We also present an assessment of the impact of dust on ITER plasma performance
and discuss the gaps in our understanding of dust physics in magnetic fusion devices.
5.1 Experimental Study of Dust in Magnetic Fusion Devices
5.1.1 Dust Particle Density, Size Distribution,
and Composition in Fusion Devices
The size of the dust particles found in fusion devices is ranging from nano-meters
(e.g. see Fig. 5.4) to few hundred μm in the Alcator C-Mod tokamak [16]. Usually,
1640 1641 1642 1643 1644 1645
Time (s)
T e (ECE:R=3.466m)
P ref (3.5U)
Shot 53775
Spark
Power
[kW]
n
e
[10 19
m –3
]
T
e
[keV]
FeX
P fwd (3.5U)
CIII
CIII, FeX
[a.u.]
0
20
40
60
80
0
2
4
6
8
0
0.5
1
0
0.5
1
0
50
100
150
200
250
1.5
P
rad
[a.u.]
Fig. 5.1 Spontaneous ejection (“spark”) of dust particles from the first wall terminates a long pulse
discharge in the LHD stellarator. The “spark” event observed with CCD camera (left) and time
evolution of the plasma parameters (right). (Reproduced with permission from [6], © Elseiver 2007)
Fig. 5.2 Dust observed by a fast camera in the DIII-D tokamak in front of the neutral beam
injection (NBI) port 1 ms before (a), during (b) and 2 ms after (c) an NBI pulse. (Reproduced with
permission from [12], © IAEA 2009)
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5 Dust in Fusion Plasmas