Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles
Influence of air and water molecules detached from the chamber walls under ion impacts on UV radiation from hollow cathode discharge plasma in oxygen, nitrogen, and air is studied. Dependencies of UV radiation intensity and dose on the discharge glow duration, working gas type and pressure, and the...
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| Zitieren: | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles / V.V. Tsiolko, V.Yu. Bazhenov, V.A. Khomich, V.M. Piun // Вопросы атомной науки и техники. — 2010. — № 4. — С. 234-239. — Бібліогр.: 12 назв. — англ. |
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| author | Tsiolko, V.V. Bazhenov, V.Yu. Khomich, V.A. Piun, V.M. |
| author_facet | Tsiolko, V.V. Bazhenov, V.Yu. Khomich, V.A. Piun, V.M. |
| citation_txt | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles / V.V. Tsiolko, V.Yu. Bazhenov, V.A. Khomich, V.M. Piun // Вопросы атомной науки и техники. — 2010. — № 4. — С. 234-239. — Бібліогр.: 12 назв. — англ. |
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| description | Influence of air and water molecules detached from the chamber walls under ion impacts on UV radiation from hollow cathode discharge plasma in oxygen, nitrogen, and air is studied. Dependencies of UV radiation intensity and dose on the discharge glow duration, working gas type and pressure, and the discharge power are determined.
Исследовано влияние примесей молекул воздуха и воды, оторванных от стенок камеры под действием ионных ударов, на УФ-излучение плазмы разряда с полым катодом на кислороде, азоте и воздухе. Установлены зависимости интенсивности и дозы УФ-излучения от длительности горения разряда, вида рабочего газа, его давления и мощности в разряде.
Досліджено вплив домішок молекул повітря та води, відірваних зі стінок камери під впливом іонних ударів, на УФ-випромінювання плазми розряду з порожнистим катодом на кисні, азоті та повітрі. Встановлено залежності інтенсивності та дози УФ-випромінювання від тривалості горіння розряду, виду робочого газу, його тиску та потужності в розряді.
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ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2010. № 4.
Серия: Плазменная электроника и новые методы ускорения (7), с.234-239.
234
PECULIARITIES OF UV RADIATION FROM HOLLOW CATHODE
DISCHARGE PLASMA USED FOR STERILIZATION OF MEDICAL
ARTICLES
V.V. Tsiolko, V.Yu. Bazhenov, V.A. Khomich, V.M. Piun
Institute of Physics of National Academy of Sciences of Ukraine, Kiev, Ukraine
E-mail: tsiolko@iop.kiev.ua
Influence of air and water molecules detached from the chamber walls under ion impacts on UV radiation from
hollow cathode discharge plasma in oxygen, nitrogen, and air is studied. Dependencies of UV radiation intensity and
dose on the discharge glow duration, working gas type and pressure, and the discharge power are determined.
PACS: 52.80.Hc, 52.70.Kz, 52.25.Os
1. INTRODUCTION
A novel technique for sterilization of medical in-
struments by gas discharge plasma offers many promis-
ing features (efficiency, reliability, low temperature of
processed items) in comparison with conventional ster-
ilization methods – dry or moist heat, chemical treat-
ments by EtO. It was shown in [1,2] for the first time
that in the case of gaseous plasma generating media
main role in the sterilization of open surfaces is per-
formed by ultraviolet radiation of the plasma. In subse-
quent years, different aspects of both generation of UV
radiation by the plasmas of low pressure discharges, and
action of this radiation on the microorganisms were stu-
died in multiple proceedings. However, all researches of
the sterilization efficiency in different wavelength
ranges of VUV/UV radiation from a discharge plasma
were performed at stable and controlled system parame-
ters, that is with permanent in time component content
of a gas mixture, its pressure / gas flow, etc. In case of
actual plasma sterilizers based on low pressure dis-
charges the situation is somewhat more complicated.
Ultimate parameters of a sterilizer are minimum sterili-
zation time (more correctly, minimum time from load-
ing to unloading of processed items), and the design
simplicity. These requirements to the device are in a
certain contradiction with experimental conditions listed
above, because through working chamber evacuation
with removal of atmospheric air residuals (N2, O2, water
vapor) is required for providing stable and controllable
content of required gas mixture. And the last can be don
only at the expense of prolongation of evacuation time
and the use of high vacuum pumps.
