The mechanism of striation formation in plasma display panels

Iza, Felipe; Yang, Sung Soo; Kim, H.C.; Lee, Jae Koo

doi:10.1063/1.2007851

Cited by 37 publications

(53 citation statements)

References 17 publications

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“…Strong modulations of the plasma density and light emission -termed as "striations" -have extensively been studied in electropositive DC discharges [19][20][21][22], wherein ion-acoustic or ionization waves form the basics of these features. Striations also occur in electropositive inductively coupled plasmas [23], plasma display panels [24], and in plasma clouds in the ionosphere [25,26]. In these system the appearance of striations is explained by theories based on the electron kinetics.…”

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confidence: 99%

Experimental Observation and Computational Analysis of Striations in Electronegative Capacitively Coupled Radio-Frequency Plasmas

et al. 2016

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Self-organized spatial structures in the light emission from the ion-ion capacitive RF plasma of a strongly electronegative gas (CF4) are observed experimentally for the first time. Their formation is analyzed and understood based on particle-based kinetic simulations. These "striations" are found to be generated by the resonance between the driving radio-frequency and the eigenfrequency of the ion-ion plasma (derived from an analytical model) that establishes a modulation of the electric field, the ion densities, as well as the energy gain and loss processes of electrons in the plasma. The growth of the instability is followed by the numerical simulations.Plasmas in electronegative gases exhibit complex physical and chemical kinetics [1][2][3][4][5][6][7][8][9][10][11]. Their main constituents are typically positive and negative ions, and electrons are only present as a minor species. Such a composition leads to unique effects, e.g., the dominant mechanism of electron energy gain is typically due to the ambipolar and drift electric fields within the ion-ion plasma bulk [12][13][14][15][16][17][18], in sharp contrast with the mechanisms in (more common) electropositive (electron-ion) plasmas where the dynamics of the boundary sheaths conveys energy to the electrons.Being complex dynamical systems, plasmas are susceptible to various instabilities. Strong modulations of the plasma density and light emission -termed as "striations" -have extensively been studied in electropositive DC discharges [19][20][21][22], wherein ion-acoustic or ionization waves form the basics of these features. Striations also occur in electropositive inductively coupled plasmas [23], plasma display panels [24], and in plasma clouds in the ionosphere [25,26]. In these system the appearance of striations is explained by theories based on the electron kinetics. Little is known, however, about the nature of striations in electronegative plasmas where the ion kinetics may play the dominant role: observations have been limited to DC plasmas [27,28], and striations have never been observed in electronegative capacitively-coupled RF (CCRF) plasmas, to our best knowledge. Here we report the observation of striations, that form in the bulk of electronegative CCRF plasmas. The experimental observations are compared with simulation data, which allow a detailed investigation of the underlying physics.In the experiment (described in detail in [18]) the plasma is produced in CF 4 between two parallel electrodes made of stainless steel with a diameter of 10 cm. The gap between the electrodes is L=1.5 cm. The bottom electrode and the chamber walls are grounded. A sinusoidal voltage of a function generator is amplified and applied to the top electrode via a matching network. The generator is also connected to a pulse delay generator that triggers in a synchronized manner an intensified charge-coupled device (ICCD) camera for Phase Resolved Optical Emission Spectroscopy (PROES) measurements. The ICCD camera is equipped with an objective lens and an interfer...

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Experimental Observation and Computational Analysis of Striations in Electronegative Capacitively Coupled Radio-Frequency Plasmas

et al. 2016

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“…The departure from local equilibrium has been recognized for secondary electrons accelerated in the sheaths and is typically accounted for in hybrid models [2,12]. In microdischarges, however, low-energy electrons may not be in local equilibrium either [18]. In fact, lowenergy electrons in the 100 and 75 m discharges can transit the confining ambipolar potential well without significant energy loss; i.e., they are in the nonlocal regime [5].…”

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Electron Kinetics in Radio-Frequency Atmospheric-Pressure Microplasmas

2007

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The kinetic study of three radio-frequency atmospheric-pressure helium microdischarges indicates that the electron energy probability function is far from equilibrium, and three electron groups with three distinct temperatures are identified. The relative population of electrons in different energy regions is strongly time modulated and differs significantly from values recently reported from fluid analyses. It is also shown that a flux of energetic electrons (" > 5 eV) that comprises up to 50% of the total electron flux can reach the electrodes. This energetic electron flux provides a new means of delivering energy to the electrodes and tuning the surface chemistry in atmospheric-pressure discharges. The three electron groups and the engineering of an energetic electron flux might open up a new paradigm in plasma-surface chemistry that has not been considered up until now.

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“…In this paper, a current-driven atmospheric-pressure helium microdischarge is simulated using a 1-D particle-in-cell Monte Carlo collision (PIC-MCC) model. This model can capture fundamental plasma physics that cannot be simulated with fluid models such as nonlocal plasma kinetics, collisionless heating, and striation formation [13]- [16]. The PIC-MCC simulation results are compared, when possible, with the fluid simulation results that are reported in [2].…”

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confidence: 99%