Thermo-mechanical analysis of a micro-engineered tungsten-foam armored IFE FW

The high average power laser (HAPL) program goal is to develop a laser inertial fusion reactor using a solid first wall (FW). The FW of the inertial fusion energy (IFE) chamber is exposed to high energy photon, particle, and neutron fluxes at frequency of several Hz. The feasibility of using a micro-engineered refractory metals, such as tungsten foam as a solid FW armor is investigated. Refractory foams are a new class of materials with very limited thermo-mechanical property databases. Elastic properties of tungsten foams are not readily available, particularly at high temperatures. To estimate high-temperature elastic properties of tungsten foams, a three-dimensional finite-element model of tungsten foam was developed. True stress strain curves of tungsten foams at elevated temperatures were developed as a function of characteristic foam properties and compared with measured values. The thermo-mechanical response of the tungsten-foam armored FW was analyzed using a detailed three-dimensional finite element model. The thermo-mechanical response of a tungsten-foam protected first wall to a typical IFE pulse is presented. It is shown that the W foam armor can be tailored to meet the thermo-mechanical stress requirements of an IFE solid wall design.