2218 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 39, NO. 11, NOVEMBER 2011

Streamer Propagation of Positive and NegativePulsed Corona Discharges in Air

Yoshiyuki Teramoto, Yuki Fukumoto, Ryo Ono, and Tetsuji Oda

Abstract—Streamer propagation of positive and negative pulsedcorona discharges is observed using streak and ICCD cameras.The discharge occurs in a 13-mm point-to-plane gap in dry air.In the positive discharge, the primary streamer propagates fromthe point to the plane, and then, the secondary streamer developsfrom the point to the middle of the gap. When the voltage is high,a midgap streamer is also observed. In the negative discharge, theprimary streamer develops from the point to the plane, and then,an anodic channel develops from the plane to the middle of thegap. The velocity and luminous intensity of the primary streamerin the positive discharge increase as the streamer propagates fromthe point to the plane, while those in the negative discharge showan opposite tendency.

Index Terms—air, corona discharge, propagation, streak,streamer.

THE OBSERVATION of streamer propagation is very im-portant to study the radical production mechanism. For

example, ozone is mainly produced in secondary streamersin pulsed positive corona discharges [1], leaving out primarystreamers altogether. For the efficient production of radicals,which is important for the application of streamer dischargesuch as pollution control, the streamer propagation mechanismshould be studied. In this paper, we observe the streamerpropagation in positive and negative pulsed corona dischargesin dry air using streak and ICCD cameras. The effect of polarityon the streamer propagation is investigated.

The discharge occurs in a 13-mm point-to-plane gap placedin a box-shaped reactor of 170 × 74 × 21 mm3. Pulsed volt-age is generated using a spark gap switch. The detail of theexperimental setup can be found in [2]. During the experiment,dry air [N2/O2(20%)] flows through the reactor at a rate of2 L/min under atmospheric pressure. The discharge repetitionrate is 0.3 pulse per second. The discharge is observed usinga streak camera (Hamamatsu, C4742-95) and an ICCD camera(Oriel, InstaSpec V). The optical gate times of the streak andthe ICCD cameras are 100 ns and 100 µs, respectively.

Manuscript received November 19, 2010; revised May 22, 2011; acceptedJune 15, 2011. Date of publication August 4, 2011; date of current versionNovember 9, 2011. This work was supported by a Grant-in-Aid for JapanSociety for the Promotion of Science Fellows.

Y. Teramoto and R. Ono are with the Department of Advanced Energy,The University of Tokyo, Kashiwa 227-8568, Japan (e-mail: teramoto@streamer.t.u-tokyo.ac.jp; ryo-ono@k.u-tokyo.ac.jp).

Y. Fukumoto and T. Oda are with the Department of Electrical Engineer-ing, The University of Tokyo, Tokyo 113-8656, Japan (e-mail: fukumoto@streamer.t.u-tokyo.ac.jp; oda@ee.t.u-tokyo.ac.jp).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TPS.2011.2161490

Fig. 1(a) shows the streak photographs, the ICCD photo-graph, and the V I waveforms for the positive discharge. Thestreak photographs (i)–(iii) show the well-known propagationof the primary and secondary streamers [2], [3]. The primarystreamer propagates from the point anode to the plane cathode,and then, the secondary streamer propagates from the pointanode to the middle of the gap. The secondary streamer isalso observed in the ICCD photograph (brighter filaments). Itshows that the secondary streamer propagates along the primarystreamer channel.

When the voltage is high (V ≥ 32 kV), another type ofstreamer is observed in addition to the primary and secondarystreamers. It is shown in the streak photograph (iv). A luminouszone develops from the middle of the gap where the primarystreamer has a minimum velocity. This is similar to the “midgapstreamer” observed in the low-pressure (50 torr) positive coronadischarge [4]. Our midgap streamer is not observed when theambient air is humidified.

Fig. 1(b) shows the results for the negative discharge. Thestreak photographs (ii)–(iv) show that the primary streamerdevelops from the point to the plane, and then, a luminouszone develops from the plane to the middle of the gap. Thissecondary luminous zone is similar to the “cathodic channel”observed in the positive streamer, where the cathodic channeldevelops from a cathode plane [5]. Hereafter, the secondaryluminous zone developed from the anode plane in Fig. 1(b)is called “anodic channel.” The anodic channel is not alwaysobserved. The frequency of its appearance increases with theapplied voltage. The streak photograph (i) is the result whenthe anodic channel does not appear. The anodic channel is alsoobserved in the ICCD photograph (brighter filaments). It showsthat the anodic channel propagates along the primary streamerchannel. In the streak photographs (ii)–(iv), a weak emissionnear the point cathode is also observed along with the anodicchannel.

The propagation of the primary streamer is quite differentbetween the positive and negative discharges. In the positivedischarge, the velocity and luminous intensity of the primarystreamer increase as the streamer propagates from the point tothe plane. On the other hand, in the negative discharge, theydecrease as the streamer propagates from the point to the plane.The average velocity of the positive streamer is faster than thatof the negative streamer at the same amplitude of dischargevoltage. This result is in agreement with [6].

The propagation length of the secondary streamer fromthe point anode increases linearly with the discharge voltage[2]. Similarly, the propagation length of the anodic channelfrom the plane increases linearly with the discharge voltage.

0093-3813/$26.00 © 2011 IEEE

TERAMOTO et al.: STREAMER PROPAGATION OF PULSED CORONA DISCHARGES IN AIR 2219

Fig. 1. Streak photographs, ICCD photographs, and V I waveforms of (a) positive and (b) negative discharges. The emission intensities of all photographs areproperly normalized. The streak and ICCD photographs use different colormaps.

It is 6.9, 9.3, and 11.3 mm for −24, −28, and −32 kV,respectively.

Briels et al. [6] observed positive and negative pulsed stream-ers using an ICCD camera. Their result was somewhat differentfrom ours. In [6], the midgap streamer of the positive dischargeand the anodic channel of the negative discharge were notobserved. It indicates that the streamer propagation dependson discharge conditions such as voltage, gap length, dischargecircuit, etc. Further study is required for understanding thepropagation of positive and negative streamers.

ACKNOWLEDGMENT

The authors would like to thank Prof. K. Hidaka andProf. A. Kumada at the University of Tokyo for their supportin the use of the streak camera.

REFERENCES

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[2] R. Ono and T. Oda, “Formation and structure of primary and secondarystreamers in positive pulsed corona discharge-effect of oxygen concentra-tion and applied voltage,” J. Phys. D, Appl. Phys., vol. 36, no. 16, pp. 1952–1958, Aug. 2003.

[3] E. Marode, “The mechanism of spark breakdown in air at atmosphericpressure between a positive point and a plane. I. Experimental: Natureof the streamer track,” J. Appl. Phys., vol. 46, no. 5, pp. 2005–2015,May 1975.

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