Potential design problems for ITER fusion device

Abstract

The international thermonuclear experimental reactor (ITER) is a worldwide project currently being built in France for the demonstration of the feasibility of thermonuclear technologies for future realization of successful commercial fusion energy. ITER is of the tokamak based design using strong magnetic fields to confine the very hot plasma needed to induce the fusion reaction. Tokamak devices are currently the front leading designs. Building a successful magnetic fusion device for energy production is of great challenge. A key obstacle to such design is the performance during abnormal events including plasma disruptions and so-called edge-localized modes (ELMs). In these events, a massive and sudden release of energy occurs quickly, due to loss of full or partial plasma confinement, leading to very high transient power loads on the reactor surface boundaries. A successful reactor design should tolerate several of these transient events without serious damages such as melting and vaporization of the structure. This paper highlights, through comprehensive state-of-the-art computer simulation of the entire ITER interior design during such transient events, e.g., ELMs occurring at normal operation and disruptions during abnormal operation, potential serious problems with current plasma facing components (PFCs) design. The HEIGHTS computer package is used in these simulations. The ITER reactor design was simulated in full and exact 3D geometry including all known relevant physical processes involved during these transient events. The current ITER divertor design may not work properly and may requires significant modifications or new innovative design to prevent serious damage and to ensure successful operation.

New proposed ITER divertor design using carbon insert on tungsten to mitigate ELMs and secondary radiation effects on nearby components

“…Our new efficient Monte Carlo algorithms can detect all incident particles (charged particles and photons) at any spatial point and time moment inside the entire ITER 3D device geometry and then calculate the energy fluxes (particles and photon radiation) from both the escaped core plasma and from the re-radiated photons from the developed secondary plasma. Recently, we reported about the critical heating spots on the tungsten divertor components during the ELMs and disruptions 6 . In this work, we simulated the same 1 ms ELM and disruption when using thin carbon insert within the tungsten divertor and compared with the pure tungsten heat loads simulations.…”

“…This melting spot appears due to insufficient secondary plasma shielding of the scattered particle showers of the incident core plasma in this area at the time t = 0.65 ms. This damage problem of the dome surface (#5) due to melting during the ELM 6 will be fully avoided with installation of a carbon insert (Fig. 4 a).…”

“…We have developed comprehensive multidimensional models for the integrated simulation of the escaped core plasma particles flow, detail energy deposition, and interaction with the divertor and nearby components. The evolution of the escaped core plasma particles is simulated in 3D realistic ITER geometry in the presence of both the complex magnetic and electric fields starting from the last closed flux surface (LCFS) through the entire scrape-off layer (SOL) area and through the penetration depths inside the divertor components 5 , 6 .…”

Resonant Ion Confinement Fusion Concept

“…Nevertheless, tokamaks still have to overcome some challenges, namely the possibility of suffering disruptions, the existence of edge localised modes (ELMs) and the intrinsic pulsed working, on top of the possible impurity accumulation, (as from Ref. [4]). Turbulence will be also playing a major role degrading the Tokamak plasma confinement.…”

Deposition, Morphological, and Mechanical Evaluation of W and Be-Al2O3 and Er2O3 Co-Sputtered Films in Comparison with Pure Oxides

“…It is well known that the fusion research community is conducting extensive studies for addressing different drawbacks to assist the long-term functionally and successful realization of commercial operation of fusion reactors. The inventory and control of tritium and material embrittlement by hydrogen isotopes exposure are amongst commonly addressed issues related to the development of plasma-facing materials (PFC) [1,2]. The tritium inventory and control are not straightforward to be addressed due to several materials constraints imposed by future nuclear fusion reactor designs and configurations.…”