Study of Plasma-Wall Interactions using pulsed lasers

摘要

Plasma-wall interactions (PWI) are a common issue in fusion devices like tokamaks and stellarators. Lifetimes of the Plasma Facing Components (PFCs), impurity sources and co-deposition are very important in fusion. These are the main reasons why studies of materials from real fusion machines, retrieved after experimental campaigns as well as studies of PWI in laboratories using various plasma sources (e.g. laser pulses) are of great interest. The accumulation of fuel and dust formation which are problematic both, from safety and operational reasons, should be solved by the development of an effective cleaning method. In this contribution erosion and deposition regions in fusion devices, mechanisms of material transport and main problems with PWI will be introduced together with the description of plasma instabilities which lead to discharge break. Exemplary results of PWI laboratory studies, using laser pulses will be presented. Experimental results of laser-removal of deposits from mixed materials samples using high power density Nd:YAG laser and/or high average power but lower power density Yb:fiber laser will be discussed. The Laser Induced Breakdown Spectroscopy (LIBS) diagnostics which is a potential candidate to monitor the layer composition and fuel retention of fusion device walls will be also presented.