Experimental researches of sterilization efficiency
by UV radiation under actual conditions, that is with
varying in time component content of the gas mixture in
the discharge due to atmospheric air admixtures to
working gas (nitrogen, oxygen, argon) were performed
in [3]. It has been determined that higher inactivation
efficiency by UV radiation of the discharge plasma on
oxygen is due to peculiarities of its emission spectra,
particularly, high radiation intensity in wavelength
range ≈ 215…230 nm.
Due to that, purpose of our work consisted in the
study of peculiarities of generation of UV radiation by
hollow cathode discharge plasma in nitrogen, oxygen
and air with О2, N2 and H2O admixtures.
2. DESCRIPTION OF SETUP AND METHODS
The experiments were performed at setup which was
described in details in [2]. Plasma was formed by means
of direct current discharge inside cylindrical chamber
with 260 mm diameter and 420 mm length (which si-
multaneously served as hollow cathode of the dis-
charge). Oxygen, nitrogen and ambient air were used as
working gases. Specific power introduced into the dis-
charge was varied in a range of 0.0025…0.0125 W/cm3.
Temperature of water cooled chamber walls was about
20°C.
Measurements of spectrum dependencies of the
plasma UV radiation in wavelength range of
200…300 nm on the discharge glow time tg were per-
formed by means of spectrometer SL40-2-2048USB
(SOLAR TII, Ltd). At the measurements, the end of
quartz waveguide of the spectrometer was located in a
plane which corresponded to placement of Petri dishes
with Bac.subtilis spores during medical-biological re-
searches.
Due to fact that experimental studies of decontami-
nation efficiency of Bac. subtilis spores were performed
with the use of UV radiation with essentially different
spectrum shape, in this proceeding the method of de-
termining effective irradiation fluence for studied sam-
ple was used which enabled correct comparison of the
results obtained with the use of mentioned UV sources.
Essence of the method consisted in “weighing” spectral
irradiance values for each used type of UV radiation.
At determination of “weighing” function, first of all,
results of works [7, 8] devoted to studies of DNA mole-
cule absorption and efficiency of bactericidal action of
UV radiation on the microorganisms in dependence on
the radiation frequency were taken into account. It has
been shown in [4] that DNA absorption spectrum in
considered wavelength range (≈180…300 nm) repre-
sents superposition of broad absorption bands having
maxim at about 190 and 260 nm due to electron excita-
tion of diene and triene fragments of DNA molecule
chain. In experiments with Bacillus subtilis spores [5] it
has been shown that spores inactivation action spectra
(i.e. dependence inactivation rate vs UV wavelength)
has more complicated behavior in comparison with
DNA absorption spectrum. In wavelength range
50…300 nm the spores inactivation rate has peaks at
≈ 150 nm, ≈ (220…230) nm and ≈ (260…270) nm.
(Such difference is most likely due to absorption of ra-
diation by the structures surrounding DNA – exospo-
rium, plasma membranes, protoplast, etc.). In our work
we used “weighing” function (Fig.1) obtained by multi-
plying inactivation action spectra for Bac. subtilis
spores type RCF from [5] and transmission curve of
KU-1 filter.
235
0150 175 200 225 250 275 30
0,0
0,2
0,4
0,6
0,8
1,0
ΙΙΙ
3
2
1
A.
U
.
Wavelength, nm
Fig.1. 1 − Bac. subtilis spores inactivation action spec-
trum; 2 − transmission curve of quartz KU-1 filter with
3-mm thickness; 3 − “weighing” curve, obtained by
multiplying of the spores inactivation action spectrum
and transmission curve of KU-1 filter
Dash-dot vertical line represents bottom boundary
(200 nm) of spectra measurements of UV radiation from
the discharge plasma. (It should be noted that, at the use
of “weighing” function of the inactivation spectra for
others spore types from [8], obtained values of
“weighed” UV fluence rate Ew and fluence Hw of the
radiation differ by no more than 15…20%).
