Waveforms of Prebreakdown Primary Streamers in a Short Positive Point-Plane Gap in Air

Inoshima, Masayuki; Černák, Mirko; Hosokawa, Tatsuzo

doi:10.1143/jjap.29.1165

Cited by 9 publications

(6 citation statements)

References 13 publications

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“…The proposal of a common mechanism for both the streamer/cathode interaction in a short positive point-plane gap and the Trichel pulse is corroborated also by similar results for CO2 presented in an Accessory Publication. * Following this line of reasoning, the recent experiments of Inoshima et al (1990), using CuI coating in a short positive point-plane gap, show that the coating has no perceptible effect on the waveforms of the pulses generated during the neutralisation of the primary streamers at the cathode. This is in apparent correspondence with the modest effect on the Trichel pulse waveforms in Figs 18, 19 and 20 and emphasises further the analogy between the simple-shaped Trichel pulses and the current pulses generated during the streamer neutralisation on the cathode.…”

Section: (B) Concept Of Cathode-directed Streamer Associated With Trichel Pulse Risementioning

confidence: 89%

Negative Corona Current Pulses and Cathode Sheath Instabilities in a Short Point-Plane Gap in CO2

Černák¹,

Hosokawa²

1992

Aust. J. Phys.

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Waveforms ofthe first negative corona current pulses have been measured in C02 and C02+SF6 mixtures as a function of applied voltage and gas pressure in the range 6�67-66�7 kPa. A complex form of the pulses with a step on the pulse leading edge and a current hump on the pulse trailing part has been found at gas pressures below 40 kPa. Changing the cathode surface material from copper to copper iodide, which has an exceptionally high photoelectric yield, resulted in at least a twofold increase in height of the step on the pulse leading edge, but had little effect on the main current rise to the pulse peak. The use of unconditioned cathodes resulted in the appearance of peculiar current spikes on the pulse tail, which are tentatively attributed to positive-streamer-like instabilities of the cathode sheath. The implications of these results for theories of Trichel pulse formation are discussed, and a physical picture of the phenomenon based on the presumed existence of a cathode-directed streamer associated with the steep pulse rise is outlined.

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Section: (B) Concept Of Cathode-directed Streamer Associated With Trichel Pulse Risementioning

confidence: 89%

Negative Corona Current Pulses and Cathode Sheath Instabilities in a Short Point-Plane Gap in CO2

Černák¹,

Hosokawa²

1992

Aust. J. Phys.

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“…The light reflection from the cathode surface, together with the small size and short duration of the cathode spots have made it too difficult to obtain their time-and spaceresolved optical measurements. Fortunately, one of the advantages of short (∼1 cm) positive point-plane air gaps is that, using proper pulsed voltage and optimized electrode geometry, it is possible to minimize the generation of a multistreamer bunch and the streamer branching [35,[146][147][148] like those seen in figures 5 and 6. This, as reported by Larsson [149], see figure 7, enables to measure the discharge current corresponding to the single streamer propagation in a virgin air and its arrival to the cathode with a nanosecond temporal resolution:…”

Section: Streamer Phenomena In Non-uniform Fieldsmentioning

confidence: 99%

Streamer breakdown: cathode spot formation, Trichel pulses and cathode-sheath instabilities

Černák

Hoder

Bonaventura

2020

Plasma Sources Sci. Technol.

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The review provides an up-to-date overview and discussion of phenomena related to positive streamer breakdowns in short uniform and non-uniform field (corona) gaps. The terminology used to specify different types of streamer phenomena is critically discussed in light of a unified theory of high-pressure gas discharges describing the sequence of ionization events from initial electron avalanches up to a partial or complete breakdown. The emphasis is given to the understanding of the formation of an active cathode spot by the streamer arrival to the cathode, which is the critical but still obscure phase of the breakdown development. Based on the analysis including a computer simulation model a hypothesis is advanced that also such widely studied and practically important gas discharge phenomena as negative corona Trichel pulses and fast ionization instabilities in cathode regions of high-pressure gas discharges are due to the formation of positive streamers in the immediate cathode vicinity. The proposed hypothesis offers attractive feature of the unification of a wide scale of high-pressure gas discharges within the general class of positive streamer initiated breakdown phenomena. Moreover, it provides indications for further study in the field both by experiment and computer simulations.

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“…These impulses also look very much like those recorded at 10 Torr in dried air (relative humidity <5%) with the same discharge current (10 µA) [20]; moreover, in both cases, the potential drop in the 10-20 µA region is much greater than that for air at atmospheric pressure (for which there is only a decrease of the slope). Because the designation 'streamer' is generally (but not always [25]) reserved for a pressure range around or above the atmospheric one and to distinguish between the classical streamer and this ionizing front taking place at low pressures, we call the latter a pseudo-streamer and, if necessary, the corresponding discharge configuration will be qualified as a streamer-like one.…”

Section: Evolution Along a Fixed Characteristic Curvementioning

confidence: 99%

“…The following study may be performed at every pressure under 250 Torr, but is detailed here for 50 Torr. Let us recall that, at this pressure, a typical current waveform recorded at the plane consists of an initial plateau (a displacement current related to the Ramo-Shockley theorem [25,48]), a considerable conduction peak when the front reaches the cathode and a relatively broad 'shoulder' corresponding to the secondary pseudo-streamer (figure 10).…”

Section: Focalization Of the Pm On A Precise Spot Of The Gapmentioning

confidence: 99%

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Dc point-to-plane discharge in pure oxygen in the 50-760 Torr pressure range

Nicolas

Loiseau

Ercilbengoa

et al. 1998

J. Phys. D: Appl. Phys.

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The present work is a part of a general study dealing with pure gases at pressures in the 50-760 Torr range. This experimental study concerns discharges occurring in oxygen, between a 100 µm curvature radius rhodium point and a stainless steel plane 1 cm distant. A positive dc high voltage is applied to the point using a 0-30 kV, 0-10 mA power supply. Electrical measurements are performed so that voltage-current characteristic curves can be drawn for the whole pressure range. Current impulses are recorded at the earthed plane in each typical regime of the discharge. These electrical impulses are compared with the simultaneous optical signals obtained from a photomultiplier. A focalization on the photomultiplier of various precise spots in the interelectrode gap allows one to get some information about the propagation of an ionizing front from the high-voltage electrode to the grounded plane. From comparison with previous studies, it may be inferred that the glow regime is more difficult to visualize on the characteristic curves than it is in the case of nitrogen. However, 'streamer-like' impulses are observed for oxygen in the whole pressure range, which is not the case for nitrogen. The continuity between these streamer-like impulses and the 'classical' streamers observed at atmospheric pressure seems to be established and confirms the important role played by electronegativity in the inception of ionizing fronts.

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Waveforms of Prebreakdown Primary Streamers in a Short Positive Point-Plane Gap in Air

Cited by 9 publications

References 13 publications

Negative Corona Current Pulses and Cathode Sheath Instabilities in a Short Point-Plane Gap in CO2

Negative Corona Current Pulses and Cathode Sheath Instabilities in a Short Point-Plane Gap in CO2

Streamer breakdown: cathode spot formation, Trichel pulses and cathode-sheath instabilities

Dc point-to-plane discharge in pure oxygen in the 50-760 Torr pressure range

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