Tokamak wall may be stronger than thought

Too strong a devastating effect on the walls of a fusion reactor capable paradoxically better protect it from the “costs” of nuclear fusion.

Work on the reactor ITER , a major international project on nuclear fusion, is in full swing. Along the way, sometimes it turns out that the prospects for ITER may be worse than expected, and now it seems it is time for the news of the opposite persuasion.

“Heart” ITER – plasma confinement chamber, tungsten wall which, despite the lack of direct contact with the plasma itself, subjected to heavy loads.

In this experimental chamber as much as modulated conditions inside the reactor of ITER. (Here and below illustration CCFE.)

Physics headed by Gregory De Temmermanom ( Gregory De Temmerman ) of the Institute of Fundamental Research Matter (The Netherlands), studying the processes of interaction between plasma and the walls of such reactors are focusing particularly powerful energy emissions that occur in nuclear fusion in a thermonuclear fuel and take out the cooling hydrogen atoms of the zone where the reaction occurs.

The fact is that although the bursts on the superficiality of the confined plasma, representing the greatest threat to the walls, it’s already familiar, their power is much less than the future iterovskoy as energy retention in modern tokamaks is quite different. So for a long time discussed the view that a further increase in capacity retention may lead to the need to frequently change the wall elements.

However, simulations and experiments conducted by European scientists, give reason to expect rather the opposite. As it turned out, the more energy in the form of hydrogen atoms directed to tungsten walls, the less their number reached.

Moreover, the camera, to capture events that occur with samples of tungsten, checked the light from hydrogen atoms whenever splash reached tungsten. According to physicists, tungsten, able to absorb only a certain number of hydrogen atoms in collisions additional atomic nuclei began to lose those that were already inside it. Thereby it is rid of the difference compared with absorbed energy.

Emissions from the core fusion reactor can reach tungsten walls, but this impact is not always exclusively negative.

In doing so, the gaseous envelope did not give the “language” of the plasma to reach the tungsten in one compact group. Energy burst is distributed over and came to the cloud of tungsten in a relatively mild form of a general increase in temperature.

In other words, despite the fact that the energy spent on the initiation and maintenance of fusion in ITER, can reach 50 MW (ie instantaneous load wall reactors Surge is gigawatt per square meter), the newly identified mechanism of “natural self-defense” tungsten means that wall of the reactor does not become a consumable and with increasing load, in contrast, may increase its resources.

It is unclear exactly how the results of this study do not concern the walls, and that part of ITER, which will arrive still hot products synthesis after cycle, but scientists are soon going to analyze it and.
Study report will be published soon in the journal Applied Physics Letters .

Prepared according to the Institute of Fundamental Research matter .