A Carbon-Carpet First Wall for the Laboratory Microfusion Facility

A first wall concept for the Laboratory Microfusion Facility (LMF) that uses carbon fibers in a brush- or carpet-like configuration is described. This material and geometric configuration provide an extremely effective way of absorbing the intense burst of soft x-ray radiation from the fusion energy pulse without damaging the underlying structure. The 2-cm-long carbon fibers are pointed at the target so that the x-rays illuminate the sides of the fibers at a glancing angle. The authors describe how the carpet-like configuration reduces the impulse due to the blow-off of material vaporized by the x-rays. Resulting stresses in the support structure are now low enough for the chamber radius to be brought in to 3 m, which is much smaller than a chamber with an unprotected first wall. The authors conclude that this is a viable and attractive concept for the LMF first wall.