Electric field breakdown at micrometre separations in air and nitrogen at atmospheric pressure

Abstract

For efficient operation, micromotors and microactuators, such as those employed in microsystems, are required to operate with high electric fields at electrode separations of the order of micrometres. An apparatus was built to accurately measure the breakdown voltage for electrode spacings as low as 0. 5~. Breakdown voltage measurements in air and nitrogen are presented and discussed for the gap range 0.5 to 1 5~. Energy dispersive analysis of X-rays (EDAX) confirms the transfer of material from cathode to anode and vice V L ' I :~ during the breakdown mechanism. The Paschen law has been confirmed not to be applicable at gap settings of less than 4 p. The shape of the curve and the breakdown voltage values are found to be the same for different gases and different high pressures up to 4 p separation. Below this value, an analytical explanation of the breakdown voltage based on quantum tunnelling of electrons is obtained in terms of electrical field enhancement at microprotrusions and the work function of the electrode material.

20 years of microplasma research: a status report

“…The smallest gaps for which the breakdown voltage in atmospheric-pressure gas (air and N 2 ) was measured were approximately half a micrometer [26,27]. Since the electrical breakdown voltage in such small gaps is strongly affected by the surface roughness of the electrodes [28], reproducible electric field breakdown results for these extremely small gaps could only be obtained by polishing the electrodes to a very high finish [26,27].…”

“…Since the electrical breakdown voltage in such small gaps is strongly affected by the surface roughness of the electrodes [28], reproducible electric field breakdown results for these extremely small gaps could only be obtained by polishing the electrodes to a very high finish [26,27].…”

Electrical breakdown at low pressure for planar microelectromechanical systems with <inline-formula><math display="inline" overflow="scroll"><mrow><mn>10</mn><mtext>-</mtext><mspace width="0.3em" /><mtext>to</mtext><mspace width="0.3em" /><mn>500</mn><mtext>-</mtext><mi>μ</mi><mi mathvariant="normal">m</mi></mrow></math></inline-formula> gaps

“…With the exception of the work of one group, 12,14,15 Paschen curves for micron-scale gaps have been measured at atmospheric pressure, 1,4,16,17 typically in air, which is reasonable given that this is the normal operating condition for MEMS devices. Although Baars-Hibbe et al 11 report on measurements down to 10 kPa, their main objective was creating atmospheric plasmas.…”

“…The limitation of the Paschen curve at micron-scale gaps at atmospheric pressure has become clear in the past few years. [1][2][3][4][5][6] The importance of the role of field emission and vapor arc have been demonstrated for gaps smaller than 10 m, leading to the description of the "modified" Paschen curve. 4 The general conclusion has been that a maximum safe voltage is 300 V for gaps 4 m or larger at a pressure of one atmosphere, and that the breakdown voltage decreases rapidly for smaller gaps due to field emission.…”

Micromachined chip-scale plasma light source

“…The Paschen curve [8] provides a good starting point for estimating the DC voltage required to ignite a plasma. Significant deviations from the Paschen curve are reported for gaps smaller than 5 m due to field emission [9][10][11][12][13][14]. At larger gaps deviations are also reported, in particular for RF operation because of the additional length scales brought into play for RF operation [17].…”