Development of comprehensive and integrated models for inertial fusion cavity dynamics.

The chamber walls in inertial fusion energy (IFE) reactors are exposed to harsh conditions following each target implosion. Key issues of the cyclic IFE operation include intense photon and ion deposition, wall thermal and hydrodynamic evolution, wall erosion and fatigue lifetime, and chamber clearing and evacuation to ensure chamber conditions prior to target implosion. Several methods for wall protection have been proposed in the past, each having its own advantages and disadvantages. These methods include bare walls, gas-filled cavities, and liquid walls/jets. We have developed detailed models for reflected laser light, emitted photon, and target debris deposition and interaction with chamber components and implemented them in the comprehensive HEIGHTS software package. The hydrodynamic response of gas-filled cavities and photon radiation transport of the deposited energy has been calculated using new and advanced numerical techniques. Fragmentation models of liquid jets as a result of the deposited energy have also been developed, and the impact on chamber clearing dynamics has been evaluated. The focus of this study is to critically assess the reliability and the dynamic response of chamber walls in various proposed protection methods in IFE systems. Of particular concern is the effect on wall erosion lifetime of various erosion mechanisms, such as vaporization, chemical and physical sputtering, melt/liquid splashing and explosive erosion, and fragmentation of liquid walls. Mass loss and fragmentation in the form of macroscopic particles can be much larger than mass loss due to surface vaporization and sputtering and have not been properly considered in past studies as part of the overall cavity response and reestablishment. This effect may significantly alter cavity dynamics and power requirements