Virtual Instrument for automatic low temperature plasmas diagnostic considering finite positive ion temperature

Díaz‐Cabrera, Juan Manuel; Palop, J. I. Fernández; Crespo, R. Morales; Hernández, M. A.; Tejero-del-Caz, Antonio; Ballesteros, J.

doi:10.1016/j.measurement.2014.04.029

Cited by 12 publications

(76 citation statements)

References 27 publications

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“…The transition takes place only for helium plasmas. Similar experiments on argon and neon plasmas [1,2,[19][20][21][22][23][24] show that the radial theory developed by the authors that takes into account the temperature of the ions, but does not take into account the mass of the ions or the ion mean free path, is successful in predicting the positive ion current.…”

Section: Introductionmentioning

confidence: 78%

“…In low-pressure, low-temperature plasmas, the study of the positive ion current collected by the Langmuir probe is very important, as the smallness of the positive ion current collected by the Langmuir probe when it is polarized negatively with respect to the plasma potential allows local diagnosis of the plasma parameters with very low disturbance to the plasma. In other words, the positive ion sheath that is formed around the probe shields out the influence of the probe, which in plasmas with low plasma density is crucial [1][2][3][4][5][6][7]. On the other hand, many surface technological processes that use plasmas depend on the ion current that reaches the surface, and thus the control of the ion current is essential in this kind of technology.…”

Section: Introductionmentioning

confidence: 99%

“…The Allen-Boyd-Reynolds theory, which was soon adapted to cylindrical Langmuir probes by Chen [18], is valid for ions that have an ion temperature that is negligible when compared to the electron temperature, so that the parameter β = T + /T e , with T + and T e as the positive ion and electron temperature, respectively, can be given a value of β = 0. The cylindrical radial model has been extended by the authors to β 0 [1,2,[19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

“…When the values of the plasma parameters deduced from these theories are compared to the values of the plasma parameters obtained using the much higher electron current in the electron saturation zone, depending on the plasma conditions, it is found that either the radial or the orbital theories are consistent with the well-established electron saturation zone theory. This implies a paradox when the ion current is used in plasma diagnosis, given that the appropriate theory that should be used is not known a priori before it is used in plasma diagnosis [1,4,25]. Actually, in many situations which depend on the plasma discharge power and the pressure, values for the ion current collected by the probe between the two theories are measured in experiments [5,[26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…In radial models, this loss of moment is similar to a friction force in the fluid, so that the positive ion current is reduced. In the orbital models, the ions may lose their orbital velocity, so that, after the last collision, the ions will lose their angular momentum and fall radially towards the probe [1,2,5,7,17,18,26,28], increasing the positive ion current collected by the probe. The effect of collisions is opposed in both models and will affect not only surface technology but plasma diagnosis methods, both depending on the positive ion current.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Influence of the Ion Mass in the Radial to Orbital Transition in Weakly Collisional Low-Pressure Plasmas Using Cylindrical Langmuir Probes

et al. 2020

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This paper presents an experimentally observed transition from the validity of the radial theories to the validity of the orbital theories that model the ion current collected by a cylindrical Langmuir probe immersed in low-pressure, low-temperature helium plasma when it is negatively biased with respect to the plasma potential, as a function of the positive ion-neutral collision mean free path to the Debye length ratio Λ=λ+/λD. The study has been also conducted on argon and neon plasmas, which allows a comparison based on the mass of the ions, although no transition has been observed for these gases. As the radial or orbital behavior of the ions is essential to establish the validity of the different sheath theories, a theoretical analysis of such a transition not only as a function of the parameters Λ and β=T+/Te, T+ and Te being the positive ion and electron temperature, respectively, but also as a function of the ion mass is provided. This study allows us to recognize the importance of the mass of the ion as the parameter that explains the transition in helium plasmas. Motivated by these theoretical arguments, a novel set of measurements has been performed to study the relationship between the Λ and β parameters in the transition that demonstrate that the effect of the ion mean free path cannot be completely ignored and also that its influence on the ion current collected by the probe is less important than the effect of the ion temperature.

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Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Influence of the Ion Mass in the Radial to Orbital Transition in Weakly Collisional Low-Pressure Plasmas Using Cylindrical Langmuir Probes

et al. 2020

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Accurate measurement of the ion saturation current collected by a cylindrical Langmuir probe in cold plasmas

Díaz‐Cabrera

Palop

Regodón

et al. 2020

Plasma Processes & Polymers

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This paper analyzes the results of accurate measurements of the ion current collected by a cylindrical Langmuir probe immersed in cold argon, neon, and helium plasmas. These measurements make it possible to study the influence of the positive ion-to-electron temperature ratio β = T + /T e on the collected ion current, providing valuable information about the trajectory described by the positive ions when falling toward the probe. Several criteria have been applied to discriminate whether the ion current is described by using the orbital motion limited theory or the radial motion theory. In all the studied argon and neon plasma discharge conditions, the criteria indicate that the positive ion current collected by the probe is appropriately described by the radial motion theory; however, as β increases, some criteria indicate a trend toward the orbital theory. In contrast, for the studied helium plasmas discharge conditions, a transition from radial to orbital motion has been measured.

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Ion injection in electrostatic particle-in-cell simulations of the ion sheath

Tejero-del-Caz

Palop

Díaz‐Cabrera

et al. 2017

Journal of Computational Physics

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Virtual Instrument for automatic low temperature plasmas diagnostic considering finite positive ion temperature

Cited by 12 publications

References 27 publications

Influence of the Ion Mass in the Radial to Orbital Transition in Weakly Collisional Low-Pressure Plasmas Using Cylindrical Langmuir Probes

Influence of the Ion Mass in the Radial to Orbital Transition in Weakly Collisional Low-Pressure Plasmas Using Cylindrical Langmuir Probes

Accurate measurement of the ion saturation current collected by a cylindrical Langmuir probe in cold plasmas

Ion injection in electrostatic particle-in-cell simulations of the ion sheath

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