power x-rays on nuclear missiles' warheads. The space inside the wire array was filled with polystyrene, which helps homogenize the X-ray flux. Any country developing thermonuclear weapons has its own Z machine, but those not using water lines had long rising pulses (for example 800ns in the Sphinx, the French machine at Gramat). In the UK, the Magpie machine was situated at the Imperial College under control of Malcolm Haines. By removing the polystyrene core, Sandia was able to obtain a thin 1.5 mm plasma cord in which 10 million amperes flowed with 90 megabars of pressure. Early operation 1996–2006 The key attributes of Sandia's Z machine are its 18 million amperes and a discharge time of less than 100 nanoseconds. The array of tungsten wires is called a "liner". In 1999, Sandia tested the idea of nested wire arrays; the second array, out of phase with the first, compensates for Rayleigh-Taylor instabilities. In 2001, Sandia introduced the Z-Beamlet laser (from surplus equipment of the National Ignition Facility) as a tool to better image the compressing pellet. This confirmed the shaping uniformity of pellets compressed by the Z machine. Sandia announced the fusing of small amounts of deuterium in the Z machine on April 7, 2003. Besides being used as an X-ray generator, the Z machine propelled small plates at 34 kilometers a second, faster than the 30 kilometers per second that Earth travels in its orbit around the Sun, and four times Earth's escape velocity (3 times it at sea level). It also successfully created a special, hyperdense "hot ice" known as ice VII, by quickly compressing water to pressures of 70,000 to 120,000 atmospheres (7 to 12 GPa). Mechanical shock from impacting Z-machine accelerated projectiles is able to melt diamonds. A good overview of the different missions of the Z machine can be found in the 2002 Trivelpiece committee report which reviewed the pulsed power activities at Sandia. During this period the power of X-ray produced jumps from 10 to 300TW. In order to target the next milestone of fusion breakeven, another upgrade was then necessary Prospects A $60 million (raised to $90 million) retrofit program called ZR (Z Refurbished) was announced in 2004 to increase its power by 50%. The Z machine was dismantled in July 2006 for this upgrade, including the installation of newly designed hardware and components and more powerful Marx generators. The de-ionized water