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Journal ArticleDOI

A simple device of generating glow discharge plasma in atmospheric pressure argon

19 Oct 2007-Applied Physics Letters (American Institute of Physics)-Vol. 91, Iss: 16, pp 161507
TL;DR: In this article, the authors used optical emission spectroscopy to determine excited electron temperature and vibrational temperature, and the results indicated that the excited particle temperature and the molecular vibration temperature are about 6000 and 2300K, respectively.
Abstract: Atmospheric pressure glow discharge is realized in argon by using a plasma needle. With increasing the applied voltage, uniform plasma increases in scale from a small region near the needle tip to a plasma plume with a length of about 20mm. The discharge mechanism is discussed based on the light emission waveforms from the plasma. Optical emission spectroscopy is used to determine excited electron temperature and vibrational temperature, and the results indicate that the excited electron temperature and the molecular vibrational temperature are about 6000 and 2300K, respectively.

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Summary

  • With increasing the applied voltage, uniform plasma increases in scale from a small region near the needle tip to a plasma plume with a length of about 20 mm.
  • The discharge mechanism is discussed based on the light emission waveforms from the plasma.
  • Optical emission spectroscopy is used to determine excited electron temperature and vibrational temperature, and the results indicate that the excited electron temperature and the molecular vibrational temperature are about 6000 and 2300 K, respectively.

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A simple device of generating glow discharge plasma in atmospheric
pressure argon
Xuechen Li,
a
Lifang Dong, Na Zhao, and Zengqian Yin
College of Physics Science and Technology, Hebei University, Baoding 071002, People’s Republic of China
Tongzhen Fang and Long Wang
Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China
Received 6 September 2007; accepted 1 October 2007; published online 19 October 2007
Atmospheric pressure glow discharge is realized in argon by using a plasma needle. With increasing
the applied voltage, uniform plasma increases in scale from a small region near the needle tip to a
plasma plume with a length of about 20 mm. The discharge mechanism is discussed based on the
light emission waveforms from the plasma. Optical emission spectroscopy is used to determine
excited electron temperature and vibrational temperature, and the results indicate that the excited
electron temperature and the molecular vibrational temperature are about 6000 and 2300 K,
respectively. © 2007 American Institute of Physics. DOI: 10.1063/1.2800814
Research on atmospheric pressure glow discharges
APGDs is motivated by applications such as thin film
deposition, surface modification, sterilization, light sources,
plasma display panels, plasma cloaking for aircraft, etc.
High-pressure glow discharges are prone to instabilities,
which cause a transition from spatially uniform glow to an
arc filamentation. It must be damped. Much of the effort in
generating stable APGD has focused on preventing the onset
of instabilities. Multiple avalanches coupling at low break-
down voltage are necessary for generating APGD under
sinusoidal voltage excitation. APGD has been investigated in
helium and nitrogen theoretically and experimentally by nu-
merous authors,
1,2
and results show that interpulse preioniza-
tion resulting from metastable particles can provide an addi-
tional source of primary electrons, which lowers breakdown
voltage for a forthcoming half-cycle. Based on this view-
point, ultraviolet radiation produced by spark discharges is
employed by Qi et al. to supply preionization for realizing
APGD.
3
APGD is also realized in a device with a fine mesh
inserted between the electrode and the barrier layer. Wang et
al. explained that corona discharge around the mesh can pro-
vide interpulse electrons for APGD.
4
An alternative approach
for APGD is to restrict current growth by connecting a resis-
tor or a semiconductor in series with the discharge device,
5,6
though a pulse voltage on preventing the thermal instability
is commonly employed to generate APGD at current densi-
ties above threshold for the glow-to-arc transition.
7,8
An easy
solution to avoid glow-to-arc transition at atmospheric pres-
sure is to use microplasmas made in submillimetric scale. A
plasma needle is proposed by Stoffels and co-workers
9,10
which works under rf conditions and plasma is stabilized by
the flowing of working gas.
The focus of this paper is to present a plasma needle that
is excited by a power source with a frequency of several tens
of kilohertz. This simple and low cost device can generate
APGD plasmas in stagnant argon and electric matching does
not need to be considered. The basic aspects of this plasma
needle are discussed and plasma parameters are given.
A schematic drawing of the plasma needle is shown in
Fig. 1. Plasma is generated at the sharp end of a tungsten pin
tip radius can be adjusted from 70 to 100
m, the experi-
mental results are obtained with 90
m tip radius if no spe-
cial explanation is given. The pin is fixed by a piece of
rubber and it protruded from the holder by 3 cm. The total
length of the needle is about 5 cm. The plasma needle is
placed in a Perspex vacuum vessel. The vessel is pumped by
a mechanical pump to its limit and then argon 99.99% is
filled in to one atmospheric pressure. The blunt end of the
needle is connected to the high voltage output of a power
source. The frequency is fixed at 67 kHz. The applied volt-
age can be measured by a high voltage probe Tektronix
P6015A, 1000 and recorded with an oscilloscope Tek-
tronix TDS3054B, 500 MHz. For recording the discharge
images, a digital camera Canon Powershot G1:
3.24 Mpixels is used, and the exposure time is 8 ms in our
experiments. Light emission is detected by a photomultiplier
tube RCA7265. Optical emission spectrum is obtained by a
spectrometer equipped with a charge coupled device CCD
detector ACTON Research Spectropro2785, 1340
400 pixels with a grating of 2400 grooves mm
−1
. The en-
trance slit opening and the integration time of the CCD de-
tector are maintained at 0.1 mm and 3 ms, respectively.
Figure 2 shows a series of images of the discharge in
atmospheric pressure argon with an increasing peak value of
the applied voltage U
p
. It can be found that the discharge is
confined to the near region of the needle tip when U
p
is in
the range from breakdown voltage to about 4200 V. When
a
Author to whom correspondence should be addressed; electronic mail:
xcli@hbu.cn FIG. 1. Color online Schematic drawing of the experimental setup.
APPLIED PHYSICS LETTERS 91, 161507 2007
0003-6951/2007/9116/161507/3/$23.00 © 2007 American Institute of Physics91, 161507-1
Downloaded 05 Aug 2013 to 147.8.230.100. This article is copyrighted as indicated in the abstract. Reuse of AIP content is subject to the terms at: http://apl.aip.org/about/rights_and_permissions

