Z machine
Encyclopedia : Z : ZM : ZMA : Z machine
- This article is about the X-ray generator. For the Infocom virtual machine, see Z-machine.
The Z machine is the largest X-ray generator in the world and is designed to test materials in conditions of extreme temperature and pressure. It is operated by Sandia National Laboratories to gather data to aid in computer modeling of nuclear weapons. The Z machine is located at Sandia's main site in Albuquerque, New Mexico.
Operation overview
The machine operates by releasing an electrical pulse and associated magnetic field. The energy from a 20-million-ampere electrical discharge vaporizes an array of thin tungsten wires and a powerful magnetic field crushes the ensuing plasma. The collapsing plasma produces X-rays which create a shock wave that bears on the material being tested. The powerful fluctuation in the magnetic field (or "electromagnetic pulse") also generates electric current in all of the metallic objects in the room (see picture at right).It gets its name because current travels vertically into the target, which is conventionally the z axis (x and y being horizontal, see Z-pinch).
Originally designed to supply 50 terawatts of power in one fast pulse, technological advances allowed this to increase to 290 terawatts, enough to study nuclear fusion. Z releases 80 times the world's electrical power usage for a few trillionths of a second. However, only a small amount of electricity is consumed for each test (equal to the usage of 100 houses for two minutes). Marx generators are slowly charged with energy prior to firing.
Sandia announced the fusing of deuterium in the Z machine on April 7, 2003. A 60 million dollar refurbishment program was announced in 2004 that will raise the power output to 350 terawatts. The X-ray output will be 2.7 megajoules.
The Z Machine is now able to propel small plates at 34 kilometers a second, faster than the 30 kilometers per second that Earth travels in its orbit around the Sun, and three times Earth's escape velocity.
In 2006, the Z Machine produced plasmas with temperatures in excess of 2 GK (109 K) or 3.6 billion oF. This temperature, corresponding to a 10 to 15% efficiency in converting electrical energy to soft x-rays, was much higher than anticipated. It is theorized that small-scale turbulence and viscous damping are converting magnetic energy into thermal energy of the ions, which then transfer their energy to the electrons through collisions.
The Sandia Z-IFE project
- Further information: Inertial fusion power plant
The figure represents a cutaway of a reactor as devised by Sandia, a production plant being made up of several such reactors (12 in the ZP-3 demonstration plant, from which 10 are working simultaneously). Using the analogy previously introduced, such a design is equivalent to the multiple cylinders of a gasoline engine.
Without going into technical details (readers wishing further informations will find them in the various links showed at the bottom of the article), it is possible to distinguish the following elements:
- the red triangular device ("cartridge") corresponds to the group formed by the fuel microcapsule, the "wires array" and the power transmission device; cartridges are transported to the top of the reactor chamber by an automatic supplying system, the rail which can be seen in the upper part of the image being a part of it;
- the thick horizontal blue line, tangent to the reaction chamber, is the power transmission line, intended to take to the "wires array" device the extremely short and powerful pulseFor further details, see Pulsed power article. necessary to the z-pinch process;
- the reactor chamber is filled by an inert gas (in order to avoid any undesirable chimical reaction) under low pressure (20 torr, the normal atmospheric pressure being 760 torr);
- the internal blanket of the reactor chamber is a thick-liquid wall of Flibe (liquid mixture of lithium fluoride and beryllium difluoride) intended to protect the external wall, to absorb the fusion neutron energy, and to produce tritiumTritium is produced when neutrons created during the fusion irradiates Flibe lithium.;
- the system intended to recycle the cartridges debris collected by the Flibe "pool", after their destruction at the time of the fusion.
Notes and references
See also
- Sandia National Laboratories
- Fusion power
- Stockpile stewardship
- Pulsed power
- Inertial fusion power plant
External links
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