Speaker
Description
See full abstract here http://ocs.ciemat.es/EPS2019ABS/pdf/P5.3007.pdf
The implementation of thermonuclear technology requires the development and formation of the reliable, long-lived nuclear fusion systems that will be able to guarantee the safe operation. Meanwhile, interaction plasma with divertor and the reactor first-wall elements leads to damage of their surfaces via erosion process and to generation dusty in the reactor zone [1]. The dust accumulation in reactor can cause an explosion. Thus, it is necessary to study such type process in order to limit undesirable implications.
To check the erosion and deposition processes in the reactor, a non-contact method with high spatial resolution and high accuracy in geometry measurements is required. According to [2], these measurements can be realized by using means dual wavelength speckle interferometry providing record of topogram. The method works with optical rough surfaces and has good precision (100 nm). Although high-quality topogram might be obtained by the approach, there are a lot of factors that negatively influence on the recording process. Therefore, to develop a reliable interferometer for real conditions, we have to spend a lot of time for hardware debugging. Thus, to shorten a design period, it is necessary to represent erosion in reactor via imitation. In order to inspect erosion process under normal condition in air, a gas-discharge test-device based on the removable electrode systems with the colliding surface discharges [3] was proposed. In contrast to [3], the electrode system has a high-resistive, diffusely reflecting coating on a fiber-glass plastic, dielectric barrier. The presence of diffusely reflecting coating has two consequences. Firstly, the coating provides registration of quality speckle-interferograms. Secondly, the colliding surface discharges are excited in the porous medium of the reflecting layer. In experiment, the surface discharge due to heating of electrode system evaporates the bonding medium of fiberglass plastic. As a result, the erosion zone with area of about several square centimeters and depth from ten micron to 0.1 mm forms. So, the test-device allowed us to observe both thermal deformation of electrode system and surface erosion of dielectric barrier. The device may be useful for testing of digital speckle-interferometers in the study of plasma-wall interaction.
References
[1] Coenen J.W. et al. (2017). Nuclear Materials and Energy, V.12 - P.307-312.
[2] Franson M. (1980). Optics of speckles. Moscow: Mir.[In Russian]
[3] Ivchenko A.V., et al. (2012). Europhysics Conference Abstracts, V.36F-4p
