Upper Pressure Limit of Ignition

Abstract

ON the basis of their experimental data, Hinshel-wood and Grant¹ arrive at the conclusion that the rupture of the reaction chains in the gas phase is due to ternary collisions, the latter fact being responsible for the existence of the upper pressure limit. A similar view was expressed by me in 1930 as the result of the experimental work carried out at the Leningrad Physical-Technical Institute. As early as then, I believed that the existence of the upper limit could be interpreted only on the assumption of the deactivation process in the gas phase being due to ternary collisions. Indeed, the velocity of a chain reaction is w = n₀/—, where n₀ is the number of initial centres, the probability of rupture, and that of branching. The condition for the existence of an upper limit is — = 0. If both breaking and branching of chains are due to double collisions, the values of and will depend on the same order of the pressure, which leads to the absence of any upper pressure limit of ignition. For the existence of an upper limit, should depend upon a higher order of pressure than. Thus, for example, if the branching of chains required double collisions, their rupture should be brought into relation with ternary collisions.