94077 Referee Report

Discharge Characteristic of Gliding Arc in Chlorinated Methanes

插入: s

Antonius Indarto Korea Institute of Science & Technology, Clean Technology Research Center,

插入: Clean Technology Research Center,

P.O. Box 131, Cheongryang, Seoul 130-650, Korea

Abstract- The plasma discharge characteristics of chloromethane compounds (methylene chloride (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4)) diluted in atmospheric air using a gliding arc has been studied. The variation of injected

插入: using a gliding arc

initial chloromethane concentrations, total gas flow rates, and power frequency were applied as the experimental variables to investigate the discharge behaviors. This paper

插入: varied 插入: parameters

evaluates the plasma process phenomena of chloromethane by gliding arc plasma.

Key words: Plasma, Gliding Arc, chloromethane, AC wave form, equilibrium voltage,

插入: discharge

插入: gas flow rate 插入: frequency dependence

voltage breakdown 註解 [KCC1]: More reference s needed.

1. Introduction

插入: d 插入: method

The applications of gliding arc for destructing toxic materials, such as: H2S [1], N2O[2], CHCl3 and CCl4 [3-4], have been investigate and used widely now. Usually, high percentage of destruction efficiency could be achieved using this method.

插入: first 插入: between 插入: then 插入: along the gap opening

The gliding arc creates arcs at the shortest distance the electrodes and arcs move together with gas flow at the same direction. The number of produced arc is dependent on many factors, such as: frequency of the power supply, flowing gas, and total gas flow

插入: s each cycle 註解 [KCC2]: Give all import ant factors, not just those stud ied in this paper.

rate. During this movement, plasma reaction is occurred simultaneously. Plasma arc usually has a powerful energy to destruct strong molecule-bond or initiate the reaction

插入: high 插入: adequate

of stable gas material due to higher flame temperature and higher electron density. Theoretical and numerical study of gliding arc has been published with showing many mathematical equations [5-9]. However, not many papers discuss on the discharge behavior of gliding arc plasma. In this paper, the physical plasma characteristic of chloromethane compounds diluted in compressed air was tried to be explained. The

插入: ar 插入: s 註解 [KCC3]: I don＇t know what you mean here. 註解 [KCC4]: Not good com ment on these theoretical studi

experiment was carried out with two triangular stainless steel electrodes which were

es. Please be more specific.

electrically charged by an AC power supply. According to EPA report, chloromethanes

註解 [KCC5]: Even not many, please give their references a

have been classified as high thermal stability compounds and difficult to be destructed

nd summarize their works.

[10]. The analysis was focusing on discharge phenomena, such as: equilibrium voltage,

插入: gliding arc

breakdown voltage, and voltage-current-power (V-I-W) profile as the influence of

插入: s

various concentrations of chloromethanes, total gas flow rates, and power frequencies.

註解 [KCC6]: Does not matc h the context of this paragrap h. This sentence could be wit h another paragraph describing

2. Experiment setup

why the destruction of chlor omethane is important.

The schematic diagram of experimental setup is shown in Fig.1. Chloromethane

插入: function

compounds and atmospheric air were mixed and used as the source gas. Details of each

插入: al

part of the system are described in the next section.

2.1. Plasma reactor and applied power system Figure 1

The reactor was made from a quartz-glass tube with inner diameter of 45 mm and length

of 300 mm. The upper part and bottom of the reactor supplied with a teflon seal

插入: ends 插入: were

comprised two electrodes made of stainless steel. The length of the electrodes was 150 mm long. The gap separation of the electrodes in the narrowest section was only 1.5 mm. The gas mixture was introduced between the electrodes through a capillary (nozzle tube) with inner diameter of 0.8 mm. A thermocouple, located 10 cm above the electrode, has been provided to measure the outlet gas temperature. A high frequency AC power supply (Auto electric, A1831) with a maximum voltage of 10 kV and a maximum ampere of 100 mA was connected to the electrodes to generate plasma. The

插入: respectively, 註解 [KCC7]: The electrode material, thickness, opening sl ope or gradient, etc., are also interesting parameters. 插入: and the the bottom one is 插入: of 插入: triangular-shaped

frequency could be adjusted from 10 to 20 kHz. 插入: s

2.2. Input gas

Chlorinated methanes, as the starting material, are:

插入: used 插入: in this work

a. Methylene chloride: CH2Cl2, molecular weight 84.93, purity 99.0%, purchased from Junsei Chemical Co., Ltd., concentration 1, 2, 3, 4 % volume/volume

插入: s 插入: and

b. Chloroform: CHCl3, molecular weight 119.38, purity 99.0%, purchased from Junsei Chemical Co., Ltd., concentration 1, 3, 5, 8% v/v.

