Sandia formally proposes to design accelerator expected to produce high-yield fusion

ALBUQUERQUE, N.M. — Permission to prepare a conceptual design for an accelerator, X-1, has been formally requested by Sandia National Laboratories President Paul Robinson in a letter to the Department of Energy (DOE).

If funded, X-1 would be expected to reach initial operating capability by about 2007 and high-yield fusion by about 2010 as well as provide important data for the nation’s stockpile stewardship program.

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 four years ago, and reviewed by scientific committees during the last two years.

In February, Z had met three of its four milestones, and the fourth was near. 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 our 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. 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:

• Energy, 1.5 megajoules; achieved, 2.0 megajoules.
• Power, 150 terawatts; achieved, 290 terawatts.
• Temperature: weapons physics configurations, 100 eV (1.2 million degrees Kelvin); achieved, 140 eV (1.6 million degrees K).
• Temperature in a configuration suitable for target compression (fusion) experiments, 150 eV (1.7 million degrees K); achieved, 155 eV (1.8 million degrees K).

The team of researchers, including scientists from Sandia, Los Alamos, and Livermore national laboratories, hope that a DOE meeting to decide on proceeding with conceptual design of X-1 can be held in August.

For more information:

• Z, which reaches temperatures of the Sun, to help astronomers interpret Chandra data (November 5, 1999)
• Concept for rapid-fire thermonuclear explosions proposed by Sandia scientists (September 13, 1999)
• Sandia researchers push Z machine to new limits to test radiation effects (June 16, 1999)
• Sandia formally proposes to design accelerator expected to produce high-yield fusion (April 8, 1998)
• Another dramatic climb toward fusion conditions for Sandia Z accelerator (March 2, 1998)
• Output of Sandia Z Accelerator Climbs Closer to Fusion (August 1, 1997)
• High-Output Sandia Accelerator Able to Predict Nuclear Blast Physics (December 2, 1996)

Technical contacts:
Gerold Yonas, gyonas@sandia.gov, (505) 845-9819
Don Cook, dlcook@sandia.gov, (505) 845-7446