Sandia's Z Machine Heats Particles Past Star's Interior

A particle accelerator at Sandia National Laboratories has heated a swarm of charged particles to a record 2 billion degrees Kelvin (3.6 billion degrees Farenheight), a temperature beyond that of a star's interior.

Scientists working with Sandia's Z machine said the feat also revealed a new phenomenon that could eventually make future nuclear fusion power plants smaller and cheaper to operate than if the plants relied on previously known physics.

Sandia's experiment, which held up in tests and computer modeling in the 14 months since it was first done, was outlined in the Feb. 24 edition of Physical Review Letters. [link to article abstract]

The most recent advance resulted in an output X-ray power of about 290 trillion watts -- for billionths of a second, about 80 times the entire world's output of electricity.


Explanation of the experiment, and questions it has raised:

Z’s energies in these experiments raised several questions.

First, the radiated x-ray output was as much as four times the expected kinetic energy input.
Ordinarily, in non-nuclear reactions, output energies are less — not greater — than the total input energies. More energy had to be getting in to balance the books, but from where could it come?

Second, and more unusually, high ion temperatures were sustained after the plasma had stagnated — that is, after its ions had presumably lost motion and therefore energy and therefore heat — as though yet again some unknown agent was providing an additional energy source to the ions.

Sandia’s Z machine normally works like this: 20 million amps of electricity pass through a small core of vertical tungsten wires finer than human hairs. The core is about the size of a spool of thread. The wires dissolve instantly into a cloud of charged particles called a plasma.

The plasma, caught in the grip of the very strong magnetic field accompanying the electrical current, is compressed to the thickness of a pencil lead. This happens very rapidly, at a velocity that would fly a plane from New York to San Francisco in several seconds.

At that point, the ions and electrons have nowhere further to go. Like a speeding car hitting a brick wall, they stop suddenly, releasing energy in the form of X-rays that reach temperatures of several million degrees — the temperature of solar flares.

The new achievement — temperatures of billions of degrees — was obtained in part by substituting steel wires in cylindrical arrays 55 mm to 80 mm in diameter for the more typical tungsten wire arrays, approximately only 20 mm in diameter. The higher velocities achieved over these longer distances were part of the reason for the higher temperatures.

Haines theorized that the rapid conversion of magnetic energy to a very high ion plasma temperature was achieved by unexpected instabilities at the point of ordinary stagnation: that is, the point at which ions and electrons should have been unable to travel further. The plasma should have collapsed, its internal energy radiated away. But for approximately 10 nanoseconds, some unknown energy was still pushing back against the magnetic field.

Haines’ explanation theorizes that Z’s magnetic energies create microturbulences that increase the kinetic energies of ions caught in the field’s grip. Already hot, the extra jolt of kinetic energy then produces increased heat, as ions and their accompanying electrons release energy through friction-like viscous mixing even after they should have been exhausted.