Progression features of a stepped leader process with four grounded leader branches

2007 ◽  
Vol 34 (6) ◽  
Author(s):  
Xiushu Qie ◽  
Xiangzhen Kong
Keyword(s):  
Leader Process

The Leader Process

2017 ◽  
pp. 203-260
Author(s):  
E.M. Bazelyan ◽  
Yu. P. Raizer
Keyword(s):  
Leader Process

Multivariate extremal processes, leader processes and dynamic choice models

1990 ◽  
Vol 22 (2) ◽  
pp. 309-331 ◽  
Author(s):  
Sidney Resnick ◽  
Rishin Roy
Keyword(s):  
Transition Probabilities ◽  
Homogeneous Case ◽  
Dynamic Choice ◽  
Underlying Distribution ◽  
Extremal Process ◽  
Time Dependent Behaviour ◽  
Stationary Transition ◽  
Dynamic Choice Models ◽  
Dependent Behaviour ◽  
Leader Process

Let (Y(t), t > 0) be a d-dimensional non-homogeneous multivariate extremal process. We suppose the ith component of Y describes time-dependent behaviour of random utilities associated with the ith choice. At time t we choose the ith alternative if the ith component of Y(t) is the largest of all the components. Let J(t) be the index of the largest component at time t so J has range {1, …, d} and call {J(t)} the leader process. Let Z(t) be the value of the largest component at time t. Then the bivariate process (J(t), Z(t)} is Markov. We discuss when J(t) and Z(t) are independent, when {J(s), 0<s≦t} and Z(t) are independent and when J(t) and {Z(s), 0<s≦t} are independent. In usual circumstances, {J(t)} is Markov and particular properties are given when the underlying distribution is max-stable. In the max-stable time-homogeneous case, {J(et)} is a stationary Markov chain with stationary transition probabilities.

scholarly journals Continuous and Discontinuous Streamer Leader Propagation Phenomena under Slow Front Impulse Voltages in a 10-meter Rod-Plane Air Gap

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2636 ◽  
Author(s):  
Wahab Ali Shah ◽  
Hengxin He ◽  
Junjia He ◽  
Yongchao Yang
Keyword(s):  
Quantitative Research ◽  
High Speed ◽  
Large Scale ◽  
Physical Phenomenon ◽  
Ccd Camera ◽  
Leader Development ◽  
Charge Coupled Device ◽  
The Comparative Study ◽  
Leader Process ◽  
Observation Results

Investigation of positive streamer-leader propagation under slow front impulse voltages can play an important role in the quantitative research of positive upward lightning. In this work, we performed a large-scale investigation into leader development in a 10-m rod–plane gap under a long front positive impulse. To describe the leader propagation under slow front impulse voltages, we recorded the leader propagation with a high-speed charge coupled device (CCD) camera. It is important to figure out this phenomenon to deepen our understanding of leader discharge. The observation results showed that the leader mechanism is a very complex physical phenomenon; it could be categorized into two types of leader process, namely, continuous and the discontinuous leader streamer-leader propagation. Furthermore, we studied the continuous leader development parameters, including two-dimensional (2-D) leader length, injected charge, and final jump stage, as well as leader velocity for rod–plane configuration. We observed that the discontinuous leader makes an important contribution to the appearance of channel re-illuminations of the positive leader. To clarify the above doubts under long front cases, we carried out extensive experiments in this study. The comparative study shows better results in terms of standard switch impulse and long front positive impulse. Finally, the results are presented with a view toward improving our understanding of propagation mechanisms related to restrike phenomena, which are rarely reported.

scholarly journals Characteristics of Regular Pulse Bursts Generated From Lightning Discharges

2021 ◽  
Vol 9 ◽  
Author(s):  
Wang Yanhui ◽  
Fan Xiangpeng ◽  
Wang Tuo ◽  
Min Yingchang ◽  
Liu Yali ◽  
...  
Keyword(s):  
Central Charge ◽  
Three Dimensional ◽  
Pulse Amplitude ◽  
Pulse Period ◽  
Regular Pulse ◽  
Lightning Discharges ◽  
Maximum Proportion ◽  
The Difference ◽  
Pulse Polarity ◽  
Leader Process

In this work, we studied the waveforms of all lightning discharges from about 15 min. Eighty-three percent of all lightning discharges contain particular waveforms called regular pulse bursts (RPBs), which have regular microsecond-scale electric or magnetic field pulses. Maximum proportion of RPBs occur in middle or rear of lightning discharges. Prior to or after RPBs, there is always a chaotic pulse period. The analysis indicated that RPBs are caused by a secondary discharge in the fractured old breakdown channel, likeness to dart-stepped leader occuring in negative cloud-to-ground discharge (-CG). Four types of RPBs, namely, category of normal RPBs, category of back RPBs, category of symmetric RPBs, and category of reversal RPBs, were sorted in the light of the evolution of the pulse amplitude, interval between neighboring pulses and pulse polarity. In addition, the difference between normal RPBs and back RPBs was considered to be caused by the distance between neighboring charge pockets and the magnitude of the charge in every charge pocket. The symmetric RPBs were considered to be caused by a discharge channel with a large central charge area. Reversal RPBs were considered to be caused by a bending channel or superposition of two or more RPBs. We located some RPBs in a typical intra-cloud flash (IC) in three-dimensional. The analysis showed that the developing velocity of RPBs ranged from approximately 1.2 × 106 m/s to 3.0 × 106 m/s, which slower less than both of the dart leader or dart-stepped leader process from previous studies. And we found it is several meters to dozens of meters that the lengths range of discharge step which between two adjacent pulses.

The pilot streamer in lightning and the long spark

1953 ◽  
Vol 220 (1140) ◽  
pp. 25-38 ◽  
Keyword(s):  
Unit Length ◽  
Average Radius ◽  
Electron Avalanche ◽  
Free Electrons ◽  
Step Process ◽  
Starting Point ◽  
Electrode Space ◽  
Current Densities ◽  
Spark Breakdown ◽  
Leader Process

The absence of significant pulsations on records of the electrostatic field of the stepped leader further establishes the existence of the pilot streamer, which must carry approximately the same current (320 A) and charge per unit length as the leader behind it. Pulsation theories of the stepped leader process are therefore inadmissible. The average radius of pilot and leader streamers in lightning is found to be 2⋅5 m , thus excluding single-avalanche theories of the step process. A new explanation of the step process is given, according to which the charge on the pilot progressively reduces the field at its starting-point in front of the arrested leader until current ceases, owing to the disappearance of free electrons by capture. A positive ‘electrode’ space charge then develops at this point and in 3 μs creates a field sufficiently strong for the development of a fast step streamer which overtakes the whole pilot in less than 1 μs and converts a new section of the channel into a conductor with are characteristics. The pilot streamer processes in lightning and the long spark have nearly identical velocities, current densities, channel field strengths and ratios of length to radius; it is concluded that they are produced by the same mechanism. It is suggested that the preliminaries to spark breakdown between 1 and 3 MV involve a transition from the narrow electron avalanche to the broad pilot process.

Leader process in 3D observed by VLF/LF broadband interferometer

2012 ◽  
Author(s):  
Y. Takayanagi ◽  
M. Akita ◽  
Y. Nakamura ◽  
S. Yoshida ◽  
T. Morimoto ◽  
...  
Keyword(s):  
Leader Process
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