Journal of Siberian Federal University. Engineering & Technologies / Measurement of the Current Density Distribution of the Electron Beam Welding Over Its Cross Section

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Issue
Journal of Siberian Federal University. Engineering & Technologies. 2023 16 (8)
Authors
Semenov, Yuriy I.; Alyakrinskiy, Oleg N.; Devyataikina, Tatyana A.; Kosachev, Mikhail Yu.
Contact information
Semenov, Yuriy I. : Budker Institute of Nuclear Physics of Siberian Branch Russian Academy of Sciences Novosibirsk, Russian Federation; ; Alyakrinskiy, Oleg N.: Budker Institute of Nuclear Physics of Siberian Branch Russian Academy of Sciences Novosibirsk, Russian Federation; Devyataikina, Tatyana A. : Budker Institute of Nuclear Physics of Siberian Branch Russian Academy of Sciences Novosibirsk, Russian Federation; Novosibirsk State University Novosibirsk, Russian Federation; Kosachev, Mikhail Yu. : Budker Institute of Nuclear Physics of Siberian Branch Russian Academy of Sciences Novosibirsk, Russian Federation
Keywords
electron beam welding; electron beam profile; measurement of the electron beam profile; measuring grid; current density distribution of the electron beam of electron beam welding over its cross section
Abstract

In the process of electron-beam welding, the correct selection of the size of the electron beam spot at the junction of the structures to be welded, the location of the focus of the electron beam relative to the “junction surface – vacuum” boundary, and the distribution of specific power over the beam cross section are of great practical importance. The purpose of the work is to present a method for measuring the current density distribution of an electron beam of electron beam welding over its cross section, which consists in oscillography of the electron current passing through a narrow measuring slit of a metal plate into a Faraday cup with a fast sweep of the measured electron beam across the measuring slits. The presented method will make it possible to find the position of the focus of the welding electron beam, determine the size of the electron beam profile in the required place of the welding beam trajectory, and also automate the process of measuring these parameters of the welding electron beam. With this method of measurement, the measurement accuracy deteriorates due to the fact that the value of the current of electrons reflected from the Faraday cup is subtracted from the useful signal of the Faraday cup, and thermionic electrons from the measuring grid are added when operating at a high level of the measured current. To minimize their influence, an additional grating shield electrically connected to the Faraday cup was used. The measured welding current creates a high thermal load on the measuring grating, so the beam is scanned along it at the fastest possible speed, which is allowed by the bandwidth of the scanning system with minimal nonlinearity. The grid is made of refractory tantalum. The main part of the thermal load of the measured current pulse outside the beam sweep time is taken by massive copper screens, one of which has the shape of a grating, the slots of which are wider than those of the measuring grating. This method was used to measure the distribution of the current density of a source of an electron beam with an energy of 90 keV in the range from 1 mA to 80 mA. The proposed method allows measuring the current density distribution of the electron beam of electron beam welding over its cross section with an accuracy of ±10 %

Pages
922–931
EDN
MQXIEM
Paper at repository of SibFU
https://elib.sfu-kras.ru/handle/2311/152317

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