The transition from an ionizing electron collecting plasma sheath into an anodic double layer as a bifurcation
The electron attracting plasma sheath adjacent to the surfaces of a positively polarized electrode transforms into an anodic double layer over a threshold bias potential. The proposed one-dimensional model for this transition considers the contribution of the low production of charges by electron im...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_1070664X_v13_n11_p_Conde |
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| Sumario: | The electron attracting plasma sheath adjacent to the surfaces of a positively polarized electrode transforms into an anodic double layer over a threshold bias potential. The proposed one-dimensional model for this transition considers the contribution of the low production of charges by electron impact in the sheath, which develops a positive space charge in front of the electrode. The stationary electric field of this ionizing plasma sheath as well as the plasma potential spatial profile are obtained from the numerical solutions of a nonlinear integral equation derived from the Poisson equation. The stationary transition process is governed by a bifurcation driven by the bias potential of the electrode, which is the parameter controlled in the experiments. Below a bias potential threshold a single and stable ionizing plasma sheath is obtained. Past this critical voltage two possible values are found for the electric field close to the surface of the electrode. The double layer space plasma profile corresponds to low electric fields while a ionizing plasma sheath is found for higher values. It is conjectured that the abrupt transition occurs when the plasma sheath becomes unstable for bias voltage over a threshold and the double layer develops. The discontinuities in the current voltage characteristic curves observed in the experiments as the double layer upsurges or disappears would be explained as jumps between the two possible branches of this bifurcation. © 2006 American Institute of Physics. |
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