Electrical Breakdown Study in CO₂ and CO₂-O₂ Mixtures in AC, DC and Pulsed Electric Fields at 0.1–1 MPa Pressure

Abstract

In this paper, the results of AC, DC and 2/160 µS impulse electrical breakdown experiments of CO 2 and CO 2-O 2 mixtures in weak and strongly non-uniform fields are presented. In weakly non-uniform fields, the electrical breakdown field approximately follows 11 when stressed with both AC and DC (positive and negative) waveforms. For positive impulse, the breakdown voltage is higher and the time lag to breakdown is scattered, indicating a lack of starting electrons from CO 2 gas. The breakdown strengths of CO 2-O 2 (10-30%) mixtures is investigated. On application of negative polarity impulse, the breakdown strength is significantly higher than positive impulse in the measured pressure range of 0.3-0.7 MPa in strongly non-uniform fields, contrary to that seen during breakdown in weakly non-uniform fields. Breakdown voltage for negative impulse is further enhanced in a mixture of CO 2-O 2 (80-20%).

The Nanosecond Impulsive Breakdown Characteristics of Air, N2 and CO2 in a Sub-mm Gap

“…When such a thermalized plasma channel is formed, the current rises sharply and the voltage across the gap collapses. It was found that in the present experimental conditions, the thermalisation time (i.e., the time interval between the first significant current spike and the moment of the sharp rise in current) is almost the same, ~ (11)(12) ns, for all tested gases and gas pressures, which indicates that this time is governed by the parameters of the pulsed power circuit used in these tests. Therefore, U br-ch is the voltage at which the initial breakdown plasma channel is formed in the gas-filled gap; the main streamer starts to develop through this channel, leading to its thermalisation.…”

“…The numerical values of the fitting parameters, C and D, obtained in OriginPro graphing software for each gas are given in Table 2. 11 shows Nt as a function of E/N for air, N2 and CO2 and includes: the results obtained in the present work (Ntbr as a function of Etip/N), the kinetic model results (Ntf as a function of E/N), and the results previously published in the literature, [10,11,[22][23][24], and [34][35][36][37]. Each experimental point shown in Figure 11 represents the average value obtained using 20 individual data points, the error bars show the 95% confidence interval values, (some original experimental points do not appear to have error bars as a result of these bars being too small to display relative to the size of the point).…”

“…(c) Etip/N as a function of Nd in CO2. Experimental data, present work: ○-negative polarity; •-positive polarity; experimental data [11]: △-negative polarity; ▲-positive polarity; solid line, fitting curve Equation ( 6).…”

“…The literature data are based on both formative and (in some cases) total time to breakdown and were obtained under various experimental conditions (type of electrodes, inter-electrode distances, gas pressures, high-voltage pulse characteristics). Details of each specific set of experimental conditions can be found in [10,11,[22][23][24][34][35][36][37]. -positive polarity (monocone) [24]; - [23]; solid line, fitting curve, Equation ( 6).…”

“…In [10], for example, the breakdown and recovery characteristics of a spark-gap filled with nitrogen were investigated, with a view to facilitating the development of compact, low-inductance spark gap switches for pulsed power applications. In [11], the breakdown properties of CO 2 and CO 2 -O 2 mixtures were investigated under different energization regimes, for prospective power industry applications (for example gas-filled circuit breakers); and in [12], the breakdown properties of air stressed with ns impulses have been studied to provide further quantitative information on the plasma kinetics of air. Other advanced applications that require detailed information on the breakdown of gases in short gaps include plasma-assisted ignition and combustion [13,14]; plasma thrusters for miniature flying robots [15]; environmental and medical applications [16,17]; and the fabrication of nanomaterials [18].…”