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, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

's second largest

fusion Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole. Fusion may also refer to: Science and technology Physics *Nuclear fusion, multiple atomic nuclei combining to form one or more different atomic nucl ...

experiment after stellarator

Wendelstein 7-X The Wendelstein 7-X (abbreviated W7-X) reactor is an experimental stellarator built in Greifswald, Germany, by the Max Planck Institute for Plasma Physics (IPP), and completed in October 2015.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 In nuclear fusion power research, the plasma-facing material (or materials) (PFM) is any material used to construct the plasma-facing components (PFC), those components exposed to the plasma within which nuclear fusion occurs, and particularly t ...

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 depen ...

(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 isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one ...

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 of ...

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 Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...

. 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 ton The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...

s, a maximum magnetic field strength of 3.1 tesla, a maximum plasma current of 1.6 megaampere and maximum heating power of up to 27

megawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...

. Plasma heating and current drive in the ASDEX Upgrade is derived from several sources, namely 1 MW of

ohmic heating Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor produces heat. Joule's first law (also just Joule's law), also known in countries of former US ...

, 20 MW of neutral beam injection, 6 MW via

ion cyclotron resonance Ion cyclotron resonance is a phenomenon related to the movement of ions in a magnetic field. It is used for accelerating ions in a cyclotron, and for measuring the masses of an ionized analyte in mass spectrometry, particularly with Fourier transfo ...

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 m ...

heating (ECRH) at 140

gigahertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

. 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 was discovered in ASDEX in 1982.

External links

ASDEX Upgrade homepage

ASDEX Upgrade technical specs

References

{{Authority control Tokamaks

ASDEX

See also

External links

References