Equation for thermionic emission in a plasma

Ostretsov, I. N.; Petrosov, V. A.; Porotnikov, A. A.; Rodnevich, B. B.

doi:10.1007/bf00850418

Cited by 3 publications

(5 citation statements)

References 3 publications

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“…20) In addition, thermionic emission provides abundant electrons, which results in dense plasma formation. 21) Therefore, collision frequencies increase among electrons, ions, and atoms, and a high gas temperature is expected to be achieved.…”

Section: Pw Apparatus With 3 MM Channel Diametermentioning

confidence: 99%

Generation of stationary high-density cascade arc plasma and application to plasma windows

Yamasaki

Yanagi

Sunada

et al. 2023

Jpn. J. Appl. Phys.

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We have developed indirectly heated hollow cathode electrodes and a cascade arc discharge apparatus with different channel diameters to realize plasma windows (PWs) as virtual vacuum interfaces. A compact arc discharge source with a channel diameter of 3 mm is fabricated to realize windowless vacuum–atmosphere separation. An atmospheric high-density Ar thermal plasma is generated, and a PW that produces 100 kPa and 81 Pa separation is demonstrated. An 8 mm channel diameter arc device is also constructed for application as an alternative differential pump with the separation of low- and high-pressure vacuum chambers, and the production of a high-density He plasma. Pressure differences of 2.5 kPa and 16 Pa between PWs are realized. Moreover, vacuum ultraviolet and visible emission spectroscopy reveal the characteristics of expanding plasmas and the plasma parameters.

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Section: Pw Apparatus With 3 MM Channel Diametermentioning

confidence: 99%

Generation of stationary high-density cascade arc plasma and application to plasma windows

Yamasaki

Yanagi

Sunada

et al. 2023

Jpn. J. Appl. Phys.

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“…Note that when considering a floating object immersed in the plasma, the equilibrium condition is reached when the electric field in the sheath ensures a net current equal to zero; in summary, the equilibrium is reached at a sheath potential equal to V f , such that:

which implies:

Applying a potential to the wall negative with respect to the plasma potential, and different from V f , leads to a net current flowing in the sheath. In this case, an I-V model for a plane electrode with area A biased with a voltage

based on an equivalent junction [ 31 , 32 ], can be derived by writing the total transport current in the sheath,

, exploiting Equations (A7) and (A8):

where we can observe that the current described by Equation (A11) consists of two terms, the leftmost one that can be modeled by an equivalent constant current generator,

, and the rightmost term, which can be represented by an equivalent diode contributing with a current

, hence:

The current

was derived considering a constant ion velocity over the sheath. On the other hand, the accelerating effect of the electric field on ions can be modelled by exploiting the energy conservation in the sheath:

where

, and where

and

are the ion velocity and the potential at

, respectively.…”

Section: Figure A1mentioning

confidence: 99%

“…Applying a potential to the wall negative with respect to the plasma potential, and different from V f , leads to a net current flowing in the sheath. In this case, an I-V model for a plane electrode with area A biased with a voltage

based on an equivalent junction [ 31 , 32 ], can be derived by writing the total transport current in the sheath,

, exploiting Equations (A7) and (A8):

where we can observe that the current described by Equation (A11) consists of two terms, the leftmost one that can be modeled by an equivalent constant current generator,

, and the rightmost term, which can be represented by an equivalent diode contributing with a current

, hence:

…”

Section: Figure A1mentioning

confidence: 99%

Ion Current Sensor for Gas Turbine Condition Dynamical Monitoring: Modeling and Characterization

Addabbo

Fort

Landi

et al. 2021

Sensors

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This paper aims to thoroughly investigate the potential of ion current measurements in the context of combustion process monitoring in gas turbines. The study is targeted at characterizing the dynamic behavior of a typical ion-current measurement system based on a spark-plug. Starting from the preliminary study published in a previous work, the authors propose a refined model of the electrode (spark plug), based on the Langmuir probe theory, that incorporates the physical surface effects and proposes an optimized design of the conditioning electronics, which exploits a low frequency AC square wave biasing of the electrodes and allows for compensating some relevant parasitic effects. The authors present experimental results obtained in the laboratory, which allow for the evaluation of the validity of the model and the interpreting of the characteristics of the measurement signal. Finally, measurements carried out in the field on an industrial combustor are presented. The results confirm that the charged chemical species density sensed by the proposed measurement system and related to the mean value of the output signal is an indicator of the ‘average’ combustion process conditions in terms e.g., of air/fuel ratio, whereas the high frequency spectral component of the measured signal can give information related to the turbulent regime and to the presence of pressure pulsations. Results obtained with a prototype system demonstrated an achievable resolution of about 5 Pa on the estimated amplitude, even under small biasing voltage (22.5 V) and an estimated bandwidth of 10 kHz.

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“…5) Nous supposons que tous les ions atteignant la cathode sont neutralisés sur celle-ci et ne rebondissent pas. Ceci nous conduit d'après I. N. Ostretsov et al [6] à des valeurs du champ électrique trop élevées, mais d'après ces auteurs la correction est faible et devient négligeable pour des champs électriques de l'ordre de ceux que nous avons obtenus, vu notre précision expérimentale. 6) Pour le bilan de puissance, nous supposons que les échanges d'énergie au niveau de la tache cathodique ont lieu instantanément en comparaison du temps d'arc, même lorsque celui-ci se réduit à 10-3 s.…”

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“…m-2. Ceci nous conduit à des pressions partielles pour les vapeurs métalliques de l'ordre de 10' Pascal ce qui justifie l'utilisation de la relation (6).…”

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Étude des grandeurs caractéristiques de la tache cathodique d'un arc électrique

Andanson

Bouculat

Cheminat

et al. 1977

Rev. Phys. Appl. (Paris)

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Abstract. 2014 The cathode of an electric arc burning freely in air was studied during a halfwave of a sinusoidal, 50 Hz current. For mean intensities ranging from 500 to 2 000 A, five characteristic parameters for the cathode spot were determined : the mean radius a, the temperature T, the electric field E, the total current density J, and the fraction s of the current density due to electrons. The experimental measurement of the erosion of the cathode together with five simultaneous equations enabled the parameters above to be obtained for copper and silver electrodes. The first part of the results gives mean values. The second part shows the changes occuring in the cathode spot as a function of time for the half-wave of the current.

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Equation for thermionic emission in a plasma

Cited by 3 publications

References 3 publications

Generation of stationary high-density cascade arc plasma and application to plasma windows

Generation of stationary high-density cascade arc plasma and application to plasma windows

Ion Current Sensor for Gas Turbine Condition Dynamical Monitoring: Modeling and Characterization

Étude des grandeurs caractéristiques de la tache cathodique d'un arc électrique

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