TY - JOUR

T1 - Problems of molecular beams generation from supersonic flows of rarefied gases in conditions for the formation of clusters and cluster ions

AU - Khudozhitkov, V. E.

AU - Zarvin, A. E.

AU - Kalyada, V. V.

N1 - The research was performed on the equipment of the Center for Collective Use “Applied Physics” of Novosibirsk State University with financial support from the Russian Science Foundation (grant 25-79-30031, https://rscf.ru/project/25-79-30031/) in terms of the experimental study of the features of particle clustering in a supersonic flow exposed to electron action of different energies at different points of the flow (in the nozzle, in the near field, in the core of the jet, in the ionizer of the mass spectrometer), as well as the Ministry of Science and Higher Education of the Russian Federation (FSUS-2025-0008) regarding the validation of diagnostic modeling methods in a condensing medium for the study of neutral and ionized gas flows during supersonic expansion.

PY - 2026/9

Y1 - 2026/9

N2 - This paper describes the methods and methodological problems of forming molecular beams from supersonic flows with clusters, as well as ways to solve these problems. The principles of choosing the optimal nozzle-skimmer distance in various conditions are determined based on the presented diagnostic results of a clustered supersonic argon flow. The processes of scattering and mass selection in neutral clustered argon and nitrogen beams are illustrated, and appropriate explanations are provided. The features of changes in the intensity of monomers in the clustered beam as a function of the stagnation pressure and the nozzle–skimmer distance are established. It is shown that, depending on the geometry of the recording system of the molecular beam, the results in clustered streams can have significant differences. Scattering processes of partially ionized clustered beams are described. The limitations of the ion transportation system to the mass spectrometer detector are indicated. It has been found that the efficiency of focusing cluster ions using applied voltages to the skimmer and collimator decreases with increasing particle masses, as well as the average cluster size. The results of mass spectrometric diagnostics for a clustered flow of argon and a gas mixture of 80%He+20%CH4, recorded using different ionization methods of the gas jet implemented at the LEMPUS-2 facility, are presented. The attractiveness of using methods for gas stream ionization by using a high-voltage electric beam in a jet and an electric discharge in a nozzle diffuser to produce cluster ions is proved. Using the example of the charged particle transport system implemented at the LEMPUS-2 facility, the possibilities of obtaining cluster ions of acceptable intensity are demonstrated.

AB - This paper describes the methods and methodological problems of forming molecular beams from supersonic flows with clusters, as well as ways to solve these problems. The principles of choosing the optimal nozzle-skimmer distance in various conditions are determined based on the presented diagnostic results of a clustered supersonic argon flow. The processes of scattering and mass selection in neutral clustered argon and nitrogen beams are illustrated, and appropriate explanations are provided. The features of changes in the intensity of monomers in the clustered beam as a function of the stagnation pressure and the nozzle–skimmer distance are established. It is shown that, depending on the geometry of the recording system of the molecular beam, the results in clustered streams can have significant differences. Scattering processes of partially ionized clustered beams are described. The limitations of the ion transportation system to the mass spectrometer detector are indicated. It has been found that the efficiency of focusing cluster ions using applied voltages to the skimmer and collimator decreases with increasing particle masses, as well as the average cluster size. The results of mass spectrometric diagnostics for a clustered flow of argon and a gas mixture of 80%He+20%CH4, recorded using different ionization methods of the gas jet implemented at the LEMPUS-2 facility, are presented. The attractiveness of using methods for gas stream ionization by using a high-voltage electric beam in a jet and an electric discharge in a nozzle diffuser to produce cluster ions is proved. Using the example of the charged particle transport system implemented at the LEMPUS-2 facility, the possibilities of obtaining cluster ions of acceptable intensity are demonstrated.

KW - Cluster

KW - Discharge

KW - Electron beam

KW - Mass spectrometry

KW - Molecular beam

UR - https://www.scopus.com/pages/publications/105037650806

UR - https://www.mendeley.com/catalogue/13aee2e1-2fdd-392a-8bd1-e65a9aeca963/

U2 - 10.1016/j.vacuum.2026.115434

DO - 10.1016/j.vacuum.2026.115434

M3 - Article

VL - 252

JO - Vacuum

JF - Vacuum

SN - 0042-207X

M1 - 115434

ER -