PRODUCING HEAT AS HOT AS THE SUN
Sandia machine helps study of cosmos, energy, nuke tests
Sandia researchers can generate over 4 million degrees Fahrenheit for experimentation.
There is a small part of Albuquerque where, on a day last week, the temperature soared as hot as the inside of the sun. That’s not an exaggeration. For one brief moment — for about three to five billionths of a second — a small spot in a Sandia National Laboratories facility reached about 4.2 million degrees Fahrenheit. And that is by design.
The Z-machine, which has been in operation in one form or another since 1985, is designed to produce a temperature that is equal to the temperature at a spot below the sun’s surface, researcher Taisuke Nagayama said. And it was used in a test last week.
The device, which from above resembles a mechanical wagon wheel with 36 spokes, is contributing to research on several different fronts, Sandia spokesman Neal Singer said.
There is the research being done by astrophysicists like Nagayama, who are using the device to study the composition of the sun, other stars and black holes, as well as exoplanets, planets that orbit stars outside the solar system.
“It helps you understand
the universe and how it was created,” he said.
The Z-machine is also being used in experiments that provide data for scientists involved in the development of nuclear weapons.
“We receive major funding for tests that create conditions for nuclear fusion that would happen in nuclear weapons,” Singer said. The information the tests provide was once obtainable only through above-and below-ground explosions of nuclear devices.
Once the data is downloaded into a super computer, researchers are getting the same results without endangering human life or the environment.
Tests are also being conducted with the device that are being used in the development of nuclear fusion energy — think “Star Trek” technology for transportation — although the fruit of that labor is still years away. It is also being used for material science research.
The Z-machine is currently being used to help resolve discrepancies with an astronomical model used for 40 years to predict the sun’s behavior, as well as the life and death of stars. The discrepancies involve the makeup of the sun, which is composed of hydrogen, helium and smaller amounts of other elements, and the amount of opacity — the level in which energy escapes the sun core.
“By observing real-world discrepancies between theory and our experiments at Z, we were able to identify weaknesses in opacity figures inserted into solar models,” said Nagayama, lead author on the Sandia groups’ latest publication in Physical Review Letters.
Researchers such as Nagayama use the Z-machine to test heavier elements that are found in the sun, such as iron, to get an idea of their makeup and their effect on opacity. Chromium and nickel, which are smaller and larger than iron, have been tested because they are adjacent to iron in the periodic table — as though iron were being tested closer and farther from the sun’s core.
The materials being tested are placed in the target area of the device. Sandia’s Z-machine uses electricity to create radiation and high magnetic pressure.
When the accelerator fires, powerful electrical pulses strike a target at the center of the machine. Each shot from Z carries more than 1,000 times the electricity of a lightning bolt and is 20,000 times faster. The target is about the size of a spool of thread and it consists of hundreds of tungsten wires, each thinner than a human hair, enclosed in a small metal container known as a hohlraum (German for hollow space). The hohlraum serves to maintain a uniform temperature.
The flow of energy through the tungsten wires dissolves them into plasma and creates a strong magnetic field that forces the exploded particles inward.
When Z fires, the extreme heat changes solids such as iron into plasma as it exists in the sun, but only for nanoseconds.
“Our work over the last five years has been focused on resolving the discrepancies,” Nagayama said. “And yet the new results mean new science may be necessary to account for them.”