Magnetically confined cold-cathode plasmas in monatomic gases like helium can be used in a variety of devices and applications. In this paper, the radial distribution of electron temperature and electron density in cold-cathode helium plasmas constrained by an annular magnetic field were studied by optical emission spectroscopy. Helium plasma was generated under different pressures (7.5, 10, and 20 Pa) and values of current (23.5 and 33 mA). The spectral lines of He I 667.8 and He I 501.6 nm were studied and the Stark broadening method was applied to obtain the radial distributions of electron temperature and electron density. The results indicate that higher radial gradients or peak values of both electron density and electron temperature could be achieved with increasing operating pressures and discharge currents. It was found that the electrons were mainly concentrated in the area of the localized cusp magnetic field near the cathode surface and the electron density decreased rapidly as with the decrease in the magnetic field.

1.
S. N.
Abolmasov
, “
Physics and engineering of crossed-field discharge devices
,”
Plasma Sources Sci. Technol.
21
(
3
),
035006
(
2007
).
2.
E. M.
Oks
and
P. M.
Schanin
, “
Development of plasma cathode electron guns
,”
Phys. Plasmas
6
(
5
),
1649
1654
(
1999
).
3.
A. R.
Ellingboe
and
R. W.
Boswell
, “
Capacitive, inductive and heliconwave modes of operation of a helicon plasma source
,”
Phys. Plasmas
3
(
7
),
2797
2804
(
1996
).
4.
J. T.
Gudmundsson
, “
Physics and technology of magnetron sputtering discharges
,”
Plasma Sources Sci. Technol.
29
(
11
),
113001
(
2020
).
5.
A. T.
Powis
,
J. A.
Carlsson
,
I. D.
Kaganovich
,
Y.
Raitses
, and
S.
Andrei
, “
Scaling of spoke rotation frequency within a Penning discharge
,”
Phys. Plasmas
25
(
7
),
072110
(
2018
).
6.
A.
Anders
, “
Plasma and ion sources in large area coating: A review
,”
Surf. Coat. Technol.
200
(
5–6
),
1893
1906
(
2005
).
7.
A.
Anders
and
Y. C.
Yang
, “
Plasma studies of a linear magnetron operating in the range from DC to HiPIMS
,”
J. Appl. Phys.
123
(
4
),
043302
(
2018
).
8.
V. V.
Zhurin
,
H. R.
Kaufman
, and
R. S.
Robinson
, “
Physics of closed drift thrusters
,”
Plasma Sources Sci. Technol.
8
(
1
),
R1
R20
(
1999
).
9.
D. J.
Belknap
and
L. R.
Crump
, “
Lateral current control mechanism for cold cathode gas discharges
,”
J. Appl. Phys.
29
(
4
),
737
738
(
1958
).
10.
C. A.
Allen
,
W. N.
Hitchon
,
S. C.
Aceto
,
D. J.
Smith
,
T. J.
Sommerer
,
J. F.
Trotter
, and
J. E.
Lawler
, “
Erosion rates of diffuse and constricted magnetron discharges in helium over aluminium, gallium, molybdenum, and tantalum
,”
J. Phys. D
52
(
43
),
435203
(
2019
).
11.
D. J.
Smith
,
T. J.
Sommerer
,
J. E.
Lawler
, and
W. N. G.
Hitchon
, “
Voltage and cathode emission mechanisms of a magnetized, constricted, orbiting plasma in helium 6.7–850 Pa
,”
J. Phys. D
54
(
29
),
295201
(
2021
).
12.
T. J.
Sommerer
,
S. C.
Aceto
,
J. F.
Trotter
,
D. J.
Smith
,
C. A.
Allen
,
W. N. G.
Hitchon
, and
J. E.
Lawler
, “
Operating modes of a magnetized cold cathode plasma in helium 50–6400 mTorr
,”
J. Phys. D
52
(
43
),
435202
(
2019
).
13.
D. M.
Goebel
, “
Cold-cathode, pulsed-power plasma discharge switch
,”
Rev. Sci. Instrum.
