with wavelength range 400-900 nm are shown in figure 2(b). If the optical field of the view of the lens is smaller than the sphere source aperture, the detected signal S 0 (λ) is independent of the distance between the lens and the light source [25,26]. When the same optical system is used to measure the emission of the plasma, the spectral radiance L λ (λ) at the surface of the plasma can be obtained by…”

Section: Absolute Calibration Of the Optical Systemmentioning

confidence: 99%

Characterization of the hydrogen plasma in the RF negative ion source by optical emission spectroscopy

Yang

et al. 2023

Phys. Scr.

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Optical emission spectroscopy (OES) is an important noninvasive diagnostic tool for providing insight into the plasmas of the negative ion sources. The plasma spectroscopic characterization of the RF driven negative ion source at Huazhong University of Science and Technology (HUST) is studied with the delivered power from 6 kW to 16 kW. The gas temperature, electron temperature, electron density and the density ratio of atomic hydrogen to molecular hydrogen are extracted from OES. The gas temperature is estimated from the Fulcher band of H2. A global thermal model is developed to investigate the gas heating mechanisms in hydrogen plasmas. The gas temperature calculated by the model using the electron density and electron temperature from OES as input parameters is in good agreement with that from the experiment. The thermal model shows that the dissociation of molecular hydrogen by electron impact is the dominant source of gas heating and that approximately 11%~12% of the delivered power is dissipated in gas heating at 0.3 Pa filling pressure. Moreover, the electron temperature, electron density and the ratio of atomic to molecular density are obtained from the absolute intensity of Balmer lines and Fulcher band by using collisional radiative (CR) models of H and H2. The kinetics of the excited states of H are also discussed.

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Section: Absolute Calibration Of the Optical Systemmentioning

confidence: 99%

Characterization of the hydrogen plasma in the RF negative ion source by optical emission spectroscopy

Yang

et al. 2023

Phys. Scr.

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“…The new parameter set [log 10 (n e /n 0 ) , 1/T el , 1/T eh , log 10 R] is denoted as Θ ′ in the following sensitivity analysis, where n 0 is set as 10 10 cm −3 . This value is also selected as a normalization quantity for both 1s and 2p level densities, equations ( 14) and (15). Second, for a given set of emission line intensities, the value of Θ ′ may distribute over a wide range due to the uncertainty of the measurement.…”

Section: Sensitivity Analysis Of Relative Intensities Of 2p-1s Emissi...mentioning

confidence: 99%

“…It has been * Author to whom any correspondence should be addressed. used to study the electron temperature and neutral density [15], and neutral density profile [16] in helicon plasmas. It has also been used to study the EEDF in lowpressure discharges under various gas types or mixtures (e.g.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of determining electron energy distribution function using optical emission lines in low-pressure Ar/Kr discharge

Qiu,

Lei,

2023

Plasma Sources Sci. Technol.

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The electron energy distribution function (EEDF) were reconstructed from both collected emission line intensities and a collisional radiative model. The obtained EEDFs from this method were compared with those obtained from Langmuir probe diagnostics over a wide range of discharge conditions ( n e ∼1010–1012 cm − 3, T eff ∼ 1–3 eV, p gas ≲ 67 Pa) for low-pressure Ar/Kr discharges. In particular, we investigated the factors that affect the accuracy and uncertainty of the EEDF via sensitivity analysis. The following conclusions were obtained: (1) using a sufficiently large number (≳20–30) of Ar/Kr2p-1s emission lines can increase the accuracy of the determined EEDF; (2) for discharges with low electron densities, using emission line sets for both Ar and Kr [instead of only one (Ar or Kr) line set] can significantly reduce the uncertainty in the determined EEDF.

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“…The other end of the open drift tube was connected to a fast ion gauge and as the open tube end was moved across the plasma column, the gas pressure profile was measured [6]. Some groups have used spectroscopic techniques, such as emission line measurements coupled with collisional-radiative (CR) modeling [7] or two-photon laserinduced fluorescence (LIF) [8] to measure inhomogeneities in neutral density profiles arising from radially varying levels of electron-impact ionization and other effects, such as those introduced by magnetic nozzle geometries [9]. Other groups have assumed a uniform neutral pressure profile and employed spectroscopic measurements of the neutral temperature to infer that the neutral density decreases significantly along the axis of cylindrically symmetric low-temperature laboratory plasmas [10].…”

Section: Introductionmentioning

confidence: 99%

Enhanced neutral depletion in a static helium helicon discharge

Houshmandyar

Scime

2012

Plasma Sources Sci. Technol.

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Laser-induced fluorescence (LIF) measurements of plasma opacity are used as a novel diagnostic to determine the absolute density of a metastable state of neutral helium atoms in a helicon plasma. The absorption scale length at a wavelength of 587.725 nm (vacuum) is determined from measurements of fluorescence intensity as a function of distance along the laser path. With a collisional-radiative model of the state populations, the absolute ground state neutral helium density is estimated from the metastable state density measurement. This paper expands upon previous work through measurements of neutral density, temperature and flow at different radial positions. The measured neutral density decreases by two orders of magnitude from the edge of the plasma to the axis of the plasma source. When the helicon source is operated in a static mode (i.e. no active gas pumping) the on-axis neutral density decreases by 69% from the pumping case and the on-axis plasma density increases by 42%; yielding an ionization fraction of approximately 90%.

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Method to estimate the electron temperature and neutral density in a plasma from spectroscopic measurements using argon atom and ion collisional-radiative models

Cited by 6 publications

References 7 publications

Characterization of the hydrogen plasma in the RF negative ion source by optical emission spectroscopy

Characterization of the hydrogen plasma in the RF negative ion source by optical emission spectroscopy

Feasibility of determining electron energy distribution function using optical emission lines in low-pressure Ar/Kr discharge

Enhanced neutral depletion in a static helium helicon discharge

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