Procedure of accomplishing the experiments on ster-
ilization / radiation spectra measurement was, as fol-
lows:
- the chamber was filled by air up to atmospheric
pressure after glow of the discharge with particular pa-
rameters (working gas type, pressure, specific power in
the discharge Wd);
- Petri dishes with Bac. Subtilis spores were unloaded
from / loaded to the chamber (with about 10 minutes
duration of the procedure), or the chamber was held at
atmospheric pressure for the same time in case of UV
spectra measurements;
- the chamber was evacuated by means of forevacuum
pump down to residual air pressure of about 1 Pa;
- after that the chamber was purged by working gas at
working pressure for 5…10 minutes;
- in subsequent, the discharge was ignited in the
chamber with predetermined specific power Wd and the
sterilization was performed, or the plasma UV radiation
spectra were measured in dependence on the discharge
glow time tg;
- the discharge was turned off, the chamber was filled
by ambient air up to atmospheric pressure, unloading /
loading of Petri dishes was performed, or the chamber
was held at atmospheric pressure for about 10 minutes;
- the same procedure of sterilization / UV radiation
spectra measurements was repeated for other gas type,
working pressure in the chamber, specific power in the
discharge Wd.
Due to fact that prior to evacuation the chamber was
held for a long time at atmospheric pressure, air and
water vapor were adsorbed at the walls. Chamber evac-
uation and purge by working gases did not remove ad-
sorbed particles from the walls completely (first of all,
oxygen and water molecules), and due to that they were
admixed with working gas at the expense of “knocking
down” by fast plasma ions. Thus, the discharge glow
occurred in working gas with admixtures of detached air
and water molecules, at that content of these admixtures
decreased with time tg.
3. MEASUREMENTS OF SPECTRA OF UV
RADIATION FROM THE DISCHARGE
PLASMA IN A RANGE OF 200…300 nm
Fig.2 shows “weighed” spectrum intensity distribu-
tions of UV radiation obtained at the discharge glow
with different working media.
200 220 240 260 280 300
0
10
20
30
40
50
60
(a)
U
V
In
te
ns
ity
, a
.u
.
Wavelength, nm
a
200 220 240 260 280 300
0
10
20
30
40
50
60
(b)b
U
V
In
te
ns
ity
, a
.u
.
Wavelength, nm
200 220 240 260 280 300
0
40
80
120
160
200
240
(c)
U
V
In
te
ns
ity
, a
.u
.
Wavelength, nm
c
Fig.2. Distributions of “weighed” intensity of UV radia-
tion over spectrum on different working media of the
discharge: a − oxygen; b – nitrogen; c − air.
Pressure Р= 15.6 Pa, Wd = 0.08 W/cc, duration
of discharge glowing td = 240 s
As one can see from analysis of these spectra, at
oxygen use main contribution to UV radiation of the
plasma occurs due to emission of the second negative
system (SNS) O2
+ (А2Пu – X2Пg) and Schumann-Runge
system (SRS) O2 (B3Σu
- – X3Σg
-), and at the use of am-
bient air and nitrogen due to emission of γ system NO
(A2∑+ - X2П). (Occurrence of radiation of γ system NO
in the discharge plasma in nitrogen is due to presence of
oxygen molecules at the expense of their detachment
from the chamber walls under action of the fast plasma
ions). One can see from comparison of Fig.2,a,b,c that
in case of oxygen use main “weighed” power of UV
radiation is concentrated in spectrum range of
≈ 210…230 nm, whereas at the use of air and nitrogen
power of UV radiation is spread over several bands in
range of ≈ 210…260 nm.
As it was already noted above, at accomplishing the
measurements component content of the gas in the
chamber could somewhat vary at the time of the dis-
charge glow tg due to air and water vapor detachment
from the chamber walls by flows of high-energy
(W ≈ 400…600 eV) ions from the discharge plasma.
Respectively, this effect can lead to dependence of UV
radiation spectrum intensity and/or shape on time tg.
