ASDEX Upgrade (''Axially Symmetric Divertor Experiment'') is a divertor

tokamak A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being ...

, that went into operation at the Max-Planck-Institut für Plasmaphysik, Garching in 1991. At present, it is

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

's second largest fusion experiment after stellarator Wendelstein 7-X.

Overview

To make experiments under reactor-like conditions possible, essential plasma properties, particularly the plasma density and pressure and the wall load, have been adapted in ASDEX Upgrade to the conditions that will be present in a future fusion power plant. ASDEX Upgrade is, compared to other international tokamaks, a midsize tokamak experiment. It began operation in 1991 and it succeeds the ASDEX experiment, which was in operation from 1980 until 1990. One innovative feature of the ASDEX Upgrade experiment is its all-

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...

first wall; tungsten is a good choice for the first wall of a tokamak because of its very high

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

(over 3000 degrees Celsius) which enables it to stand up to the very high heat fluxes emanating from the hot plasma at the heart of the tokamak; however there are also problems associated with a tungsten first wall, such as tungsten's tendency to ionise at high temperatures, "polluting" the plasma and diluting the

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus ...

fuel mix. Furthermore, as a high ''Z'' material, radiation from fully ionized tungsten in the plasma is several orders of magnitude higher than that of other proposed first wall components such as carbon fibre composites (CFCs) or beryllium. This result allows for far less tungsten to "contaminate" a proposed break-even plasma. ASDEX Upgrade will examine ways to overcome this problem, in preparation for the construction of ITER's first wall. The experiment has an overall radius of 5 metres, a gross weight of 800 metric tons, a maximum magnetic field strength of 3.1 tesla, a maximum plasma current of 1.6

megaampere The ampere (, ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to elect ...

and maximum heating power of up to 27 megawatt. Plasma heating and current drive in the ASDEX Upgrade is derived from several sources, namely 1 MW of ohmic heating, 20 MW of neutral beam injection, 6 MW via ion cyclotron resonance heating (ICRH) at frequencies between 30 and 120 megahertz, and 2 x 2 MW of

electron cyclotron resonance Electron cyclotron resonance (ECR) is a phenomenon observed in plasma physics, condensed matter physics, and accelerator physics. It happens when the frequency of incident radiation coincides with the natural frequency of rotation of electrons in ...

heating (ECRH) at 140 gigahertz. It has 16 toroidal field coils and 12 poloidal field coils. Three large flywheel generators feed the 580 MVA pulsed power supply system for the magnetic confinement and plasma heating.

ASDEX

ASDEX (with a major radius R=1.65m, minor radius a=0.4m, and plasma current Ip≤500kA) started operation in 1980. In 1991, it was dismantled by personnel of the Southwestern Institute of Physics (SWIP), transported to Chengdu, China, and its main components were used to build the HL-2A. The

H-mode High-confinement mode, or H-mode, is an operating mode possible in toroidal magnetic confinement fusion devices mostly tokamaks, but also in stellarators.List of fusion experiments * Edge-localized mode * Ball-pen probe

External links

ASDEX Upgrade homepage

ASDEX Upgrade technical specs

References

{{Authority control Tokamaks