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AN ARTIST'S RENDERING of a Sandia z-pinch in operation. (A gas puff is demonstrated instead of wires.) A cylindrically symmetrical annulus is prepared with current to flow in the vertical (Z) direction. The implosion shows the resultant plasma shrinking and getting hotter. The plasma becomes very, very hot as it stagnates on the cylindrical axis of symmetry, releasing energy outward in the form of X-rays.
The request was made after Sandia's continually improving Z accelerator - the most energetic and powerful laboratory producer of X-rays on Earth - achieved 1.8 million degrees Kelvin, passing the fourth and final milestone of 1.7 million degrees established by Sandia scientific researchers beginning four years ago and reviewed by scientific committees over the last two years.
In February Z had met three of its four milestones, and the fourth was near (Lab News, Feb. 27). The fourth has now been achieved.
Z would serve as a model for the larger X-1 machine. X-1 should produce X-ray temperatures of more than 3 million degrees, which, when combined with enough X-ray energy and power, should be sufficient to implode fusion capsules of deuterium and tritium (isotopes of hydrogen) to achieve high-yield fusion.
High-yield means that considerably more energy is released by a nuclear reaction than was used to ignite it. The reaction, the same type as occurs in the sun, could eventually be used to produce virtually limitless electrical power. The achievement also means that basic science experiments involving fusion capsules can begin on Z, as well as more intensive weapons physics experiments.
The basis for a series of technical breakthroughs initially involved adding more wires to a target the size of a spool of thread. Later, the size of this "wire array" was reduced, and multiple shells of wires increased the temperature even further.
Last summer the resulting progress on Z was characterized by VP Gerry Yonas (9000) as "astounding" and by a Cornell University scientist as "spectacular" (Lab News, Aug. 1, 1997). The levels of energy, power, and temperature have gone up since then.
The combination of several individual techniques for improving the uniformity of the X-ray source has resulted in the performance milestones being dramatically exceeded.
Specific milestones and achievements are:
The team of researchers, including scientists from Sandia, Los Alamos
National Laboratory, and Lawrence Livermore National Laboratory, hope that
a DOE meeting to decide on proceeding with conceptual design of X-1 can
be held in August.