However, spectra measurements have shown that in a
range of working pressure gas (oxygen, nitrogen and
air) in the chamber of ≈ 4…25 Pa detachment of gases /
vapors from the chamber walls has no significant effect
on UV radiation spectrum shape in wavelength range of
200…300 nm. An exclusion is represented by the dis-
charge in oxygen at ≈ 4…7 Pa pressure, when for initial
40…50 s of the discharge glow, in addition to radiation
of O2 and O2
+ molecules, bands of γ system NO are also
observed in UV spectrum. At the same time, value of
“weighed” fluence rate Ew of UV radiation in this wave-
length range essentially depends on both tg , and work-
ing gas pressure in the chamber, at that these dependen-
cies are different for various working gases
(Fig.3,а,b,c).
236
Common behavior for all Ew dependencies consists
in rapid growth of UV radiation intensity during initial
≈ 40…60 s, and after that their behavior in time depends
on particular values of pressure and working gas type.
This initial rapid growth of Ww is, first of all, due to
pressure variations in the chamber at the discharge turn-
ing on. (At the discharge turning on, pressure in the
chamber initially (for about 1 s) exhibits a jump by
∆ Р ≈ 2…3 Pa, and after that for ∼ 40…60 s decreases
monotonously down to predetermined pressure value in
the chamber.) Plasma radiation intensity growth for this
time period is, first of all, due to fact that pressure de-
crease in the chamber results in a growth of mean en-
ergy of the plasma electrons and, consequently, to in-
crease of rates of elementary processes with participa-
tion of electrons.
In subsequent, (at tg > ∼ (40…60) s) when pressure
in the chamber comes to its quasistationary value, be-
havior of Ew dependencies on tg is, first of all, deter-
mined by ratios between concentrations of O2, N2 and
H2O molecules detached from the walls and working
gas concentrations. Let us consider in more details Ww
dependencies on time at tg > ( ∼ 30…60) s.
One can see from Fig.3,a that in case of the dis-
charge in oxygen UV radiation fluence rate Ew at higher
gas pressures is practically independent on tg , and mo-
notonously decreases with oxygen pressure increase in
the chamber. However, at oxygen pressure of about 4 Pa
behavior of Ew dependence on time is different – UV
radiation intensity reaches its maximum at about 30 s of
the discharge glow, after that it starts a decrease until its
minimum at ≈ 150 s, and then it starts a growth again.
(It should be noted that similar behavior of Ew depend-
ence on time tg is also observed at 7 Pa pressure, al-
though its non-monotony is exhibited not so obviously).
This effect may result from EEDF “depletion” in a
range of ≈ (10…30 eV) due to losses of electron energy,
first of all, for H2O dissociation and OH excitation.
And, since excitation cross sections of SRS О2 and SNS
О2
+ are approximately in the same energy range, such
EEDF “depletion” results in decrease of intensity of UV
radiation from oxygen plasma.
0 100 200 300 400 500 600
0
200
400
600
800
1000
1200
1400
1600
5
4
3
2
1
a)
U
V
"w
ei
gh
ed
" f
lu
en
ce
ra
te
E
w
, a
.u
.
Time t , s
0 200 400 600 800 1000 1200
0
200
400
600
800
1000
1200
a
g
5
4
3
2
1
U
V
"w
ei
gh
ed
" f
lu
en
ce
ra
te
E
w
, a
.u
.
Time t , s
0 200 400 600 800 1000 1200
0
400
800
1200
1600
2000
2400
b)b
g
c)c
5
4
3
2
1
U
V
'w
ei
gh
ed
' f
lu
en
ce
ra
te
E
w
a.
u.
Time t , s
g
Fig.3. Dependence of “weighed” fluence rate E
w of UV
radiation in wavelength range of 200…300 nm on the
discharge glow time tg at different pressure values Р:
a - oxygen; b - nitrogen; c - air. 1 - 4.5 Pa; 2 - 7.0 Pa;
3 - 11 Pa; 4 – 15 Pa; 5 – 21 Pa; Wd = 0.08 W/cc
Unlike the case of the discharge in oxygen, Ew value
of UV radiation for the discharge in nitrogen continues
a growth in time as well after ≈ 30…40 s of the dis-
charge glow, however, with slower rate, and in subse-
quent, after reaching its maximum, it starts a decrease.
