Generation of Microplasma Using Pulsed Discharge of Ethanol Droplet in Air

Abstract

An ethanol droplet of 300 mm in diameter is used to create a dense microplasma by pulsed discharge. The pulsed discharge took place when the droplet came into the space between miniature electrodes across which a dc high voltage was applied. The vaporization and dissociation of the ethanol droplet were confirmed in the discharge because the atomic line of hydrogen was observed by optical emission spectroscopy. Molecular hydrogen was detected as a product after the discharge of the ethanol droplet. The discharge of a droplet in air and that of a micro bubble in liquid are in opposite configurations, which is a duality in nature. A single microbubble discharge in pure water was conducted. The gas breakdown of air took place in the bubble and bright emission was observed locally at the interface between the bubble and the electrode.

Atmospheric DC Glow Microplasmas Using Miniature Gas Flow and Electrolyte Cathode

“…We reported the microplasma created by pulsed discharges of an ethanol droplet or a filament formed at the tip of Taylor cone as the initial materials. 1,2) These schemes were effective for reactions at the interface between a plasma and a liquid because a typical size of plasma was on the order of 50 -1000 mm. The microplasmas, however, are usually operated in the pulsed mode and have difficulty in continuous operation, owing to complicated processes for preparing droplets or liquid filaments.…”

Universal Cone Angle of ac Electrosprays Due to Net Charge Entrainment

“…The positive-mode spectrum of ac electrospray showed only background noise without any discernable cation, in contrast to distinct peaks in positive-mode mass spectra of ethanol using dc electrospray ionization [9]. The dissociation time scale of ethanol at the kV range is known to be about 100 ns [10], which is less than the half cycle of the applied field at about 50 ms. The mobilities of the proton and the ethoxide ion differ by an order of magnitude [11], which allows the entrainment of ethoxide ions at the tip.…”

Formation of Ethanol Filament and Its Pulsed Discharge for Microplasma Generation

“…As long as a spatially isolated small structure is obtainable, any state of matter such as gas, 2) liquid, 3) or solid 4) is applicable for the method. In the case of liquid, one can use a droplet or a filament as the initial material.…”

“…Because the density of liquid is higher than that of gases, it is expected that dense microplasmas will be generated easily. While we reported previously the use of an ethanol droplet as the initial material, 3) physical analysis on the development of droplet discharges is complicated because it has a threedimensional structure. On the other hand, there is no report on the use of liquid filaments to create microplasmas.…”