A compact ECR ion source was used to investigate the effect that the shape of the plasma electrode (PE) has on the surface production of negative hydrogen (H) ions. A C12A7 electride PE produced ten times more H-ion current compared with a molybdenum (Mo) PE of the identical design. Four times more H- ion current was obtained when the ion source plasma faces the 45-degree tapered hole opened on the surface of the electride PE as compared to the current obtained from a plasma facing the flat side of the PE. This enhancement in H- ion current may indicate larger surface production of H ions by the enlarged surface area. A Mo PE also showed a similar effect but with less pronounced H- ion current enhancement. A beam trajectory study showed that the beam divergence was larger when the source plasma faced against the tapered side of the PE.

1.
M.
Bacal
and
M.
Wada
,
Appl. Phys. Rev.
,
2
,
0211305
(
2015
).
2.
M.
Bacal
, et al,
Rev. Sci. Instrum.
67
,
1138
(
1996
).
3.
G.S.
Fulcher
,
Phys. Zs.
Xiii
,
1137
(
1912
):
G.S.
Fulcher
,
Astrophys. Journal
xxxvii
,
60
(
1913
).
4.
Yu.
Belchenko
, et al,
Nuclear Fusion
,
14
(
1
),
113
114
(
1974
).
5.
M.
Wada
, et al.,
3rd Int. Symp. Production and Neutralization of Negative Ions and Beams
,
Upton, NY
,
AIP Conf. Proc. Ill
, p.
247
(
1983
).
6.
P.
Kumar
 et al,
J. Phys. D :Appl. Phys.
,
44
,
372002
(
2011
).
7.
A.
Ahmad
, et al,
J. Phys. D : Appl. Phys.
,
47
,
085201
(
2014
).
8.
M.
Sasao
,
K.
Tanemura
,
M.
Wada
, and
K.
Tsumori
,
AIP Conference Proceedings
1869
,
020005
(
2017
).
9.
Mamiko
Sasao
,
Roba
Moussaoui
,
Dmitry
Kogut
,
James
Ellis
,
Gilles
Cartry
,
Motoi
Wada
,
Katsuyoshi
Tsumori
, and
Hideo
Hosono
,
Applied Physics Express
11
,
066201
(
2018
).
10.
M.
Kobayashi
,
M.
Sasao
,
M.
Kisaki
,
T.
Eguchi
, and
M.
Wada
,
AIP Conference Proceedings
2052
,
020003
(
2018
).
11.
12.
T.
Eguchi
 et al.,
Rev. Sci. Instrum.
91
,
013508
(
2020
).
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