At that, increase of nitrogen pressure in the chamber
from ≈ 4 up to 20 Pa results in decrease of a time of
reaching Ww maximum values from ≈ 300 s down to
≈ 100 s. Such behavior of Ew dependencies on tg is, first
of all, due to temporal variations of O2 and H2O concen-
trations in the chamber. For this reason, let us consider
in more details main elementary processes which de-
termine NO(A) concentration (and, consequently, UV
radiation intensity of γ system NO) in our discharge
plasma in nitrogen with O2 and H2O admixtures. It was
determined in [6,7] that in a plasma of positive column
of glow discharge in N2-O2 mixture main channel of
NO(A) birth is represented by reaction:
N2(A) + NO(X) = N2(X) + NO(A), (1)
k = 6.6⋅10-11 cm3·s−1.
In turn, NO(X) concentration in such discharge is
mainly determined by ratio of rates of birth and death in
reactions (2)-(4) and (5), respectively:
N2(X, v≥13) + O → NO(X) + N(4S), (2)
k = 10-13 cm3s−1;
N2(A) + O = NO(X) + N(2D), (3)
k = 7⋅10-12 cm3s−1;
N(4S) + O2 = NO(X) + O, (4)
k = 1.1⋅10-14 *T*exp(3150/T) cm3s−1;
N(4S) + NO = N2(X,v≈3) + O, (5)
k = 1.05⋅10-12 * (T)0.5 cm3s−1.
Fig.4 exhibits experimentally measured dependen-
cies of UV radiation intensity of γ system NO and
weighed power of UV radiation Ww of our discharge
plasma on oxygen content η in N2-O2 mixture. One can
see that mentioned above dependencies show non-
monotonous behavior – their initial growth changes to
decrease at η ≈ 25%, at that radiation intensity of γ sys-
tem NO in subsequent (at η ≈ (75…80)%) falls down
practically to zero value, and Ew retains finite value due
to contribution of oxygen UV radiation. Such behavior
of γ system NO is determined by fact that the dependen-
cies of N2(A) and NO(X) concentrations on oxygen con-
tent in the gas mixture also possess non-monotonous
behavior, at that N2(A) concentration reaches its maxi-
mum value at lower η values [7].
0 10 20 30 40 50 60 70 80
0
20
40
60
80
100
120
NO, 237 nm
E
w
23
7
nm
in
te
ns
ity
, f
lu
en
ce
ra
te
E
w
, a
.u
.
Oxygen content η, %
Fig.4. Dependencies of radiation intensity of γ system
NO (λ = 237 nm) and “weighed” fluence rate Ew
on oxygen content in N2 - O2 mixture.
P = 8 Pa, tg = 240 s, Wd = 0.08 W/cc
It also follows from Fig.4 that in case of our discharge
in nitrogen Ew value (as it was noted above, it is actually
radiation of γ system NO) after tg ≥ 40…60 s (that is,
after establishing stationary value of gas mixture pressure
in the chamber) should decrease in time, since concentra-
tion of molecular oxygen admixture in the discharge vol-
ume decreases in a process of the chamber evacuation.
However, as one can see from Fig.3,b, such behavior of
Ew is observed only at high nitrogen pressure in the dis-
charge chamber, whereas at low pressure values Ew con-
tinues a growth until tg ≈ 400 s, and only after that starts a
decrease. From our viewpoint, such behavior of Ew is due
to water vapor influence (more exactly, ОН(Х) and Н
particles which arise at H2O decomposition in the dis-
charge plasma) on N2(A) concentration. Particularly, in
[8-10] it was shown that N2(A) deactivation in reactions
with ОН(X) and Н
N2(A) + OH(X) = N2(X) + OH(A), (6)
N2(A) + H = N2H, (7)
237
occurs with a very high rate constant – about
1⋅10-10 cm3·s−1.
Thus, we see that water vapor adding to N2-O2 mix-
ture results in decrease of concentration of N2(A) and,
respectively, NO(A). In case of our discharge in nitro-
gen it means that Ew in each time point tg is determined
by “competitive” influence of O2 and H2O admixtures
on NO(A) concentration. On one side, decrease of oxy-
gen admixture in time should lead to diminishing con-
centrations of O and NO(X) (and in the last case
NO(A), respectively). But, from another side, decrease
of water vapor amount in the discharge promotes in-
crease of NO(A) concentration due to lower expense of
N2(A) to excitation of hydroxyl radicals OH(X). Thus, if
for certain time rate of vapor removal from the chamber
exceeds rate of oxygen leaving, it can result in increase
of NO(A) concentration, even if quantity of NO(X) mo-
lecules in the chamber decreases at that. At low nitrogen
pressure influence of mentioned above processes on
NO(A) concentration and, consequently, on UV radia-
tion intensity, is more evident due to higher relative
contribution of water vapor admixture to total pressure
in the chamber.
