Time-resolved avalanche current waveforms in octafluorocyclobutane

Avalanche currents have been measured by means of a time-resolved swarm method in c-C₄F₈ at pressures between 0.7 and 27 kPa. The recorded avalanche current waveforms are, in comparison with those of most insulating gases, unusual. Whereas, in most gases, avalanche current waveforms are characterized by a clear distinction between the electron contribution (high amplitude, short duration) and the ion contribution (low amplitude, long duration), the waveform in c-C ₄F₈ is significantly different. During the first electron transit time an electron component can only be observed at low pressure (below 1.3 kPa) and even then is strongly intermixed with the ion contribution. Above ~1.3 kPa the waveform seems completely ion-dominated