The Scientific Impact of Z
The Z machine is the Earth’s most powerful and efficient laboratory radiation source.
To scientists, this means that in each of the approximately 200 shots Z fires every year, the machine uses currents of about 26 million amps to reach peak X-ray emissions of 350 terawatts and an X-ray output of 2.7 megajoules. To everyone else, however, these numbers simply mean that the Z machine can create conditions found nowhere else on Earth. The implications, of course, are huge.The Z machine is located in Albuquerque, N.M., and is part of the Pulsed Power Program, which started at Sandia National Laboratories back in the 1960s. Pulsed power is a technology that concentrates electrical energy and turns it into short pulses of enormous power, which are then used to generate X-rays and gamma rays. Produced in the laboratory, this controlled radiation creates conditions similar to those caused by the detonation of nuclear weapons, which is why from its earliest days pulsed power has been used to study weapons effects.
For decades pulsed power has been explored with machines, relatively small at first, now in some cases more than three times the area of a tennis court, called accelerators. As accelerators were being developed for use in weapons research, a different kind of technology, the laser, was also being perfected and used for similar purposes.
In addition to weapons research, however, for many years lasers were seen as the frontrunner technology in another area, an area in which accelerators did not fare as well. That area was fusion research. Fusion, the process by which two atomic nuclei are joined together, is a powerful reaction long used in the development of weapons and currently being explored as a potential source of energy.
Lasers have been useful in fusion research because of their great ability to focus tightly on a small area. This is crucial to fusion experiments because in order to compress and heat the starting materials enough to fuse atoms, power must be concentrated sharply on the target.
In comparison to laser beams, the particle beams produced by early accelerators were difficult to focus to a small area. But during the 1980s Sandia developed complex accelerators designed specifically to study controlled fusion, and within the Pulsed Power Program, simulation of weapons effects started to vie with fusion in importance.
It didn’t take long for one of Sandia’s accelerators to start making big progress in the realm of fusion – but it was not with particle beams, but with another technology known as the Z pinch. The Z pinch had been studied at Sandia since the 1960s as part of the weapons program, but its potential for fusion had not been explored because particle beams seemed better suited for that purpose.
In light of the Z-pinch revelation, however, Sandia decided to shift the focus of its fusion research away from particle beams, and in 1997 it reconfigured one of its accelerators to explore the potential of Z pinches instead. Accelerators, in particular the one that came to be known as the “Z machine,” suddenly became an unexpected and very strong contender in the fusion arena.
For the past decade, images of the spectacular Z machine in action have garnered as much attention in the popular press as its scientific breakthroughs have among researchers. In 2004 the National Nuclear Security Administration authorized funding to refurbish and upgrade Z into the more powerful ZR. The refurbishment, completed in 2007, delivered improvements on every front, and today the facility continues to be a major tool in the development of Sandia’s weapons effects, weapons physics, and fusion technologies, all of which make invaluable contributions to science, national security and fusion energy research.