Let us consider now Ew behavior in case of the dis-
charge in ambient air. As it was already mentioned
above, UV radiation intensity Ww in this case increases
monotonously in time at all used pressure values of am-
bient air. At the use of air as working gas, influence of
oxygen admixture coming from the chamber walls on
behavior of Ew dependence on tg should be considerably
less due to relative smallness of the amount of this ad-
mixture, as compared to oxygen amount in air. Due to
that, NO(A) concentration (and, consequently, Ew value)
in each time point should be mainly determined only by
the processes of quenching N2(A) excited molecules by
ОН(X) and H particles. Thus, with a decrease of amount
of water vapor amount detached from the chamber walls
Еw value should grow up. Behavior of temporal depend-
encies of O2 and H concentrations in our experiments is
estimated by radiation of Schumann-Runge system O2
and Balmer line of hydrogen Hα (radiation intensities of
these particles are, in the first approximation, propor-
tional to their densities, since their excitation occurs
only by electron impacts). One can see from Fig.5 that
the intensity of radiation of oxygen molecules diminishes
in time rather quickly, and already at tg ≈ 100 s reaches its
quasistationary value (that is, О2 concentration in the
chamber returns to the value corresponding the content in
ambient air).
0 100 200 300 400 500 600
0
100
200
300
400
500
600
700
2
1In
te
ns
ity
, a
.u
.
Time t
g
, s
Fig.5. Dependencies of radiation intensities of certain
lines of plasma particles of the discharge in ambient air
on glow time tg. 1 - Hα, 656.3 nm, 2 - O2 (Schumann-
Runge system), 219.4 nm. P = 8 Pa, Wd = 0.08 W/cc
At the same time, decrease of Balmer hydrogen line
Hα radiation intensity (in other words, water vapor con-
centration) occurs considerably slower (practically “syn-
chronously” with Ew value growth), thus approving the
assumption expressed by us.
As it was already mentioned above, Ew depends not
only on the discharge glow time tg, but as well on gas
pressure in the discharge chamber. One can see from
Fig. 6 that in case of oxygen use Ew decreases monoto-
nously with pressure increase in a whole used range of
oxygen pressure, and curves of Ew dependencies for the
discharges in air and nitrogen possess a maximum.
2 4 6 8 10 12 14 16 18 20 22 24
0
200
400
600
800
1000
1200
1400
1600
1800
2000
c)
b)
a)
U
V
flu
en
ce
ra
te
E
w,
a.
u.
Pressure P, Pa
238
Fig.6. Dependence of “weighed” fluence rate Ew of UV
radiation on pressure of gases: a - oxygen; b - nitrogen;
c - ambient air at tg = 240 s. Wd = 0.08 W/cc
It should be noted that 1) in spite of fact that main
channel of NO(A) generation is reaction (1) with par-
ticipation of only electrically neutral particles, concen-
tration of the last is determined by processes with par-
ticipation of electrons; 2) our previous researches have
shown that, at constant specific power introduced into
the discharge, plasma concentration is practically inde-
pendent on pressure variation in a range of
≈ (4…20) Pa. Due to that, in all cases Ew behavior is
determined by ratio of the rates of concentration growth
for oxygen and nitrogen molecules and by decrease of
the rates of reactions of their dissociation and excitation
by electron impact at pressure increase (the last results
in diminishing mean energy of the plasma electrons and,
consequently, in decrease of rates of these reactions).
