| Popis: |
Geometrical arrangements for locating the large number of beamlets used in high-energy laser fusion facilities around a target chamber, suitable for the 1- to 2-MJ Phebus upgrade facility, are compared. The beamlets are clustered together and enter the target chamber area from two opposite poles. Beamlets from two different amplifier regions are interlaced around four pairs of conical surfaces, so that more symmetrical illumination of indirect drive targets is possible even when only some of the amplifiers are operational. A passive system is proposed to protect the focus lenses from X rays, ion debris, and internal target chamber pollutants. The system includes sacrificial debris shields and a static, [approximately] 2-m length of incondensable gas. A crosswise orientation allows for maximum operational flexibility; an in-line orientation uses three fewer mirrors per beamlet but requires a larger target chamber room and longer laser bays. Neutron protection includes concrete shielding and also an [approximately] 1- to 2-m-thick water shield positioned just inside the periphery of the target chamber room. Selected low-activation materials are used as much as possible inside the water shield to minimize the recovery time after a shot. 7 refs., 2 figs. |
