A seminar given by
Dr. Mykola IALOVEGA
Research Associate at the University of Wisconsin–Madison (USA) and in the Plasma Edge Physics with 3D Boundaries group
titled:
Development of Additive Manufacturing Methods of Plasma-Facing Components for Novel Magnetic Fusion Confinement Devices
Abstract: This talk will give an overview on the development of cold spray coatings for functional surfaces of plasma-facing components, specifically, for the novel magnetic confinement fusion devices which are now under construction in Wisconsin, US. Wisconsin HTS Axisymmetric Mirror Experiment (WHAM) is a result of a public-private partnership between the UW-Madison, MIT and Commonwealth Fusion Systems (CFS) to build and operate a compact, high-field mirror device and demonstrate a pathway to a commercial axisymmetric tandem mirror for production of grid—scale electrical power, hydrogen and more. Currently in its final construction phase to achivev pirst plasma, WHAM will utilize REBCO high temperature supercondicting coils (17 T mirrors) with the bore radius of 5.5 cm to confine hot and dense plasmas created using high frequency ECH. RF heating scenario and NBI injecttion will be used for creating fast sloshing ions. Quasi-stationary plasmas (plasma duration >> ion slowing down and characteristic confinement times) will be created with electron temperatures of 1 keV, average ion energies of 20 keV and densities that approach the plasma pressure limit. One of the WHAM’s technilogy missions is to demonstrate advanced particle hadling techniques by utilizing non-evaporatable Tantalum (Ta) gettering interface for effective neutral pressure reduction in the plasma edge which will limit loses associated with charge-exchange and improve the overal plasma performance. This objective is being achieved by developing the solid-state, high-velocity powder-particle-impact-based process—known as cold spray—to create Tantalum coatings on Stainless Steel (SS) substrates. Several cold spray parameters have been tested to achive dense and well-adhered coatings with minimal porosity level. Recent plasma exposure and subsequent annealing experiments have demonstrated the ability of the coatings to withsdand the impact of a high particle fluence (3e25 D/m2) and high surface temperature while maintaing the integrity, surface and bulk morphology of the coatings. Thermal desorption experiments performed in the collaboration with the PIIM laboratory (Aix-Marseille University) revealed the high Hydrogen storage capacity of the coatings (more than two orders of magnitude compared to sintered Tungsten exposed to the same D implantation conditions). Finally, tests of a large-scale Ta cold-sprayed PFC featuring a heating functionality for reguating Hydrogen adsorption and release is underway at the UW-Madison.
In addition, this research provides an expertise on the additive manufacturing options for functional first-walls and divertor components for stellarators and tokamaks. For example, the Helically Symmetric eXperiment (HSX) device at the UW-Madison—a small-scale stellarator—is planned to be upgraded with a significant heating power (up to 800 kW of injected power and yielding plasma densities up to 1e19 m^-3) and a devertor for testing the non-resonant divertor concept in detached plasma conditions. It is proposed to 3D print parts the HSX and utilize the cold spray technology for adding functionality to the PFCs of the device.
Bio: BSc and MSc, Physics, V.N. Karazin Kharkiv National University, Ukraine, 2015; MSc, Nuclear Engineering, Stuttgart University (Germany) and Ghent University (Belgium), 2017; PhD, Plasma Physics and Materials Science, CNRS, Aix-Marseille University and CEA Cadarache (France), 2021. Find more information here. 