U
p
exceeds 4200 V, the scale of the plasma increases
abruptly and shows a shape of a plume. With a further in-
crease of U
p
, the length of the plasma plume increases and
the plasma turns brighter and brighter. Consequently, it can
be found that the plasma needle has two discharge modes:
corona discharge with U
p
below 4200 V and plasma plume
discharge with U
p
above 4200 V, respectively. Figure 3 in-
dicates the scale of the plasma as a function of U
p
.Itis
obvious that the scale of the plasma is kept constant about
0.7 mm in corona discharge mode and increases with U
p
in
plasma plume discharge mode. From Fig. 3, it can also be
found that the plasma plume is longer when the tip radius is
bigger, while the scale of the plasma is almost the same
when the discharge is in corona discharge mode.
As shown in Fig. 4, the discharge in the corona mode
consists of a series of pulses with width of about 200 ns
shown in Fig. 4b. When U
p
is slightly above the break-
down voltage shown in Fig. 4a, there is only one dis-
charge pulse for 1 cycle of the applied voltage and the dis-
charge pulse always appears at the negative half-cycle. As U
p
increases, the pulse number of negative half-cycle discharge
also increases, as shown in Figs. 4c4e. The maximum
number of discharge pulse is 5, and small light emission
signal can be found at the positive half-cycle when U
p
is
high enough, as shown in Fig. 4e. Figure 4f indicates the
light emission for the plasma plume discharge mode. Obvi-
ously, a discharge hump its width is about 7
s is shown at
the positive half-cycle, while a hump its width is about
2
s and some discharge pulses with width of about 200 ns
are shown at the negative half-cycle.
The different waveforms may result from different dis-
charge mechanisms for corona mode and plasma plume
mode. In corona discharge mode, high-field region only ex-
ists at the vicinity near the needle tip. When the applied
electric field is above critical value for breakdown, the num-
ber of electrons increases in the high-field region because of
electron avalanche process. The drifting velocity of electrons
is very low when the electrons move to the low-field region.
Therefore, the negative potential needle tip is covered by an
electron cloud. Because of shielding effect of this electron
cloud, the electric field near the needle tip is lowered and the
discharge is quenched. As a result, the light emission wave-
form shows a pulse. As time passes by, there are two factors
for generating a consecutive discharge pulse. One is the in-
crement of the applied voltage because a sinusoidal wave-
form is used. The other is that the electrons covering the
needle tip move away because of slow drifting. Obviously,
the discharge emission shows a series of short-lived pulses.
Only discharge emission at the negative half-cycle is ob-
served because the breakdown field for negative potential is
lower than that for positive potential. However, when U
p
is
high enough, as shown in Fig. 4e, the electrons generated at
the negative half-cycle will run toward the needle tip to ex-
cite neutral atoms, hence, little light emission signal appears
at the positive half-cycle. The discharge mechanism at the
corona discharge mode is similar to that of dc negative co-
rona discharge. However, a different discharge mechanism is
involved for the plasma plume discharge mode. In the
plasma plume discharge, electrons move and accumulate at
FIG. 2. Color online Discharge images under different U
p
: a 4kV,b
6.5 kV, and c 9.5 kV.
FIG. 3. Color online Plasma length as a function of U
p
and tip radius.
FIG. 4. Color online Waveforms of the applied voltage and light emission
under different values of U
p
. b is an enlarged part of a. ae corre-
spond to the corona discharge mode shown in Fig. 2a. f corresponds to
that of a plasma plume.
161507-2 Li et al. Appl. Phys. Lett. 91, 161507 2007
Downloaded 05 Aug 2013 to 147.8.230.100. This article is copyrighted as indicated in the abstract. Reuse of AIP content is subject to the terms at: http://apl.aip.org/about/rights_and_permissions