That is, in case of the discharge in oxygen the reason of
monotonous Ew decrease with pressure growth is due to
fact that, in all range of Р variation, excitation rates of
SNS O2
+ and SRS O2 fall down faster than О2 concen-
tration grows up. Respectively, presence of maximum at
Ew dependencies on Р at the use of nitrogen and ambient
air is due to lower, as compared to the case of oxygen,
pace of diminishing the rates of oxygen dissociation
reactions and excitation of nitrogen vibration levels. Let
us consider in more details the reasons of such differ-
ence in paces of diminishing the rates of these elemen-
tary processes with pressure variation. In the first ap-
proximation, rates of the processes with participation of
electrons k ∼ σ(ε)*f(ε), where σ(ε) is the process cross
section, f(ε) is plasma electron energy distribution func-
tion. As it is known [11,12], threshold energies for cross
sections of oxygen dissociation and excitation of nitro-
gen vibration levels are lower than threshold energies
for cross sections of excitation of SNS O2
+ and SRS O2.
And, since at decrease of mean energy of plasma elec-
trons with gas pressure growth electron quantity in a
range of cross sections of oxygen dissociation and exci-
tation of nitrogen vibration level falls down slower than
in a range of cross sections of excitation of SNS O2
+ and
SRS O2, this results in lower rates of reactions of O2
dissociation and excitation of N2 vibration levels, as
compared to the rates of reactions of excitation of O2
and O2
+. Here it should be also noted that in case of the
discharge in nitrogen the behavior of Ew dependence on
P is influenced by oxygen concentration decrease, as
nitrogen pressure in the discharge chamber increases.
Respective decrease of NO(X) concentration results in
fact that Ew reaches its maximum values at lower gas
pressure, as compared to the case of ambient air use.
It has been already determined that for all used gases
fluence Fw of UV radiation practically linearly grows
with tg (see. Fig.7), at that Fw value for the discharge
plasma in ambient air considerably exceeds UV fluence
for the discharges in oxygen and nitrogen (which are
close in their values) in the whole range of tg variation.
c
a
b
0 200 400 600 800 1000 1200
0,0
0,2
0,4
0,6
0,8
1,0
1,2
c)
a)
b)
U
V
flu
en
ce
F
w
, a
.u
.
Time t
d
, s
c
b
a
Fig.7. Dependencies of “weighed” fluence Fw of UV
radiation on the discharge glow time tg: a - oxygen; b -
nitrogen; c - ambient air. Wd = 0.08 W/cc, P = 15 Pa
The experiments have also shown that at all gas
pressure values UV fluence value grows up linearly
with the increase of power introduced into the discharge
Wd (Fig.8 represents respective dependencies for the
case of the discharge in ambient air at pressure of
16.4 Pa).
0,03 0,04 0,05 0,06 0,07 0,08 0,09
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
U
V
F
lu
en
ce
F
w
, a
.u
.
Power Wd, W/cc
500 s
300 s
200 s
100 s
Fig.8. Dependencies of “weighed” fluence Fw of UV
radiation on specific power in the discharge Wd
at the use of ambient air for different time points tg.
P = 16.4 Pa
REFERENCES
1. V.A. Khomich, I.A. Soloshenko, V.V. Tsiolko, et al.
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239
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3 2 2
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Статья поступила в редакцию 31.05.2010 г.
ОСОБЕННОСТИ УЛЬТРАФИОЛЕТОВОГО ИЗЛУЧЕНИЯ ПЛАЗМЫ РАЗРЯДА С ПОЛЫМ
КАТОДОМ, ИСПОЛЬЗУЕМОГО ДЛЯ СТЕРИЛИЗАЦИИ МЕДИЦИНСКИХ ИЗДЕЛИЙ
В.В. Циолко, В.Ю. Баженов, В.А. Хомич, В.М. Пиун
Исследовано влияние примесей молекул воздуха и воды, оторванных от стенок камеры под действием
ионных ударов, на УФ-излучение плазмы разряда с полым катодом на кислороде, азоте и воздухе. Установ-
лены зависимости интенсивности и дозы УФ-излучения от длительности горения разряда, вида рабочего
газа, его давления и мощности в разряде.
