Abstract
<title>Abstract</title> <p>The mass spectra of supersonic clustered streams of pure methane, helium-methane and argon-methane mixtures flowing into a rarefied space are studied. The features of the recorded mass spectra during the ionization of gas stream particles by the mass spectrometer's own ionizer (method EBMS), a high-voltage electron beam crossing a supersonic stream (method HVEB), and an electric discharge in a nozzle diffuser (method DIN) are studied. It is shown that during the transport of ionized particles in a jet (HVEB and DIN methods) to a mass spectrometer detector (with its own ionizer turned off), ionized clusters are selected by mass due to the privileged focusing of lighter ions by electric potentials on the skimmer and collimating diaphragms. It was found that the addition of buffer gas, argon, slightly slows down the process of cluster formation in methane, while the addition of helium significantly hinders the condensation process. It is determined that the destruction of large clusters in a pure methane stream leads to a greater contribution to the oligomeric component than to the monomeric one, compared, for example, with a helium–methane mixture. It is shown that a high-voltage electron beam, widely used in studies of the gas dynamics of rarefied gases, provides ionization of only a small fraction of the clustered particles in the jet, and therefore is not effective enough to solve the problems of hydrocarbon synthesis. When studying the ionization of a gas stream in a supersonic nozzle diffuser, the presence of a cluster formation process under electron discharge conditions was confirmed. It has been found that the direct use of a mass spectrometer for measurements under these conditions is significantly difficult due to effective mass discrimination. It is shown that this method of electron action on the cluster formation process is nevertheless the most effective and can be used to study the mechanism of electronically stimulated condensation. Optimal conditions for the formation of groups of hydrocarbon compounds have been found, which are the most promising for the subsequent search for technologically justified synthesis solutions.</p>