Experimental and Theoretical Investigations of Anode Double Layer

Gurlui, Silviu; Agop, M.; Strat, M.; Strat, Georgeta; Bācāiţā, Simona

doi:10.1143/jjap.44.3253

Cited by 11 publications

(12 citation statements)

References 20 publications

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“…This has been verified by using the Helium gas also, for which the potential difference is measured to be ∼ 24 V . It has been reported numerous times that in case of the formation of fireball at the anode the potential difference between the anode and plasma is always close to the ionization potential of the gas used in the discharge 8,10,11,22 . The visual observation of the anode beyond 25 Gauss of applied magnetic field confirms the presence of localized bright anode spot or fireball.…”

Section: Plasma Potential and Floating Potentialmentioning

confidence: 99%

Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge

et al. 2018

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The electron sheath formation in a DC magnetised plasma of modified hollow cathode source is studied. The discharge consists of two plane parallel cathodes and a small cubical anode placed off axis at the center. The argon plasma is produced and the properties of the plasma in response to the sheath formation near the anode are studied using electrical and optical diagnostics. In particular, the effect of pressure, magnetic field on discharge parameters such as discharge current, plasma potential, plasma density and electron temperature is studied. The discharge showed an onset of anode glow at a critical applied magnetic field indicating the formation of electron sheath and a double layer. The discharge current initially decreases; however it starts to rise again as the anode spot appears on the anode. The critical magnetic field at which anode glow formation takes place is dependent upon operating pressure and discharge voltage. The transition from ion sheath to electron sheath is investigated in detail by Langmuir probe and spectroscopy diagnostics. The plasma potential near the anode decreases during the transition from ion sheath to electron sheath. The plasma potential locks to the ionization potential of argon gas when anode spot is completely formed. A systematic study showed that during the transition, the electron temperature increases and plasma density decreases in the bulk plasma. The spectroscopy of the discharge showed presence of strong atomic and ionic lines of argon. The intensity of these spectral lines showed a dip during the transition between two sheaths. After the formation of the anode spot, oscillations of the order of 5-20 kHz are observed in the discharge current and floating potential due to the enhanced ionisation and excitation processes in the electron sheath. The reason of the electron sheath formation at particular magnetic field is attributed to the reduction of the electron flux reaching to the anode in the direction perpendicular to the magnetic field.

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Section: Plasma Potential and Floating Potentialmentioning

confidence: 99%

Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge

et al. 2018

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“…The transition from electron sheath to anode glow has been observed experimentally [6] and was numerically investigated by Conde et al [7]. Anode spots have been observed to have a spherical shape, first called 'fireballs' by Song et al [8], and subsequently by others [9][10][11][12][13][14][15], or a cylindrical shape, first called 'firerods' by An et al [16], and subsequently by others [17,18]. Multiple fireballs have also been observed either as nested concentric spheres, 'multiple concentric double layers,' [19][20][21][22][23][24][25][26], or at multiple distinct locations on the anode surface, 'non concentric multiple double layers' [20,21,23,27,28].…”

Section: Introductionmentioning

confidence: 96%

Equilibrium states of anodic double layers

Baalrud

Longmier

Hershkowitz

2009

Plasma Sources Sci. Technol.

116

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Equilibrium states of anodic double layers that form near a positively biased disk-shaped electrode immersed in a partially ionized plasma are studied experimentally using electrostatic probes. When the potential drop from the electrode to the plasma is less than a critical value, φ c , an anode glow is observed where a double layer potential drop is within a few millimeters of the electrode surface. For larger biases an anode spot forms where the double layer potential drop is centimeters from the electrode and the intervening region is a plasma more luminous than the bulk plasma. A theoretical model is developed which predicts that φ c ∝ 1/P + C, where P is the neutral pressure and C is a constant, and it predicts hysteresis in the current-voltage characteristic at the electrode; both effects are observed experimentally. The model also provides an estimate for the distance between the electrode and double layer potential drop that agrees with the measurements. Near small electrodes, anode spots are observed to be 'fireballs,' which are spherical in shape. Near larger electrodes 'firerods' are found instead, which have a cylindrical shape. It is shown that firerods are required by global current balance because they have a smaller effective electron collecting area than fireballs. Experiments also confirm that global nonambipolar flow (Baalrud S D et al 2007 Phys. Plasmas 14 042109) accompanies firerods. In this case all electrons are lost through the firerod to the electrode, while all positive ions are lost to the other plasma boundaries.

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“…This is the most dangerous effect of chemical contamination, affecting the active section of the tubular components, which can reach a critical section, leading to catastrophic consequences in the operation of a jet engine. We note that a similar effect occurs in the controlled release of drugs by diffusion complex at low temperatures (critical, subcritical and supercritical) [10][11][12][13] and plasma discharge [14][15][16].…”

Section: Discussionmentioning

confidence: 83%

Intergranular degradation of stainless steel tubular components used for kerosene transportation. Metallographic analysis

et al. 2017

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Abstract. The chemical interactions between the kerosene compounds and the stainless steel structure of the tubular components, through which kerosene is transported, develop a degradation phenomenon, causing intergranular contamination from the surface to the inner part (process based also on mass transport, i.e. diffusion at low temperatures). This is the most dangerous effect of chemical contamination, affecting the active section of the tubular components, which can reach a critical section, leading to catastrophic consequences in the operation of a jet engine. Metallographic analysis of the tubular components of such a jet engine, manufactured from stainless steel 12H18N10T, through which kerosene has been transported, come to confirm the intergranular contamination.

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Experimental and Theoretical Investigations of Anode Double Layer

Cited by 11 publications

References 20 publications

Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge

Electron sheath evolution controlled by a magnetic field in modified hollow cathode glow discharge

Equilibrium states of anodic double layers

Intergranular degradation of stainless steel tubular components used for kerosene transportation. Metallographic analysis

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