ОСОБЛИВОСТІ УЛЬТРАФІОЛЕТОВОГО ВИПРОМІНЮВАННЯ ПЛАЗМИ РОЗРЯДУ
З ПОРОЖНИСТИМ КАТОДОМ, ЩО ВИКОРИСТОВУЄТЬСЯ ДЛЯ СТЕРИЛІЗАЦІЇ
МЕДИЧНИХ ВИРОБІВ
В.В. Ціолко, В.Ю. Баженов, В.О. Хомич, В.М. Піун
Досліджено вплив домішок молекул повітря та води, відірваних зі стінок камери під впливом іонних
ударів, на УФ-випромінювання плазми розряду з порожнистим катодом на кисні, азоті та повітрі. Встанов-
лено залежності інтенсивності та дози УФ-випромінювання від тривалості горіння розряду, виду робочого
газу, його тиску та потужності в розряді.
http://www.iop.org/EJ/search_author?query2=M%20Kogoma&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1
http://www.iop.org/EJ/search_author?query2=T%20Moriwaki&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1
http://www.iop.org/EJ/search_author?query2=S%20Okazaki&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1
http://www.iop.org/EJ/search_author?query2=M%20Kubo&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1
http://www.iop.org/EJ/search_author?query2=M%20Kogoma&searchfield2=authors&journaltype=all&datetype=all&sort=date_cover&submit=1
ОСОБЛИВОСТІ УЛЬТРАФІОЛЕТОВОГО ВИПРОМІНЮВАННЯ ПЛАЗМИ РОЗРЯДУ
З ПОРОЖНИСТИМ КАТОДОМ, ЩО ВИКОРИСТОВУЄТЬСЯ ДЛЯ СТЕРИЛІЗАЦІЇ
МЕДИЧНИХ ВИРОБІВ
|
| id | nasplib_isofts_kiev_ua-123456789-17337 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-28T17:46:50Z |
| publishDate | 2010 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Tsiolko, V.V. Bazhenov, V.Yu. Khomich, V.A. Piun, V.M. 2011-02-25T13:47:19Z 2011-02-25T13:47:19Z 2010 Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles / V.V. Tsiolko, V.Yu. Bazhenov, V.A. Khomich, V.M. Piun // Вопросы атомной науки и техники. — 2010. — № 4. — С. 234-239. — Бібліогр.: 12 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/17337 Influence of air and water molecules detached from the chamber walls under ion impacts on UV radiation from hollow cathode discharge plasma in oxygen, nitrogen, and air is studied. Dependencies of UV radiation intensity and dose on the discharge glow duration, working gas type and pressure, and the discharge power are determined. Исследовано влияние примесей молекул воздуха и воды, оторванных от стенок камеры под действием ионных ударов, на УФ-излучение плазмы разряда с полым катодом на кислороде, азоте и воздухе. Установлены зависимости интенсивности и дозы УФ-излучения от длительности горения разряда, вида рабочего газа, его давления и мощности в разряде. Досліджено вплив домішок молекул повітря та води, відірваних зі стінок камери під впливом іонних ударів, на УФ-випромінювання плазми розряду з порожнистим катодом на кисні, азоті та повітрі. Встановлено залежності інтенсивності та дози УФ-випромінювання від тривалості горіння розряду, виду робочого газу, його тиску та потужності в розряді. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Плазменно-пучковый разряд, газовый разряд и плазмохимия Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles Особенности ультрафиолетового излучения плазмы разряда с полым катодом, используемого для стерилизации медицинских изделий Особливості ультрафіолетового випромінювання плазми розряду з порожнистим катодом, що використовується для стерилізації медичних виробів Article published earlier |
| spellingShingle | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles Tsiolko, V.V. Bazhenov, V.Yu. Khomich, V.A. Piun, V.M. Плазменно-пучковый разряд, газовый разряд и плазмохимия |
| title | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| title_alt | Особенности ультрафиолетового излучения плазмы разряда с полым катодом, используемого для стерилизации медицинских изделий Особливості ультрафіолетового випромінювання плазми розряду з порожнистим катодом, що використовується для стерилізації медичних виробів |
| title_full | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| title_fullStr | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| title_full_unstemmed | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| title_short | Peculiarities of UV radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| title_sort | peculiarities of uv radiation from hollow cathode discharge plasma used for sterilization of medical articles |
| topic | Плазменно-пучковый разряд, газовый разряд и плазмохимия |
| topic_facet | Плазменно-пучковый разряд, газовый разряд и плазмохимия |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/17337 |
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