Plasma facing components

Applied Sciences, Inc. has, in the past few years, used the fixed catalyst fiber to fabricate and analyze VGCF-reinforced composites which could be candidate materials for thermal management substrates in high density, high power electronic devices and space power system radiator fins and high performance applications such as plasma facing components in experimental nuclear fusion reactors. These composites include carbon/carbon (CC) composites, polymer matrix composites, and metal matrix composites (MMC). Measurements have been made of thermal conductivity, coefficient of thermal expansion (CTE), tensile strength, and tensile modulus. Representative results are described below. 

Fig. 1.1. ITER cross-section showing (a) main components and (b) the choice of materials for plasma facing components...

Graphite has been chosen only for those plasma facing components which are subject to the highest heat loads because this material is forgiving graphite does not melt - its shape is maintained. The graphite components are not destroyed even with transient heat loads much beyond the acceptable steady state heat flow, thus it is an excellent choice for experiments with a natural tendency to explore the operational limits. 

Using this armor combination, the erosion lifetime of the plasma facing components is expected to meet the goal of sustaining 3,000 full-power discharges of 400 s duration, with about one in ten discharges ending in a disruption. 

Impurity generation by erosion of materials from plasma facing components is an important issue for a fusion device with respect to... 

The relevance of chemical erosion became evident when introducing low Z elements, in particular carbon, for plasma facing components in tokamaks. The erosion yields of chemical processes and sputtering can be of the same order of up to a few percent but show significantly different dependencies physical sputtering has a strong j-dependence, whereas the yield Ych of chemical erosion varies with surface temperature Ts and flux density, as is shown in the following. 

Development of methods to determine the real surface composition of plasma facing components and their consequences on sputtering, reflection and chemical reactivity. 

Since a tokamak or a stellarator represents almost a closed system, the majority of eroded particles must be deposited somewhere in the machine. Therefore, when calculating the life time of plasma facing components it is misleading to consider erosion only. E.g., taking an extreme case on the tip of... 

The data in Fig. 3.20 and similar observations in JET [39,40] imply that a non-negligible amount of the main plasma ELM energy loss may reach plasma facing components (PFCs) in the main chamber of the device and not the divertor target. While this can enlarge the range for ITER oper-... 

Next-step D-T burning fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER), will require several kilograms of tritium [1,2]. While most of the tritium will be contained in the fuel process loop, the interaction of the plasma with plasma-facing components (first-wall armour, limiters, and divertors) will lead to accumulation of tritium in the torus. Based on the amounts and distribution of D retention in TFTR and... 

Tritium Inventory in the Materials of the ITER Plasma-Facing Components... 

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