Z machine
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The Z machine is a test facility for carrying out material tests under very high temperatures and extreme pressure conditions. It is in the Sandia National Laboratories (SNL) in Albuquerque / New Mexico / USA . It should also contribute to the development of a nuclear fusion power plant . In 2005 it was also the most powerful artificial X-ray source .
The name Z-machine is derived
- from the vertical exit direction of the X-rays (see also Z-axis )
- from the vertical wires (see below)
The Z-machine is an example of a Z-pinch ( ie, Z-squeeze ) arrangement for nuclear fusion.
The lead scientist is Thomas WL Sanford .
construction
The Z-machine is a cylinder with a diameter of 32 m and a height of 6 m, surrounded by 36 radially arranged electrical conductors with a diameter of over 1 m. In the middle of the vessel, which is filled with deionized water for insulation , there is a vacuum chamber with a diameter of 3 m. This contains the so-called “ Z-pinch ”, a cylindrical arrangement of 300 parallel tungsten wires running in the Z direction, the size of a spool of thread (approx. 20 cm high). The tungsten wires have a diameter of 10 µm, about 1/7 the thickness of a human hair. In the center of this wire cylinder sits the fusion capsule, a peppercorn-sized plastic ball filled with a mixture of deuterium and tritium . In order for the atomic nuclei to fuse, the capsules have to be compressed to a fraction of their original size and extremely heated. This can be achieved through the radiation pressure of a very intense X-ray radiation.
To generate this X-ray radiation, an electrical current of up to 20 million amperes is sent through all 36 radial conductors at exactly the same time for a very short time of less than 100 nanoseconds . The fine tungsten wires in the center evaporate suddenly and transform into an extremely hot, ionized gas - a plasma . The current flow then generates a strong magnetic field in the (electrically conductive) plasma, which is strongly compressed and heated radially to the vertical axis (so-called pinch effect ). As a result, the plasma in turn heats the wall material of the surrounding cylinder to a temperature of up to a few billion Kelvin . As a result, this cylinder emits an intense X-ray pulse for a brief moment, with a peak power of 290 TW . If this X-ray pulse hits the fusion capsule, the radiation pressure compresses it to a fraction of its original size and heats it up considerably. For a few nanoseconds, around 80 times the instantaneous power is used that is consumed all over the world.
The electrical energy is provided by Marx generators .
business
In 2003, the scientists succeeded in compressing the fusion capsule to one sixth of its original diameter using an X-ray pulse of 120 TW. The density of the deuterium nuclei increased two hundred times. Under these conditions, two nuclei of the heavy and super-heavy hydrogen isotopes deuterium and tritium are brought so close together that they fuse to form a helium nucleus . The researchers estimate that their fusion released an energy of around 4 mJ .
In 2006 it was announced that a plasma with a temperature of over 2 billion Kelvin could be generated, a temperature that is higher than that inside stars (in the core of the sun , for example, only about 15 million Kelvin are reached). In addition, the energy of the X-ray radiation emitted was four times as great as would have been expected with the amount of kinetic energy supplied. These results have so far been confirmed experimentally several times over a period of 14 months, but have not yet been fully explained.
The expansion to a larger " ZR machine " is being planned. The aim is to use it to generate X-ray pulses of up to 350 TW, higher densities and temperatures, and thus also to release significantly larger amounts of energy.
Individual evidence
- ↑ Sandia's Z machine Exceeds two trillion degrees Kelvin. Retrieved May 7, 2010 .