插入: s 插入: and

c. Carbon tetrachloride: CCl4, molecular weight 153.82, purity 99.5%, purchased from Kanto Chemical Co., Inc., concentration 1, 3, 5, 8% v/v.

插入: s 插入: and

Atmospheric air was used as the carrier gas and controlled by a calibrated mass flow controller (Tylan, FC-280S). The flow rates were 3, 4, and 5 Nl/min. Before entering the reactor, atmospheric air was passed through a scrubber first and directly mixed with chloromethane compound. The chloromethane compounds were introduced by syringe pump (KD Scientific, Model 100). Heater tape has been attached surrounding the line

註解 [KCC8]: Not shown in the figure. What is its use for the intake gas?

stream to maintain the input stream temperature higher than vaporized temperature of

插入: feed line 插入: the

compounds.

插入: ation

2.3. Measurement system

The supplied power and AC voltage-current (V-I) wave form were measured by a digital oscilloscope (Agilent 54641A) having analog bandwidth of 350 MHz through a high voltage probe (Tektronix P6015A) and current monitor (Pearson 4997). The 註解 [KCC9]: Integration over

consumed power was also calculated by a watt meter (Metex M-3860M). The

功能變數代碼變更

oscilloscope value is the real power used in the reactor only and defined as:

Discharge power = ∫ (V (t ) × I (t ) )dt × frequency Watt

period T: ∫T

插入: experimental data

(1)

插入: after

In this study, each data of experiment was taken after 30 minutes from the start of

插入: ,

gliding plasma operation refers to the stability of bulk gas outlet temperature which has

插入: when 插入: has reached stability

been measured by thermocouple.

插入: s 插入: s

3. Result and Discussion

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3.1. Characteristic of Power Supplies Figure 2

插入: the 插入: y 註解 [KCC10]: I don＇t kno

Figure 3

w what you mean. 註解 [KCC11]: Please defines

The special characteristic of gliding arc is the initial breakdown of the moving gas will begin the cycle of the gliding arc production. The value of initial breakdown voltage is

omewhere the equilibrium volt age and the initial breakdown voltage.

higher than equilibrium voltage. Figure 2 shows the arc movement along the electrode plates. The number of produced arcs could be easily detectedfrom the equilibrium

插入: each vycle 插入: counted

waveform of the voltage and current. As shown in Figure 3, arcs were produced by over-current condition. In this study, the applied AC power supply voltage and current

插入: equilibrium 註解 [KCC12]: I don＇t kno w what you mean.

were determined itself by plasma system. After reaching initial breakdown, power

註解 [KCC13]: Together with?

voltage and current decreased into equilibrium state which could not be adjusted or

插入: the applied

changed by power supply controller. Power supply frequency was the only adjustable

插入: an

independent variable in this experiment. Frequency gave an important role in the

插入: plays 插入: in each cycle

number of arcs production.

3.1. Influence of chloromethane compounds Figure 4

Figure 5

Consumed or applied power is the main important factor to adjust the stability or in-

註解 [KCC14]: These two ar e different things. ?

stability of gliding plasma. Although the concentration and flow rate were kept constant

插入: ,

but difference compounds of injected material gave different power consumption.

插入: t

Figure 4 shows the comparison of oscilloscope result of average voltage. Small different

插入: s

of voltage area and maximum peak voltage were found. With increasing concentration

插入: s

of chloromethane in inlet stream, the difference values of those variables were getting

插入: ces 插入: in

higher. It is shown clearly in figure 5. From figure 5, it can be concluded that CCl4 consumes highest discharge power. The total consumed discharged power follows:

插入: as 插入: the

CCl4 > CH2Cl2 > CHCl3

插入: the order

A match analytical explanation could be found following the Paschen’s Law where the

插入: ing

potential is a function of pressure and gap length [11].

