Investigations on the stability of the low pressure positive column in oxygen
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Physics D: Applied Physics |
| MU Faculty or unit | |
| Citation | |
| Web | http://dx.doi.org/10.1088/0022-3727/42/14/145207 |
| Field | Plasma physics |
| Keywords | instability;glow discharge;positive column;oxygen;waves |
| Description | The stability of low pressure positive column in oxygen was investigated. The studied H- to T-mode transition showed a marked hysteresis in the E(I) characteristics which is affected by wall processes. At small discharge current the el. field showed a significant modulation, characterized by incoherent fluctuations with a broadband Fourier spectrum. With increasing current the discharge operates in the T-mode, where a mode selection with high modulation degree occurred, resulting in a periodic oscillation of the electric field at a discrete frequency spectrum. The dynamic state in the T-mode is expressed by T-waves moving from the cathode to the anode. The stability was studied using a hydrodynamic model considering electrons, positive and negative ions as well as metastable O2 molecules. In good agreement with the experiments the transition was explained as a linear unstable equilibrium state where the energy dependence of the corresponding rate coefficients is the driving mechanism. |
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