A magnetic probe array is constructed to measure precisely the spatial structure of a small fluctuating field included in a strong confinement field that varies with time. To exclude the effect of the confinement field, the magnetic probes consisting of figure-eight-wound coils are prepared. The spatial structure of the fluctuating field is obtained from a Fourier analysis of the probe signal. It is found that the probe array is more sensitive to the fluctuating field with a high mode number than that with a low mode number. An experimental demonstration of the present method is attempted using a field-reversed configuration plasma, where the fluctuating field with 0.1% of the confinement field is successfully detected.

1.
S. V.
Mirnov
,
Plasma Phys. (J. Nucl. Energy, Part C)
7
,
325
(
1965
).
2.
G.
Saibene
 et al,
Nucl. Fusion
45
,
297
(
2005
).
3.
K.
Toi
 et al,
Phys. Plasmas
12
,
020701
(
2005
).
4.
M.
Nagata
 et al,
Phys. Rev. Lett.
90
,
225001
(
2003
).
5.
M.
Tuszewski
,
Nucl. Fusion
28
,
2003
(
1988
).
6.
J. T.
Slough
and
A. L.
Hoffman
,
Phys. Fluids B
5
,
4366
(
1993
).
7.
K.
Fujimoto
,
M.
Okada
,
H.
Gota
,
Y.
Hasegawa
,
T.
Fujino
,
T.
Asai
,
T.
Takahashi
, and
Y.
Nogi
,
Phys. Plasmas
12
,
102513
(
2005
).
8.
R. J. J.
Van Heijningen
,
D. J.
Maris
,
C.
Bobelduk
, and
P. C. T.
Van Der Laan
,
Plasma Phys.
14
,
205
(
1972
).
9.
H. Y.
Che
,
T. H.
Ivers
, and
M. E.
Mauel
,
Rev. Sci. Instrum.
59
,
1057
(
1988
).
10.
H.
Ohi
 et al,
Phys. Rev. Lett.
51
,
1042
(
1983
).
You do not currently have access to this content.