Detection of temporary capillary stability in EB beam-deflection techniques using X-ray self-illumination

• Published in: Vacuum 2023-07, Vol.213, p.112121, Article 112121
• Main Authors: Gach, S., Akyel, F., Olschok, S., Reisgen, U.
• Format: Article
• Language: English
• Subjects: Capillary inertia; Capillary-behaviour; Electron beam welding (EBW); High-speed recording; Pinhole camera (camera obscura); Secondary X-ray analysis
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2023.112121

A deeper understanding of the temporal behaviour of capillaries enables the improvement of modern beam welding processes, e.g. the application of the multi-bath or multi-process technique in electron beam welding. The temporal capillary behaviour in an Electron Beam (EB) multi-bath welding process can be analysed at different beam deflection frequencies by means of secondary X-ray. This is visualised by X-rays which are generated during beam-material interaction in the capillary and can be visualised as an upside-down image on a scintillator screen via a pinhole camera. The analysis of the high-speed images allows conclusions regarding the inertia of a temporarily unheated EB capillary. This paper shows that with increasing deflection rate the collapse of capillary decreases while at a deflection rate of 1000 Hz no collapse in capillary depth can be detected. •A basic visualisation of the capillary behaviour by X-ray self-illumination is possible.•Recording rates of up to 10 kHz can be achieve with the presented set-up.•Using automated image recognition, the capillary depth can be measured in each individual image of the high-speed recordings.•It is found that a temporarily heated capillary partially collapses in the non-heated phases.•With increasing deflection frequency the capillary collapse is reduced up to the point of 1000 Hz.•The inertia of the capillary can be determined to 1 ms under the given conditions.