Charged-particles measurements in low-pressure iodine plasmas used for electric propulsion

Esteves, Benjamin; Marmuse, Florian; Drag, Cyril; Bourdon, Anne; Laguna, Alejandro Alvarez; Chabert, Pascal

doi:10.1088/1361-6595/ac8288

Cited by 9 publications

(14 citation statements)

References 40 publications

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“…As an application of these basic measurements on atomic iodine, either in a photodissociation cell or in a plasma, atomic iodine ground state densities and gas temperatures are on the way to be measured in iodine-fed thrusters, i.e. in plasmas between 0.1 and 4 Pa (Esteves et al 2022). That pressure range makes TALIF appear as a quite suitable technique for such diagnostics, as it has been shown in the present work to provide a detection scheme sensitive enough at pressures around 1 Pa.…”

Section: Discussionmentioning

confidence: 99%

“…In a molecular plasma, the electrical energy supplied to the electrons is used to ionize the molecules, but this energy is also dissipated in electronic, vibrational and rotational heating of the molecules. In addition, the transport phenomena are also different in molecular gases, and the relaxation length of the electron energy is expected to be shorter in iodine than in noble gases (Esteves et al 2022). A significant fraction of negative ions is also expected given the very high effective cross section for dissociative attachment (Ambalampitiya et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…A LIF scheme has been studied on I + (Steinberger and Scime 2018) and measurements of the ratio between I + and I + 2 were performed using a mass spectrometer, at the output of a radio frequency ion thruster (Dietz et al 2019). The behavior of electrons was studied by Langmuir probe and laser photodetachment was used to probe negative ions in a low-pressure inductively-coupled plasma chamber used as the ionization stage of a gridded ion-engine (Esteves et al 2022).…”

Section: Introductionmentioning

confidence: 99%

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Two-photon absorption laser induced fluorescence (TALIF) detection of atomic iodine in low-temperature plasmas and a revision of the energy levels of I I

Esteves¹,

Blondel²,

Chabert³

et al. 2023

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

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In order to perfect the use of iodine, instead of xenon, in plasma thrusters, an experiment has been set up to investigate the feasibility of two-photon absorption laser induced ﬂuorescence (TALIF) diagnostics in iodine plasmas. Levels (3P2)6p 2[1]o3⁄2 and (3P2)6p 2[3]o7⁄2 of atomic iodine were found qualiﬁed for that purpose, with a radiative lifetime of the former found equal to 35.5(9) ns, which appears consistent with the 32.5(1.2) ns predicted by the most recent calculations. Doppler-free two-photon spectroscopy has confirmed that the relative intensities of the hyperfine components follow well-known general formulas, which makes it possible to disentangle the hyperfine structure of 127I from Doppler broadening. Accurate temperature measurements are shown to be possible, even though the relatively heavy mass of the iodine atom does not make it the most favorable gauge for measurements based on Doppler e ect. Using an injection seeded pulsed laser as the primary laser source, the frequency-tripling of which has provided the ca 300 nm radiation used for excitation, absolute energy measurements of the two-photon excited levels revealed that all upper energy levels of I I have to be revised down, by -0.169(11)cm-1, which pulls every energy level off its presently tabulated value by more than thirty times the currently admitted uncertainty bar.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two-photon absorption laser induced fluorescence (TALIF) detection of atomic iodine in low-temperature plasmas and a revision of the energy levels of I I

Esteves¹,

Blondel²,

Chabert³

et al. 2023

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

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“…While the measured electron temperature was in fairly good agreement with model predictions, the electron density differed by an order of magnitude. A very recent paper [28] using an iodine model also based on the reaction set from reference [25] has obtained better agreement with some experimental measurements, such as the electron density and electronegativity. An order of magnitude discrepancy in the electron density was also found in reference [29] where a more sophisticated 2D plasma-fluid model was developed, and in addition, almost complete dissociation of molecular iodine was observed with the density of I + 2 ions being about 30× lower than the density of I + ions.…”

Section: Introductionmentioning

confidence: 87%

Development and validation of an iodine plasma model for gridded ion thrusters

Lafleur

Habl

Rossi

et al. 2022

Plasma Sources Sci. Technol.

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Iodine is emerging as an attractive alternative propellant to xenon for several electric propulsion technologies due to its significantly lower cost and its ability to be stored unpressurized as a solid. Because of the more complex reaction processes and energy-loss channels in iodine plasmas however, as well as the historical lack of reliable collision cross-section data, the development of accurate theoretical and numerical models has been hindered. Using recently calculated theoretical cross-sections, we present an iodine plasma model and perform a comparison with experimental data obtained from an iodine-fuelled gridded ion thruster. The model is in reasonable agreement with experimental measurements of the ion beam current, propellant mass utilization efficiency, and ion beam composition, and is able to quantitatively and qualitatively reproduce system behaviour as the input mass flow rate and RF power are varied. In addition, both the model and experiment show that the use of iodine can lead to a performance enhancement when compared with xenon. This occurs because of the combination of different iodine reaction processes, collision cross-section values, and inelastic energy thresholds which result in lower collisional energy losses, as well as an increased antenna-plasma power transfer efficiency for thrusters using a radio-frequency inductive coil.

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“…We study the order of magnitude of the transport fluxes of equations ( 16) and ( 17), and the transport effects of table 1. We use the Langmuir probe measurements in the ICP discharge described in [34,35]. In figure 1, we present the measurements at p g = 5 mTorr and RF power 200 W. In the same figure, we present a fit of the EEDF that uses the Grad's 9M non-equilibrium distribution function.…”

Section: Order Of Magnitude Of the Transport Fluxes In An Icp Dischargementioning

confidence: 99%

Discussion on the transport processes in electrons with non-Maxwellian energy distribution function in partially-ionized plasmas

Laguna

Esteves

Raimbault

et al. 2023

Plasma Phys. Control. Fusion

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In a previous work, we have developed a non-linear moment model for electrons that self-consistently captures non-Maxwellian electron energy distribution function (EEDF) effects. The model does not rely in the local approximation and the transport coefficients are calculated by expanding the distribution function into Hermite polynomials and by taking moments of the Boltzmann equation, including the collision operator for elastic and inelastic collisions with arbitrary cross sections. This model captures the classical Fick's, Fourier's, and Ohm's law as well as Soret, Dufour, and Peltier effects. In addition, novel non-local transport phenomena appear as a result of spatial gradients of the kurtosis of the distribution function. In this paper, we discuss on the transport effects by analyzing two collisional models: constant collision frequency and constant cross section. We estimate the order of magnitude of the transport processes in non-equilibrium electrons by analyzing the Langmuir probe measurements of a low-pressure argon inductively-coupled discharge. The results show that, under these conditions, the transport produced by the spatial gradients in the kurtosis of the distribution function produces a heat-flux contribution that is of the same order of magnitude as the Fourier and Dufour's effects. These transport effects are beyond the local field or the electron gradient expansions, commonly used in the low-temperature plasma modelling.

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Charged-particles measurements in low-pressure iodine plasmas used for electric propulsion

Cited by 9 publications

References 40 publications

Two-photon absorption laser induced fluorescence (TALIF) detection of atomic iodine in low-temperature plasmas and a revision of the energy levels of I I

Two-photon absorption laser induced fluorescence (TALIF) detection of atomic iodine in low-temperature plasmas and a revision of the energy levels of I I

Development and validation of an iodine plasma model for gridded ion thrusters

Discussion on the transport processes in electrons with non-Maxwellian energy distribution function in partially-ionized plasmas

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