Magnetic Fields and Magnetic Diagnostics for Tokamak Plasmas

Magnetic fields and tokamak plasmas
Alan Wootton
Figure 18.5. Current density profiles for TNT
Given the current density we can also attempt to deduce the safety factor q.
Internal magnetic measurements are also used to determine the internal electric field. From
Faraday's law
∫
l
E • dl = − d ⎛
⎜
dt ⎝
∫
S
⎞
B •ndS⎟ 18.8
⎠
we have, applying this to the geometry of Figure 18.6,
a
E φ
( r) = E φ
( a) − ∫ d B
dt
θ
dr 18.9
r
-E θ
- E φ
E
φ
Figure 18.6. The geometry used to describe the
measurements of internal electric field
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