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 confines a plasma which, with temperatures of up to 100 million degrees and discharges lasting up to 30 minutes, shall 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
- conduct divertor studies
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 |