The X-ray intensity around the capsule must be very symmetrical to avoid hydrodynamic instabilities during compression. Earlier designs had radiators at the ends of the hohlraum, but it proved difficult to maintain adequate X-ray symmetry with this geometry. By the end of the 1990s, target physicists developed a new family of designs in which the ion beams are absorbed in the hohlraum walls, so that X-rays are radiated from a large fraction of the solid angle surrounding the capsule. With a judicious choice of absorbing materials, this arrangement, referred to as a "distributed-radiator" target, gives better X-ray symmetry and target gain in simulations than earlier designs.