Researchers at Cornell University have created striking images of tiny
subjects, including houseflies and fruit flies, illuminated by the brilliant
burst of x rays emitted by vaporizing wires. The radiographs (x-ray
photographs) help to demonstrate the characteristics of the flash that
erupts as 100,000 amps of current are rammed through the crossed wires
of an "X-pinch" machine.
When a current courses through X-pinch wires, the metal vaporizes and
leaves trails of plasma behind. In the absence of solid wires, the current
continues to flow through the plasma, leading to a magnetic field that
in turn pinches down on the plasma. With increasing current, the magnetic
field grows and ultimately causes the plasma to implode, typically resulting
in one or two dense plasma points less than a thousandth of an inch
across with temperatures as high as 10 million K. The unstable plasma
points emit bursts of x-rays that last less than a billionth of a second,
and then the plasma points explode.
Bright, point-source x-ray bursts generated by the X-pinch machine
are ideal illumination for x-ray radiographs of thin objects. Details
on the order of a few millionths of a meter, such as the hairs on a
fly's wing, would be impossible to discern with larger x-ray sources,
but are clearly visible in images created with X-pinch flashes (see
Pikuz of Cornell will discuss X-pinch photography at the annual
meeting of the American Physical Society's Division of Plasma Physics
(Long Beach, California, Oct 29-Nov 2), while papers by T.
A. Shelkovenko and D.
B. Sinars will address detailed studies of the X-pinch plasma itself.
(For additional information, please visit the conference's Virtual
Pressroom; see a Cornell
press release; or contact David Hammer, email@example.com, 607-255-3916)