Wendelstein 7X 1

1
Wendelstein 7-X (1)
Basic parameters
Major radius
5.5 m Average plasma radius 0.53
m Magnetic field on axis 3.0
T Magnetic field on coils 5.8 T Number of field
periods 5 Average radius of coils
1.25 m Number of coils
50 Extra coils for variation
20 Magnetic energy
0.6 GJ Coil cross section Height
0.21 m Width
0.18 m Current density
48 MA/m2 Superconductor
NbTi
2
Wendelstein 7-X (2)
Rotational transform on axis
0.84 Rotational transform on boundary
0.99 Variation of iota
0.2 Variation of shear
0.1 Variation of
mirror field
0.1 Pfirsch-Schlüter currents ltjII2/jdia2gt
0.5 Magnetic well depth
0.01 MHD-stability limit ltßgtst
0.043 Equivalent
ripple
0.015 Ratio of bootstrap currents Ist/Itok
0.1
3
Wendelstein 7-X
Expected Results
Electron cyclotron heating 10 MW/140 GHz Neutral
beam heating 20 MW Ion cyclotron heating
Expected plasma parameters Density 31020
m-3 Temperature 10 keV Beta 4
4
Stellarator Reactor
The Helias reactor is an upgraded version of the
Wendelstein 7-X experiment under construction in
Greifswald. The dimensions of a Helias reactor
are determined by the following requirements -
There must be sufficient space for blanket and
shield - The magnetic field is small enough to
allow for NbTi-superconducting coils - Plasma
confinement must be sufficiently good to provide
ignition. The power balance is determined by a)
alpha-particle confinement, b) neoclassical
transport, c) anomalous transport.

• Inherent steady state operation
• One set of modular coils
• Zero toroidal current
• Optimized magnetic field
• Small neoclassical transport
• Zero bootstrap current
• Low averaged neutron
• wall load

5
Stellarator Reactor
Cryostat
Coils
Magnetic surface
6
Stellarator ReactorCoils

• Major Radius 22 m
• Av. Plasma Radius 1.85 m
• First wall 2600 m2
• Plasma Volume 1400 m3
• Magnetic Field 5 T
• Max. Magnetic Field 10 T
• Rotational Transform 0.87 - 0.98
• Number of Coils 50
• Magnetic Energy 100 GJ

SC Cable NbTi (FZK)
Number of turns 288 Length of turn 34.5 m Number
of layers 16 Winding current 37.5 kA SC
cable NbTi Cross section 32x32 mm2 Cooling
temperature 1.8 K Maximum field on coil 10
T Total length of cable 500 km
Coil crossection
7
Stellarator ReactorBlanket
Porthole
Blanket
Vacuum vessel
Ceramic breeder , Helium cooling Breeder
Li4SiO4 Multiplier Beryllium Extrapolation from
DEMO blanket (KfK 5429)
8
Helias Reactor Balance of plant
Power Flow Diagram
Fusion Power 3000 MW Alpha-heating Power 600
MW Neutron Power 2400 MW Mult. Factor 1.36 Nuclear
Power 3864 MW Recirculated Power 100
MW Thermal Power 3964 MW Efficiency of Convertor
0.35 Electric Power 1384 MW Power Output 1284 MW
Fuel Cycle
T/D-Atoms in Plasma 9.4x1022 Neutron
Rate 1.1x1021 s-1 Tritium Burn-up 470
g/day Deuterium Burn-up 313 g/day Particle Conf.
Time 7.5 s Tritium Flux 1.25x1022 s-1 (5355
g/day) Deuterium Flux 1.25x1022 s-1 (3566 g/day)
FZK