Researchers experimented with wire arrays imploding onto cylinders made of plastic foam, with two-dimensional computer simulation support from Los Alamos National Laboratory. This is the next challenge faced by all Z researchers. In collaborative experiments among Lawrence Livermore and Sandia scientists, led by Arthur Toor of Lawrence Livermore, foam layers surrounding a beryllium tube are used inside the wire array, thereby providing a slower, more precise collapse of the imploding plasma. In both the Sandia and Lawrence Livermore dynamic hohlraums, there were serious problems with integrity of the central region due to instabilities, but recent results show promise in controlling these instabilities. Nested wire arrays achieve 290 TW To achieve a radiated power of about 290 terawatts, Sandia researchers with Los Alamos researcher Darrell Peterson designed a nested wire array, which consists of two concentric wire arrays.
Incoming power vaporizes the outer wire array.
Its magnetic field drives the vaporized ring of wire material inward until the faster moving portions strike the inner wire array and are slowed. The deceleration allows the slower moving material at the back of the outer ring to catch up and, together, sweep up the material in the inner array and drive it forward. This reduces instabilities in the implosion. The vaporized materials then slam into each other at the central axis, converting the energy of motion into radiation energy with a much shorter pulse than if a single wire array had been used. Theory for the nested wire array experiment was worked out more than 10 years ago inside and outside the U.S. Experiments on Z with nested wire arrays began in October.