Introduction – the Wendelstein 7-X stellarator

Wendelstein is to demonstrate the suitability of fusion devices of the stellarator type for a power plant


Objectives

The magnetic field cage of Wendelstein 7-X is to confine a plasma which, with temperatures of up to 100 million degrees and discharges lasting up to 30 minutes, will allow convincing conclusions on the suitability of stellarators for a power plant. Individual objectives will be to

  • investigate the good particle confinement of the optimised magnetic field and investigate the particle transport under reactor-like conditions
  • produce and heat the plasma with effective heating methods
  • develop methods of impurity control and investigate impurity transport
  • attain beta values (ratio of plasma pressure and magnetic field pressure) of 4 to 5 per cent and analyse the beta limit
  • demonstrate long-time or quasi-stationary operation
  • plasma replenishment, particle control, and plasma-wall interaction under continuous operation conditions


Achieving these objectives does not require producing an energy-yielding fusion plasma. This is because the properties of an ignited plasma can largely be transferred by the ITER tokamak to stellarators. Wendelstein 7-X can therefore dispense with the use of the radioactive fusion fuel, tritium, thereby greatly reducing costs.

 Technical data:

 Major plasma radius

5.5 metres
 Minor plasma radius 0.53 metre
 Magnetic field 3 tesla
 Pulse length
max. 30 minutes
 Plasma heating 14 megawatts
 Plasma volume 30 cubic metres
 Plasma mass 5 - 30 milligrams
 Plasma mixture Hydrogen, Deuterium
 Plasma temperature 60 - 130 million degrees
 Plasma density 3 x 1020 particles/cubic metre
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