Contrib. Plasma Phys. 45, No. 2, 118 – 129 (2005) / DOI 10.1002/ctpp.200510012 Investigation of the Inﬂuence of Overvoltage, Auxiliary Glow Current and Relaxation Time on the Electrical Breakdown Time Delay Distributions in Neon ˇ C. A. Maluckov ∗1 , J. P. Karamarkovi´ c ∗∗2 , and M. K. Radovi´ c ∗∗∗3 1 Technical Faculty in Bor, University of Belgrade, Vojske Jugoslavije 12, 19210 Bor, Serbia and Montenegro 2 Faculty of Civil Engineering and Architecture, University of Niˇ s, Aleksandra Medvedeva 14, 18000 Niˇ s, Serbia and Montenegro 3 Faculty of Sciences and Mathematics, University of Niˇ s, PO Box 224, 18001 Niˇ s, Serbia and Montenegro Received 30 November 2004, accepted 22 January 2005 Published online 14 March 2005 Key words Electrical breakdown in neon, time delay distribution, Convolution model for time delay distribu- tion, Monte-Carlo method, statistical time delay, formative time delay. PACS 52.80.Hc, 02.50.Ng Results of the statistical analysis of the electrical breakdown time delay for neon-ﬁlled tube at 13.3 mbar are presented in this paper. Experimental distributions of the breakdown time delay were established on the basis of 200 successive and independent measurements, for different overvoltages, relaxation times and auxiliary glows. Obtained experimental distributions deviate from usual exponential distribution. Breakdown time delay distributions are numerically generated, using Monte-Carlo method, as the compositions of the two independent random variables with an exponential and a Gaussian distribution. Theoretical breakdown time delay distribu- tion is obtained from the convolution of the exponential and Gaussian distribution. Performed analysis shows that the crucial parameter that determines the complex structure of time delay is the overvoltage and if it is of the order of few percentage, then distribution of time delay must be treated as an convolution of two random variables. c  2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Electrical breakdown in gases represents the transition of gases from dielectric to conducting state. The electrical breakdown of gases has very signiﬁcant stochastic nature. Investigation of the statistical nature of the electrical breakdown starts with the Zuber [1] and von Laue [2] (1925) and is developed by many authors [3, 4, 5]. The theory is established on the presumption of the Townsend breakdown mechanism [6]. For small pressure and small overvoltages, when the inﬂuence of the space charge is neglected, Townsend theory is applicable. Breakdown criterion according to Townsend theory is: γ  exp   d 0 αdx  - 1  =1, (1) where α is the primary ionization coefﬁcient and γ the effective secondary ionization coefﬁcient which includes all secondary processes. The electrical breakdown mechanism in gases can be considered as a combination of two distinct processes. First process corresponds to the occurrence of one or more physical events which lead to creation of an initial electron. This is the Poisson random process, and time interval to electron appearance is statistical time delay t S . Thus, the statistical time delay t S is characterized with the exponential distribution f (t S ) = exp(-t/ t S )/ t S ∗ Corresponding author: e-mail: cmaluckov@eunet.yu, Phone: +381 30 424 555, Fax: +381 30 421 078 ∗∗ e-mail: ﬁzika@gaf.ni.ac.yu ∗∗∗ e-mail: mkradovic@junis.ni.ac.yu c  2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim