Power plant
Tokamak
To construct the magnetic field cage a tokamak requires
three superposed magnetic fields: Firstly, a ring-shaped field produced
by plane external coils; secondly, the field of a current flowing in the
plasma. The field lines of the combined field are then helical. This is
what produces twisting of the field lines and formation of magnetic surfaces,
which are necessary for confining the plasma. A third, vertical field
fixes the position of the current in the plasma.
The plasma current is normally induced by a transformer coil. This is why a tokamak does not work in continuous, but in pulsed mode: In a transformer it is only for a limited time that an increasing current can be generated in the primary winding so that a current can be driven in the plasma. The transformer must, then be "discharged" and the current started up afresh. In order to achieve steady state operation in a future tokamak power plant, investigations are being conducted on methods of generating current in continuous mode, e.g. by means of high-frequency waves.
The plasma current is normally induced by a transformer coil. This is why a tokamak does not work in continuous, but in pulsed mode: In a transformer it is only for a limited time that an increasing current can be generated in the primary winding so that a current can be driven in the plasma. The transformer must, then be "discharged" and the current started up afresh. In order to achieve steady state operation in a future tokamak power plant, investigations are being conducted on methods of generating current in continuous mode, e.g. by means of high-frequency waves.
The magnetic system of a tokamak
[ Last Update 02.11.2009 | Responsible | Sitemap | IPP-Home | Disclaimer ]