The researchers of TSC SB RAS studied the processes in materials irradiated with pulsed electron beams

The results of the study conducted by researchers of the Tomsk Scientific Center make it possible not only to better understand the nature of the thermal processes in materials under irradiation, but also to evaluate the use of electron beam machines for solving various production tasks. The paper is published in Coatings (ISSN 2079-6412).

– Any pulsed heating is a combination of two types of heating: surface and volume. If in the first case, the energy of the pulsed beam gradually heats the target layer by layer starting from the surface, then in the second case the heating of the target is observed almost instantly throughout the entire volume, – says the author of the research, Alexey Markov, the head of the TSC SB RAS.

In the course of the work, the melting thresholds of metals for different types of heating with a pulsed electron beams were calculated. Further, these data were used to calculate the melting thresholds of all basic metals widely used in industry, from beryllium to tungsten, in a wide range of beam parameters such as accelerating voltage and pulse duration.

As a result, it was established that the same material, depending on the parameters of the pulsed source of electron beams, can be both fusible and refractory. It was shown that well-known fusible materials can be refractory in some cases, while conversely, the most refractory ones can melt relatively easily if the parameters of the PEBs are changed. For example, tungsten, molybdenum and beryllium under surface heating are the most refractory materials, as it was expected, and under volume heating the situation is different: beryllium, titanium and chromium are the most refractory ones.

The infusibility of metals during pulsed heating shows that heating them to melting temperatures is a difficult task and they can absorb heat during treatment. For example, beryllium is a unique material because it can absorb relatively large amounts of heat without marked increase of temperature while molybdenum, tungsten and chromium do more than three and a half times less.

The results were verified using simulation of the temperature field dynamics during treatment using the HEATPACK-1.0 software package developed at the TSC SB RAS.

The author emphasizes that understanding of the thermal processes in the target material during treatment will help to determine the electron beam machine which is the most suitable for solving a particular production task.

The author states that radiation sources used for the surface heating are mainly used to modify metal surfaces and form surface alloys. So they should not be used for sterilization of medical instruments. And on the contrary, sources for bulk heating are good for liquid sterilization, decontamination, fracture of solids, or microwave radiation generation.

According to the author, a fairly wide variety of pulsed electron beam sources have been designed for various purposes, e.g., generating microwave or X-ray radiation, sterilizing medical materials, processing plant seeds, synthesis of dielectric coatings . Many of them were developed by researchers of the Institute of High Current Electronics SB RAS and the Tomsk Scientific Center SB RAS and are present in the Tomsk Regional Research Equipment Sharing Center of the Tomsk Scientific Center SB RAS.