Effects of emitted electron temperature on the plasma sheath

Sheehan, J. P.; Kaganovich, Igor; Wang, H.; Sydorenko, Dmytro; Raitses, Yevgeny; Hershkowitz, N.

doi:10.1063/1.4882260

Cited by 39 publications

(36 citation statements)

References 35 publications

(36 reference statements)

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“…al. 28,29 There is a singularity of Ξ for SD, UD and pMD respectively, which is consistent with the prediction of Sheehan's work for the case of "kinetic solution with loss cone". 33 In general, the singularity of Ξ happens due to the zero current condition (i.e.…”

Section: Resultssupporting

confidence: 78%

“…Secondly, based on the Bohm criterion with account for emitted electrons, 4,28 i.e. lim x→0 + dn i /dφ − dn pe /dφ − dn ee /dφ φ ≥ 0, the ion energy at plasma sheath edge can be…”

Section: A Theoretical Modelmentioning

confidence: 99%

“…27 The effect of emitted electron temperature (EET) on potential of critical SCL sheath was specially investigated in recent several years by Sheehan et.al with kinetic theory analysis, particle-in-cell simulation and experiment measurement. 28,29 They found that EET significantly affects sheath potential, especially sheath potential goes to zero when EET equals T e .…”

Section: Introductionmentioning

confidence: 99%

“…single-velocity distribution (SD), uniform-velocity distribution (UD), half-Maxwellian distribution (hMD) and parabola-like Maxwellian distribution (pMD). The hMD is an accurate assumption for thermionic emission; 28 the SD was used in some former literatures; 6,30 the UD is chosen just for comparison; considering that, for SEE dominated wall boundary, the EEVDF induced by a single-energy incident electron beam presents complex bimodal (i.e. two peaks) configuration, 31,32 we choose pMD (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Effect of total emitted electron velocity distribution function on the plasma sheath near a floating wall

Qing

Zhou

2017

AIP Advances

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Electrons emitted from a solid surface can noticeably affect characteristics of plasma sheath surrounding that surface by modifying current balance at wall, charge separation in sheath region and Bohm criterion at sheath edge. We establish a static sheath model with kinetic electrons and cold ions to emphasize the effect of different total emitted electron velocity distribution functions (EEVDFs) on classic sheath solution and its structure transition. Four total EEVDFs with same average energy are considered separately. It is found that total EEVDFs influence the sheath solution and the threshold of total electron emission coefficient (EEC) for classic sheath dramatically, and can cause no solution for critical space-charge limited (SCL) sheath. These results indicate that, as EEC increases from zero gradually, the sheath will not transit from classic sheath to SCL sheath structure for some special total EEVDFs.

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Section: Resultssupporting

confidence: 78%

Section: A Theoretical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of total emitted electron velocity distribution function on the plasma sheath near a floating wall

Qing

Zhou

2017

AIP Advances

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“…This expression is widely used, in conjunction with the Maxwell's equations (3.9)-(3.12), to describe many plasma behaviours, as the Landau dumping [96] or the noncollisional sheath [97,98]. It is easy to see how, in absence of non-homogeneous terms or boundary conditions, the distribution function evolution is defined by two convective effects, the electromagnetic force and the velocity v.…”

Section: Collisionless Plasma From a Kinetic Point Of Viewmentioning

confidence: 99%

Propagator integral method for plasma physics kinetic equations with practical applications

Muñoz¹

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Heat flow through a plasma sheath in the presence of secondary electron emission from plasma‐wall interaction

Zhao

2017

Contributions to Plasma Physics

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KEYWORDSenergy transmission coefficient, plasma sheath, secondary emission electron, sputtering yield INTRODUCTIONThe characteristics of a plasma sheath located between a plasma and a material surface play an important role in the plasma heat flow to the material surface during plasma-wall interaction. Several key factors influence the sheath structure, including electron emission, [1][2][3][4][5][6][7][8][9][10][11] magnetic field, [11][12][13][14][15] ion temperature, [13][14][15] and collision. [15][16][17] The most important one is the electron emission from plasma-wall interaction. It greatly reduces the sheath potential so that the thermal insulation may become substantially low because the potential drop across the sheath is a potential barrier for the incoming plasma electrons. The emission electron flux through the sheath may be regulated by the space-charge-limited (SCL) effect. The investigation of the plasma sheath in the presence of secondary electron emission (SEE) has been carried out based on several models. [1][2][3][4][5][6] However, many models consider cold ions, whereas the effect of ion temperature has not been studied systematically. For the edge plasma in fusion devices, the ion temperature is comparable to or higher than the electron temperature. [18][19][20][21] In addition, it is shown from sheath model results that the ion temperature influences the sheath properties. [13][14][15] Since the ion temperature in the tokamak edge region is important for the estimation of heat flux flowing to material surface and modelling plasma-wall interaction processes including impurity sputtering, [19] here we describe a plasma sheath with thermal ions in the presence of SEE. When heat flows through the plasma sheath, the sheath energy transmission coefficient , defined as the energy flux normalized by the particle exhaust flux times the electron temperature at the sheath entrance, [22] is used to estimate the energy flux flowing to the target plate in fusion device experiments and to provide boundary conditions in fusion plasma edge fluid codes.increases when SEE is taken into account or as the ion temperature is increased for a given SEE coefficient. [23] Another important physical process affected by the sheath structure is impurity production. Intrinsic impurities (e.g., Be, C, Mo, and W) are produced through erosion during the energy load on the plasma-facing material. The impurity sputtering yield depends

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Effects of emitted electron temperature on the plasma sheath

Cited by 39 publications

References 35 publications

Effect of total emitted electron velocity distribution function on the plasma sheath near a floating wall

Effect of total emitted electron velocity distribution function on the plasma sheath near a floating wall

Propagator integral method for plasma physics kinetic equations with practical applications

Heat flow through a plasma sheath in the presence of secondary electron emission from plasma‐wall interaction

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