Initiation of ignition of a combustible gas mixture in a closed volume by the radiation of a high-power pulsed CO₂laser

Fast combustion waves and chemi-ionization processes in a flame initiated by a powerful local plasma source in a closed reactor

“…These frames clearly demonstrate the existence of three characteristic phases observed in all experiments upon the initiation of combustion in closed tubes by high-power electric discharges [1,2,6,8]. These are as follows: the first (initial) phase of a relatively short ( t 1 ≤ 10 µs) radiation from a spark excited in the laser beam focus (figure 6(1)); the second phase called, following combustion physics terminology, the 'induction' time, which is a relatively long ( t 2 ≤ 1.0 ms) period preceding the volume combustion of the gas mixture in the reactor (figure 6(2), (3)); and finally, the third phase of the fast ('explosive') volume combustion of the combustible mixture, which is characterized by a bright burst of duration t 3 ≈ 5-10 ms (figure 6(5)- (8)).…”

“…Figure 2 shows the schematic of a reactor with the high-current slipping surface discharge initiation of combustion. The chamber (2) in the reactor is the same as that shown in figure 1. The chamber is evacuated to a pressure of p ≤ 0.1 Torr and filled with a working stoichiometric CH 4 : O 2 gas mixture at a pressure of p = 180 Torr.…”

“…The combustion was initiated by localized high-power discharges in which energy was released in small volumes as compared with a chamber volume. These include laser sparks, which are excited on the surface of solid target [1], direct laser heating in the focal spot [2], microwave discharges [3,4] and highcurrent slipping surface discharges [5][6][7]. In [8], the first results on a laser spark freely localized in a reactor chamber and working as a combustion igniter were presented.…”

“…In some papers (e.g. [1][2][3][4][5][6]), these objects are called 'long-lived plasmoids'. In other investigations, brightly glowing long-lived objects that run away from the location of the energy release (their place of origin) are termed 'plasma bullets', 'plasma plumes' or 'plasma balls' [9][10][11][12][13][14].…”

“…The intent of this work was to find information (in addition to that presented in [1][2][3][4][5][6][7][8]) about the structure and dynamics of the formation of flames initiated by powerful discharges excited in a local small area of a reactor chamber as well as to acquire results on the role of chemi-ionization processes in the ignition of combustion and in the parameters of a developed flame.…”