Patent Number: 
Section: claims

1. A hohlraum for an indirect drive inertial confinement fusion power plant in which the hohlraum surrounds a capsule at a central location containing fusion fuel, with the hohlraum comprising:an exterior surface having two end regions and a mid-region between the two end regions, the mid-region having a generally symmetrical cylindrical configuration of first diameter about a central axis and characterized by a center plane perpendicular to the central axis of the hohlraum and disposed at the central location, each of the end regions tapering from the first diameter to a second smaller diameter at ends of the hohlraum;a laser beam entrance hole at each of the end regions of the hohlraum;a covering at each of the end regions of the hohlraum to enclose a gas therein; anda hollow interior defined by an interior wall having a continuously curved oval shape, wherein normals to the interior wall are only perpendicular to the central axis of the hohlraum in the center plane. 2. A hohlraum as in claim 1 wherein each of the end regions comprises a truncated cone shaped protrusion extending between the mid-region and the laser beam entrance holes. 3. A hohlraum as in claim 2 wherein the covering over each of the laser entrance holes is substantially transparent. 4. A hohlraum as in claim 2 wherein the hollow interior contains an inert gas confined between the covering at each end of the hohlraum. 5. A hohlraum as in claim 4 wherein the inert gas comprises helium. 6. A hohlraum as in claim 1 further comprising a lining material disposed on the interior wall. 7. A hohlraum as in claim 6 wherein the lining material comprises a material of higher density than the interior wall. 8. A hohlraum as in claim 6 further comprising two infrared reflectors, one disposed between the covering at one end of the hohlraum and a mid-point along the central axis of the hohlraum and the other disposed between the covering at an opposite end of the hohlraum and the mid-point along the central axis of the hohlraum. 9. A hohlraum as in claim 8 further comprising a shield disposed on each of the two infrared reflectors. 10. A hohlraum as in claim 9 wherein each of the shields comprises material which is the same as the lining material. 11. A hohlraum as in claim 9 wherein each of the shields comprises a reflective disk having a center aligned to the central axis of the hohlraum. 12. A hohlraum as in claim 1 further comprising a membrane disposed perpendicular to the central axis to support the capsule along the central axis near a central point along the central axis. 13. A hohlraum as in claim 12 wherein the membrane comprises a carbon-based material. 14. A hohlraum as in claim 13 wherein the carbon-based material comprises at least one of polyimide, graphene, graphene-reinforced polymer, diamond-like-carbon, or diamond. 15. A hohlraum as in claim 1 further comprising a membrane disposed along the central axis to support the capsule along the central axis. 16. A hohlraum as in claim 6 wherein the lining material comprises a high-Z material such as lead. 17. A hohlraum as in claim 1 wherein the covering at each of the end regions comprises a carbon-based material. 18. A hohlraum as in claim 17 wherein the carbon-based material comprises at least one of polyimide, graphene, graphene-reinforced polymer, diamond-like-carbon, or diamond. 19. A hohlraum as in claim 1 wherein the tapering of the end regions comprises a linear taper from the first diameter to the second smaller diameter. 20. A hohlraum as in claim 2 wherein the truncated cone shaped protrusions are characterized by the first diameter near the mid-region and the second smaller diameter near the laser beam entrance holes.