Mono-block cooling device component
A cooling device component in a mono-block design comprising a plasma facing material (PFM) heat shield made from tungsten, a tungsten alloy, a graphitic material or a carbidic material which is provided with a through-hole. A cooling pipe for carrying coolant is connected at the through-hole. With its specific combination of materials, the invention shows promising results in avoiding cracking and loss of the heat shield when exposed to heat fluxes higher than 10mW/m2.
The invention is a cooling device component that is highly stable thermally and incorporates a passage for conducting coolant. The device comprises at least one heat shield made from tungsten, a tungsten alloy, a graphitic material or a carbidic material. Typical examples of such cooling system components are first wall components for fusion reactors such as a divertor and limiter that are exposed to thermal loads higher than 10 mW/m2. Such a heat shield requires plasma-facing materials with a high melting and sublimation point, and a high resistance to physical and chemical sputtering. In addition they need to have a high thermal conductivity, low neutron-activation capacity and sufficient strength. Tungsten, a tungsten alloy, a graphitic material or a carbidic material meet these diverse and sometimes conflicting requirements best. The selection of a specific material for the construction of the heat shield should take into account the requirements of the particular application. In Fig.1 a qualification prototype for nuclear fusion applications is presented. It consists of both Carbon Fiber Composite (CFC) monoblocks (straight section) and tungsten monoblocks (curved section). In the mono-block design the cooling device consists of a cooling water pipe that is wrapped by a heat shield of plasma facing material. The shield is integrally joint to a structural part consisting of a Fe-, Ti- or Ni-based material, having a tensile strength > 300 MPa at room temperature and a specific electric resistance > 0.04 Ohm mm2m-1. This avoids both crack initiation in brittle plasma facing materials and the consequent loss of the heat shield material, which would ultimately lead to failure of the heat shield.
Innovations & Advantages
The invention described above is a cooling device component in a mono-block design comprising a plasma facing material (PFM) heat shield made from tungsten, a tungsten alloy, a graphitic material or a carbidic material. This is provided with a through-hole with a pipe for a cooling fluid circulation. In this manner it meets the requirements to avoid cracking and failure of the heat shield from both physical and mechanical stresses in first-wall components in fusion reactors. The invention solves a problem that has until now prevented the implementation of shield components at large scale.
Current and Potential Domains of Application
This technology has been identified in the framework of the FUTTA (Fusion Technology Transfer Action) project, funded by the European Commission, and with the collaboration of Eurofusion.
It constitutes an example for a promising technology that is expected to provide a substantial transfer potential from the Nuclear Fusion domain towards other domains, including Space.