The recovery of glow-plasma structure in atmospheric radio frequency microplasmas at very small gaps

In atmospheric radio frequency discharges at 13.56 MHz, with the electrode gap reduced, the sheath region eventually occupies a main portion of the electrode spacing and the bulk plasma region is significantly compressed. The computational results in this letter based on a one-dimensional fluid model show that by increasing the excitation frequency over 13.56 MHz, the traditional glow-plasma structure could gradually recover even at very small sizes with a well defined quasineutral plasma region, and the electron density is improved but the electric fields in sheath region are reduced. This study indicates that the excitation frequency can be used to modulate the discharge structure and then tailor the plasma-surface interaction in atmospheric microplasmas.

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