the tail of the plasma plume at the negative half-cycle. When
the positive half-cycle comes, these accumulated electrons
will move toward the needle tip and ionize neutral atoms to
generate new electrons and positive ions. These positively
charged ions will drift toward the plasma plume tail and
accumulate there. Consequently, a virtual electrode is placed
at the tail of the plasma plume. For the negative half-cycle
discharge, electrons accumulate on this virtual electrode,
while for positive half-cycle discharge, electrons emit from
this electrode and positive ions accumulate on this electrode.
Because of this virtual electrode spatial charges, the elec-
tric potential distribution is different from that in the corona
discharge and the electric field in the whole gap between the
needle tip and the virtual electrode is high enough to form a
glow discharge. The virtual electrode is not grounded, so
glow-to-arc transition is damped. Therefore, a high-pressure
glow discharge is generated in the gap between the needle tip
and the virtual electrode.
Figures 5a and 5b indicate the optical emission spec-
tra in the range from 300 to 410 nm and 500 to 800 nm, re-
spectively. The intensity of the second positive system of N
2
is used to calculate the molecular vibrational temperature.
11
The spectral lines, 687.13, 696.54, and 772.42 nm, of argon
are chosen to determine the excited electron temperature us-
ing a Boltzmann plot.
12
The results show that the molecular
vibrational temperature is about 2300 K and the excited elec-
tron temperature is about 6000 K for the plasma plume dis-
charge mode. These plasma parameters are functions of the
experimental parameters such as U
p
, frequency, distance
from the tip, etc. More detailed work is under research and
will be published elsewhere.
This paper was sponsored by the National Natural Sci-
ence Foundation of China under Grant Nos. 10575027 and
10647123, and the National Natural Science Foundation of
Hebei province, China under Grant Nos. A2007000134 and
A2006000950.
1
S. Kanazawa, M. Kogoma, T. Moriwaki, and S. Okazaki, J. Phys. D 21,
838 1988.
2
F. Massines, N. Gherardi, N. Naude, and P. Segur, Plasma Phys. Con-
trolled Fusion 47, B577 2005.
3
B. Qi, C. S. Ren, D. Z. Wang, S. Z. Li, K. Wang, and Y. T. Zhang, Appl.
Phys. Lett. 89, 131503 2006.
4
X. X. Wang, H. Y. Luo, Z. Liang, T. Mao, and R. L. Ma, Plasma Sources
Sci. Technol. 15, 845 2006.
5
A. Risacher, S. Larigaldie, G. Bobillot, J. P. Marcellin, and L. Picard,
Plasma Sources Sci. Technol. 16, 200 2007.
6
Y. Yang, IEEE Trans. Plasma Sci. 31,1742003.
7
J. L. Walsh, J. J. Shi, and M. G. Kong, Appl. Phys. Lett. 89, 161505
2006.
8
K. Takaki, M. Hosokawa, T. Sasaki, S. Mukaigawa, and T. Fujiwara, Appl.
Phys. Lett. 86, 151501 2005.
9
E. P. van der Laan, E. Stoffels, and M. Steinbuch, Plasma Sources Sci.
Technol. 15, 582 2006.
10
I. E. Kieft, E. P. van der Laan, and E. Stoffels, New J. Phys. 6,1492004.
11
G. Herzberg, Molecular Spectra and Molecular Structure Science,
Beijing, 1983, Vol. I, pp. 273–275.
12
S. Forster, C. Mohr, and W. Viol, Surf. Coat. Technol. 200,8272005.
FIG. 5. Optical emission spectra in the range from a 300 to 410 nm and
b 500 to 800 nm U
p
=6 kV.
161507-3 Li et al. Appl. Phys. Lett. 91, 161507 2007
Downloaded 05 Aug 2013 to 147.8.230.100. This article is copyrighted as indicated in the abstract. Reuse of AIP content is subject to the terms at: http://apl.aip.org/about/rights_and_permissions
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In this paper, the authors used optical emission spectroscopy to determine excited electron temperature and vibrational temperature.