67
(
9
),
3136
(
1996
).
14.
R. L.
Jepsen
, “
Magnetically confined coldcathode gas discharges at low pressures
,”
J. Appl. Phys.
32
(
12
),
2619
2626
(
1961
).
15.
A. B.
Murphy
, “
Thermal plasmas in gas mixtures
,”
J. Phys. D
34
(
20
),
R151
R173
(
2001
).
16.
H. T.
Zhang
,
Y.
Wu
,
H.
Sun
,
F.
Yang
,
M. Z.
Rong
,
F. F.
Jiang
,
C. L.
Wang
, and
W.
Huang
, “
Application of calibration-free Boltzmann plot method for composition and pressure measurement in argon free-burning arcs
,”
Plasma Chem. Plasma Process.
39
(
6
),
1429
1447
(
2019
).
17.
S.
Zielińska
,
K.
Musioł
,
K.
Dzierżęga
,
S.
Pellerin
,
F.
Valensi
,
C.
Izarra
, and
F.
Briand
, “
Investigations of GMAW plasma by optical emission spectroscopy
,”
Plasma Sources Sci. Technol.
16
(
4
),
832
838
(
2007
).
18.
F.
Valensi
,
S.
Pellerin
,
A.
Boutaghane
,
K.
Dzierżęga
,
S.
Zielińska
,
S.
Pellerin
, and
F.
Briand
, “
Plasma diagnostics in gas metal arc welding by optical emission spectroscopy
,”
J. Phys. D
43
(
43
),
434002
(
2010
).
19.
G.
Pretzier
, “
A new method for numerical Abel-inversion
,”
Z. Nat.
46
(
7
),
639
641
(
1991
).
20.
G.
Pretzier
,
H.
Jäger
,
T.
Neger
, and
J.
Woisetschläger
, “
Comparison of different methods of Abel inversion using computer simulated and experimental side-on data
,”
Z. Nat.
47
(
9
),
955
970
(
1992
).
21.
A.
Ionascut-Nedelcescu
,
C.
Carlone
,
U.
Kogelschatz
,
D. V.
Gravelle
, and
M. I.
Boulos
, “
Calculation of the gas temperature in a throughflow atmospheric pressure dielectric barrier discharge torch by spectral line shape analysis
,”
J. Appl. Phys.
103
(
6
),
063305
(
2008
).
22.
G. V.
Vogman
and
U.
Shumlak
, “
Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch
,”
Rev. Sci. Instrum.
82
(
10
),
103504
(
2011
).
23.
J. J.
Olivero
and
R.
Longbothum
, “
Empirical fits to the Voigt line width: A brief review
,”
J. Quant. Spectrosc. Radiat. Transfer
17
(
2
),
233
236
(
1977
).
24.
A. Y.
Nikiforov
,
C.
Leys
,
M. A.
Gonzalez
, and
J. L.
Walsh
, “
Electron density measurement in atmospheric pressure plasma jets: Stark broadening of hydrogenated and non-hydrogenated lines
,”
Plasma Sources Sci. Technol.
24
(
3
),
034001
(
2015
).
25.
C.
Perez
,
I.
Delarosa
,
A. M.
Defrutos
, and
S.
Mar
, “
Calibration of the Stark-broadening parameters for some He I lines
,”
Phys. Rev. A
44
(
10
),
6785
6790
(
1991
).
26.
L.
Malter
, “
Thin film field emission
,”
Phys. Rev.
50
(
48
),
48
(
1936
).
27.
J.
Evertsson
,
F.
Bertram
,
F.
Zhang
,
L.
Rullik
,
L. R.
Merte
,
M.
Shipilin
,
M.
Soldemo
,
S.
Ahmadi
,
N.
Vinogradov
,
F.
Carla
,
J.
Weissenrieder
,
M.
Gothelid
,
J.
Pan
,
A.
Mikkelsen
,
J. O.
Nilsson
, and
E.
Lundgren
, “
The thickness of native oxides on aluminum alloys and single crystals
,”
Appl. Surf. Sci.
349
,
826
832
(
2015
).
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