Thursday, March 09, 2006

Z machine exceeds two billion degrees Kelvin: hotter than the interiors of stars

Sandia’s Z machine has produced plasmas that exceed temperatures of 2 billion degrees Kelvin — hotter than the interiors of stars. The unexpectedly hot output, if its cause were understood and harnessed, could eventually mean that smaller, less costly nuclear fusion plants would produce the same amount of energy as larger plants.
...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.

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