We report the manipulation of positron orbits in a toroidal dipole magnetic field configuration realized with electric fields generated by segmented electrodes. When the toroidal circulation motion of positrons in the dipole field is coupled with time-varying electric fields generated by azimuthally segmented outer electrodes, positrons undergo oscillations of their radial positions. This enables quick manipulation of the spatial profiles of positrons in a dipole field trap by choosing appropriate frequency, amplitude, phase, and gating time of the electric fields. According to numerical orbit analysis, we applied these electric fields to positrons injected from the NEPOMUC slow positron facility into a prototype dipole field trap experiment with a permanent magnet. Measurements with annihilation γ-rays clearly demonstrated the efficient compression effects of positrons into the strong magnetic field region of the dipole field configuration. This positron manipulation technique can be used as one of essential tools for future experiments on the formation of electron-positron plasmas.

1.
V.
Tsytovich
and
C. B.
Wharton
,
Comments Plasma Phys. Control. Fusion
4
, p.
91
(
1978
).
2.
R. G.
Greaves
and
C. M.
Surko
,
Phys. Rev. Lett.
75
, p.
3846
(
1995
).
3.
W.
Oohara
and
R.
Hatakeyama
,
Phys. Rev. Lett.
91
, p.
205005
(
2003
).
4.
H.
Higaki
,
C.
Kaga
,
F.
Fukushima
,
H.
Okamoto
,
Y.
Nagata
,
Y.
Kanai
, and
Y.
Yamazaki
,
New J. Phys.
19
, p.
023016
(
2017
).
5.
G.
Sarri
,
K.
Poder
,
J. M.
Cole
,
W.
Schumaker
,
A.
Di Piazza
 et al,
Nature Comm.
6
, p.
6747
(
2015
).
6.
T. Sunn
Pedersen
,
J. R.
Danielson
,
C.
Hugenschmidt
,
G.
Marx
,
X.
Sarasola
,
F.
Schauer
,
L.
Schweikhard
,
C. M.
Surko
, and
E.
Winkler
,
New J. Physics
14
, p.
035010
(
2012
).
7.
E. V.
Stenson
,
J.
Horn-Stanja
,
M. R.
Stoneking
, and
T. Sunn
Pedersen
,
J. Plasma Phys.
83
, p.
595830106
(
2017
).
8.
C.
Hugenschmidt
,
C.
Piochacz
,
M.
Reiner
, and
K.
Schreckenbach
,
New J. Physics
14
, p.
055027
(
2012
).
9.
Z.
Yoshida
,
Y.
Ogawa
,
J.
Morikawa
,
H.
Himura
,
S.
Kondoh
,
C.
Nakashima
,
S.
Kakuno
,
M.
Iqbal
,
F.
Volponi
,
N.
Shibayama
, and
S.
Tahara
,
AIP Conf. Proc.
498
, p.
397
(
1999
).
10.
Z.
Yoshida
,
H.
Saitoh
,
J.
Morikawa
,
Y.
Yano
,
S.
Watanabe
, and
Y.
Ogawa
,
Phys. Rev. Lett.
104
, p.
235004
(
2010
).
11.
M.
Nishiura
,
Z.
Yoshida
,
H.
Saitoh
,
Y.
Yano
,
Y.
Kawazura
,
T.
Nogami
,
M.
Yamasaki
,
T.
Mushiake
, and
A.
Kashyap
,
Nucl. Fusion
55
, p.
053019
(
2015
).
12.
A. C.
Boxer
,
R.
Bergmann
,
J. L.
Ellsworth
,
D. T.
Garnier
,
J.
Kesner
,
M. E.
Mauel
, and
P.
Woskov
,
Nature Phys.
6
, p.
207
(
2010
).
13.
J. R.
Danielson
,
D. H. E.
Dubin
,
R. G.
Greaves
, and
C. M.
Surko
,
Rev. Mod. Phys.
87
, p.
247
(
2015
).
14.
J.
Stanja
,
U.
Hergenhahn
,
H.
Niemann
,
N.
Paschkowski
,
T. Sunn
Pedersen
,
H.
Saitoh
,
E. V.
Stenson
,
M. R.
Stoneking
,
C.
Hugenschmidt
, and
C.
Piochcz
,
Nucl. Instr. Meth. Phys. Res. A
827
, p.
52
(
2016
).
15.
H.
Saitoh
,
J.
Stanja
,
E. V.
Stenson
,
U.
Hergenhahn
,
H.
Niemann
,
T. Sunn
Pedersen
,
M. R.
Stoneking
,
C.
Piochacz
, and
C
Hugenschmidt
,
New J. Phys.
17
, p.
103038
(
2015
).
16.
A.
Hasegawa
,
Comments Plasma Phys. Control. Fusion
11
, p.
147
(
1987
).
17.
Z.
Yoshida
,
H.
Saitoh
,
Y.
Yano
,
H.
Mikami
,
N.
Kasaoka
,
W.
Sakamoto
,
J.
Morikawa
,
M.
Furukawa
, and
S. M.
Mahajan
,
Plasma Phys. Control. Fusion
55
, p.
014018
(
2013
).
18.
Y.
Kawazura
,
Z.
Yoshida
,
M.
Nishiura
,
H.
Saitoh
,
Y.
Yano
,
T.
Nogami
,
N.
Sato
,
M.
Yamasaki
,
A.
Kashyap
, and
T.
Mushiake
,
Phys. Plasmas
22
, p.
112503
(
2015
).
19.
M.
Schulz
and
L. J.
Lanzerotti
,
Particle Diffusion in the Radiation Belts
(
Springer
,
New York
,
1974
).
20.
X.-P.
Huang
,
F.
Anderegg
,
E. M.
Hollmann
,
C. F.
Driscoll
, and
T. M.
O’Neil
,
Phys. Rev. Lett.
78
, p.
875
(
1997
).
21.
J. R.
Danielson
and
C. M.
Surko
,
Phys. Rev. Lett.
94
, p.
035001
(
2005
).
22.
D. B.
Cassidy
,
R. G.
Greaves
,
V. E.
Meligne
, and
A. P.
Mills
, Jr.
,
Appl. Phys. Lett.
96
, p.
101502
(
2010
).
23.
U.
Hergenhahn
,
J.
Horn-Stanja
 et al,
AIP Conference Proc.
(this volume) (
2017
).
This content is only available via PDF.
You do not currently have access to this content.