The B-dot probe diagnostic suite on the ASDEX Upgrade tokamak has recently been upgraded with a new 125 MHz, 14 bit resolution digitizer to study ion cyclotron emission (ICE). While classic edge emission from the low field side plasma is often observed, we also measure waves originating from the core with fast fusion protons or beam injected deuterons being a possible emission driver. Comparing the measured frequency values with ion cyclotron harmonics present in the plasma places the origin of this emission on the magnetic axis, with the fundamental hydrogen/second deuterium cyclotron harmonic matching the observed values. The actual values range from ∼27 MHz at the on-axis toroidal field BT = −1.79 T to ∼40 MHz at BT = −2.62 T. When the magnetic axis position evolves during this emission, the measured frequency values track the changes in the estimated on-axis cyclotron frequency values. Core ICE is usually a transient event lasting ∼100 ms during the neutral beam startup phase. However, in some cases, core emission occurs in steady-state plasmas and lasts for longer than 1 s. These observations suggest an attractive possibility of using a non-perturbing ICE-based diagnostic to passively monitor fusion alpha particles at the location of their birth in the plasma core, in deuterium-tritium burning devices such as ITER and DEMO.

1.
K. G.
McClements
 et al.,
Nucl. Fusion
55
,
043013
(
2015
).
2.
R.
D’Inca
,
M.
Garcia-Munoz
,
G.
Tardini
,
J.-M.
Noterdaeme
, and
ASDEX Upgrade Team
, in
Proceedings of the 38th EPS Conference on Plasma Physics
,
2011
.
3.
G. A.
Cottrell
 et al.,
Nucl. Fusion
33
,
1365
(
1993
).
4.
K. G.
McClements
,
R. O.
Dendy
,
C. N.
Lashmore-Davies
,
G. A.
Cottrell
,
S.
Cauffman
, and
R.
Majeski
,
Phys. Plasmas
3
,
543
(
1996
).
5.
W. W.
Heidbrink
 et al.,
Plasma Phys. Controlled Fusion
53
,
085028
(
2011
).
6.
S. G.
Thatipamula
,
G. S.
Yun
,
J.
Leem
,
H. K.
Park
,
K. W.
Kim
,
T.
Akiyama
, and
S. G.
Lee
,
Plasma Phys. Controlled Fusion
58
,
065003
(
2016
).
7.
M.
Ichimura
 et al.,
Nucl. Fusion
48
,
035012
(
2008
).
8.
K.
Saito
 et al.,
Plasma Sci. Technol.
15
,
209
(
2013
).
9.
R. O.
Dendy
,
C. N.
Lashmore-Davies
,
K. G.
McClements
, and
G. A.
Cottrell
,
Phys. Plasmas
1
,
1918
(
1994
).
10.
J. G.
Cordey
,
R. J.
Goldston
, and
D. R.
Mikkelsen
,
Nucl. Fusion
21
,
581
(
1981
).
11.
R.
Ochoukov
,
V.
Bobkov
,
H.
Faugel
,
H.
Fünfgelder
,
J.-M.
Noterdaeme
, and
ASDEX Upgrade Team
,
Rev. Sci. Instrum.
86
,
115112
(
2015
).
12.
R.
Ochoukov
 et al.,
EPJ Web Conf.
157
,
03038
(
2017
).
13.
L. G.
Askinazi
,
A. A.
Belokurov
,
D. B.
Gin
,
V. A.
Kornev
,
S. V.
Lebedev
,
A. E.
Shevelev
,
A. S.
Tukachinsky
, and
N. A.
Zhubr
,
Nucl. Fusion
58
,
082003
(
2018
).
14.
R. O.
Dendy
,
C. N.
Lashmore-Davies
, and
K. F.
Kam
,
Phys. Fluids B
4
,
12
(
1992
).
15.
B.
Chapman
,
R. O.
Dendy
,
K. G.
McClements
,
S. C.
Chapman
,
G. S.
Yun
,
S. G.
Thatipamula
, and
M. H.
Kim
,
Nucl. Fusion
57
,
124004
(
2017
).
16.
L.
Carbajal
,
R. O.
Dendy
,
S. C.
Chapman
, and
J. W. S.
Cook
,
Phys. Plasmas
21
,
012106
(
2014
).
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