Space‐Charge Limited Current from Plasma‐Facing Material Surface

Takamura, S.; Ohno, Noriyasu; Ye, M. Y.; Kuwabara, T.

doi:10.1002/ctpp.200410017

Cited by 132 publications

(146 citation statements)

References 35 publications

Supporting

Mentioning

142

Contrasting

Order By: Relevance

“…In this article, we extend the work presented in Ref. [23] by adding the effect of secondary electron emission by retrodiffusion of primary electrons. The addition of this new ingredient is motivated by the fact that between 10 and 40 percent of primary electrons reaching a tungsten wall could bounce on it [11].…”

Section: Introductionmentioning

confidence: 72%

“…The sheath entrance or plasma limit is at x → −∞. Following the notations of reference [23] (see also Fig. 1 (b)), the sheath region at x < 0 is labeled α (i.e.…”

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

“…We follow the lead of Takamura and co-workers [23] and add to the calculation a new population of electrons: the primary electrons that have rebounded elastically on the material as their contribution could be non-negligible. As a novelty, we also derive a model for the potential of a floating material by establishing numerically the dependence of the virtual cathode potential with the different plasma parameters.…”

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

“…In the space-charge limited regime, only part of the electrons emitted by the wall, those having a sufficiently high velocity to override the virtual cathode potential barrier (Φ vc − Φ w ), reach the α region. The calculation, detailed in the work by Takamura and coworkers [23], is only briefly recalled here. Assuming energy and flux conservation and a Maxwellian distribution function f e (v e ) of emitted electrons at the wall location x = x w , the density of passing emitted electrons reads:…”

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

“…In section II, a model for the space-charge limited emission current regime is derived, following the calculation given in Ref. [23] and adding retrodiffusion of primary electrons. In this section, we also derive an analytical expression of the potential drop between the wall and the virtual cathode potentials.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Strongly emissive plasma-facing material under space-charge limited regime: Application to emissive probes

et al. 2017

View full text Add to dashboard Cite

A quasi-static theoretical 1D model is developed to describe the sheath structure of a strongly emissive plasma-facing material and is subsequently applied to emissive probes' experimental data—which are usually supposed to be an efficient tool to directly measure plasma potential fluctuations. The model is derived following the space-charge limited emission current model developed in Takamura et al., [Contrib. Plasma Phys. 44(1–3), 126–137 (2004)], adding the contribution of secondary emission due to back-diffusion of plasma electrons at the emitting surface. From this theory, current-voltage characteristics of emissive probes are derived. A theoretical relation between the floating potential of an emissive probe and plasma parameters is obtained and a criterion is derived to determine the threshold between the thermoemission limited current regime and space-charge limited current regime. In the space-charge limited regime, a first order expansion is then applied to the quasi-static relation to study the effect of plasma fluctuations on emissive probe measurements. Both the mean values and the fluctuations of the floating potential of an emissive probe predicted by the model, as well as the potential value at which the transition between emission current regimes occurs, are compared to three sets of experimental data obtained in two different plasma devices.

show abstract

Section: Introductionmentioning

confidence: 72%

“…The sheath entrance or plasma limit is at x → −∞. Following the notations of reference [23] (see also Fig. 1 (b)), the sheath region at x < 0 is labeled α (i.e.…”

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

Section: A Hypothesis Of the Model And Outlinementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Strongly emissive plasma-facing material under space-charge limited regime: Application to emissive probes

et al. 2017

View full text Add to dashboard Cite

show abstract

Fluid Model of a Sheath Formed in Front of an Electron Emitting Electrode Immersed in a Plasma with Two Electron Temperatures

Gyergyek

Čerček

2005

Contrib. Plasma Phys.

View full text Add to dashboard Cite

The formation of a sheath in front of a negatively biased electrode (collector) that emits electrons is studied by a one-dimensional fluid model. Electron and ion emission coefficients are introduced in the model. It is assumed that the electrode is immersed in a plasma that contains energetic electrons. The electron velocity distribution function is assumed to be a sum of two Maxwellian distributions with two different temperatures, while the ions and the emitted electrons are assumed to be monoenergetic. The condition for zero electric field at the collector is derived. Using this equation the dependence of electron and ion critical emission coefficients on various parameters -like the ratio between the hot and cool electron density, the ratio between hot and cool electron temperature and the initial velocity of secondary electrons -is calculated for a floating collector. A modification of the Bohm criterion due to the presence of hot and emitted electrons is also given. The transition between space charge limited and temperature limited electron emission for a current-carrying collector is also analyzed. The critical potential, where this transition occurs, is calculated as a function of several parameters like the Richardson emission current, the ratio between the hot and cool electron density, the ratio between hot and cool electron temperature and the initial velocity of secondary electrons.

show abstract

Sheath in Front of a Negatively Biased Collector that Emits Electrons and is Immersed in a Two Electron Temperature Plasma

Gyergyek¹,

Čerček

2005

Contrib. Plasma Phys.

View full text Add to dashboard Cite

An extension of a recently published [GYERGYEK T.,ČERČEK M. Contrib. Plasma Phys., 45, (2005), 89] one dimensional fluid model of the sheath formation in front of a floating electrode (collector) that emits secondary electrons and is immersed in a two-electron temperature nonmagnetized, collisionless plasma is presented. The electron velocity distribution function is assumed to be a two-temperature maxwellian, while the singly charged positive ions and the emitted electrons are assumed to be monoenergetic. It is assumed that the electrons in the pre-sheath potential drop obey the Boltzmann relation, so that a larger fraction of the hot than of the cool electrons can penetrate to the sheath edge. Our model predicts that the collector can in some cases have 3 and in some cases, when the emission of electrons from the collector is critical, even 5 different floating potentials at the same hot to cool electron temperature and density ratios very far away from the collector.

show abstract

Space‐Charge Limited Current from Plasma‐Facing Material Surface

Cited by 132 publications

References 35 publications

Strongly emissive plasma-facing material under space-charge limited regime: Application to emissive probes

Strongly emissive plasma-facing material under space-charge limited regime: Application to emissive probes

Fluid Model of a Sheath Formed in Front of an Electron Emitting Electrode Immersed in a Plasma with Two Electron Temperatures

Sheath in Front of a Negatively Biased Collector that Emits Electrons and is Immersed in a Two Electron Temperature Plasma

Contact Info

Product

Resources

About