插入: breakdown

V = f ( p, d )

(2)

功能變數代碼變更

In this experiment, the gap distance of electrode was kept constant and the pressure could be assumed constant also. Although it was mainly function of p and d, in the real experiment, some coefficient must be added to match the result between experiment and

插入: S 插入: other

mathematical calculation [12]. Extended of equation Eq. 1 gives: V=

B pd ⎡ A pd ⎤ ln ⎢ ⎥ ⎣ ln(1 / γ ) ⎦

插入: s

(3)

功能變數代碼變更 插入: coefficient

γ is secondary emission of electron of Townsend and followed: 1

γ

=∈αd

插入: Refinement

(4)

註解 [KCC15]: Exponential s ymbol 功能變數代碼變更

Differentiating Eq. 2 and set the derivation equal to zero will give: ( pd ) m =

e 1 2.718 1 ln = ln γ A γ A

插入: 3

(5)

功能變數代碼變更

The minimum or maximum voltage was obtained by substituting Eq. 5 into Eq. 3: Vm = 2.718

B 1 ln A γ

(6)

Eq. 6 is usually called as voltage of breakdown (Vbd). In case gliding arc, Vm > V. Less

功能變數代碼變更

插入: the 插入: of

information about constant of A and B under gliding arc plasma. The parameters A and B must be experimentally determined [13].

插入: There are l 插入: for

Routing Eq. 3 and 6, it could be said there is a relation of V to the Vbd. Experiment result got the different value of Vbd when the chloromethane compounds were injected in the different ratio of concentration. In this study, to prove the relationship of V and Vbd, the algorithm followed this way:

註解 [KCC16]: Does not mat ch the context. 插入: derive

By re-arrangement of Eq. (6) into: A=

2.718 1 B ln γ Vm

and substituting into Eq. (3) will give:

(7)

功能變數代碼變更

功能變數代碼變更

V=

B pd

(8)

⎡ 2.718 B ⎤ ln ⎢ ⎥ ⎣ Vm ⎦

If we compare two different amount of concentration of chloromethane compounds:

插入: s 功能變數代碼變更

B1 p1 d 1 ⎡ 2.718 B1 ⎤ ln ⎢ ⎥ V m1 ⎦ V1 ⎣ = B2 p 2 d 2 V2 ⎡ 2.718 B2 ⎤ ln ⎢ ⎥ ⎣ Vm 2 ⎦

(9)

The experiment was occurred at the same condition of pressure and gap distance and it can be written: p1 = p2 and d1 = d2. Parameter B is function of effective ionization (V*) and pressure. This potential will be used to travel the electron through the gap to make ionization. Because we used the same gap distance, pressure, and very low concentration different of chloromethane compounds, it could be assumed that B1 ≈ B2.

插入: ce

The remaining Eq. (9) will be: 註解 [KCC17]: The suffixes

⎛1⎞ ln⎜⎜ ⎟⎟ ⎝ V1 ⎠ = Vm 2 ⎛ 1 ⎞ Vm1 ln⎜⎜ ⎟⎟ ⎝ V2 ⎠

are wrong?

(10)

LH 1->1m, 2->2

m; RH 1m->1, 2m->2. 功能變數代碼變更

Figure 6

The comparison between calculation and experimental result is shown in Fig. 6. When the experiment was done with concentration as the variable but at same compound of chloromethanes, the result was closed each other. The satisfaction result was also

插入: for the 插入: to 插入: ory

achieved when the experiment has been done in the different total gas flow rate and fixed amount of concentration and chloromethane species. However, this kind of result

插入: the case of 插入: the

could not be found when we applied same flow rate in different compound of

插入: the 插入: to

chloromethane. It means that the parameters A and C have specific number for each chloromethane gases and give the important role to initiate the production of arc in

插入: B 插入: values

gliding system.

插入: play

Radu, et.al. and others have studied and mentioned about the effect of electron on

插入: s

breakdown initiation. Lack of free electrons, those are necessary to initiate a breakdown

插入: in

under ac condition, will lead to over-voltage across the short gap that will produce larger magnitude and more rapid rise times [14-17]. Taylor et al. compared the stability

插入: ing 插入: [14-17] 插入: which

of these compounds and gave the order of stability under oxidative condition [18]: CCl4 = CH2Cl2 > CHCl3

插入: [18] 註解 [KCC18]: ????

And in the absence of oxygen: CCl4 > CH2Cl2 > CHCl3 Stability depends on the structure and the chemical-bond of compounds. This factor

插入: 插入: the

could tell the reason why CCl4 gives the highest value of V and Vbd. This result is also match with other experiment result which CCl4 produced a higher energy consumption

插入: ed 插入: al

than CHCl3 [4].

插入: in

3.2. Influence of total gas flow rate Figure 7

Un-adjustable equilibrium voltage and current by power supply controller after initial breakdown made the experiment little bit difficult to set in the exact same supplied voltage and current. In this case, the total gas flow rate was also a factor that must be counted as a variable. Fig. 7 shows the effect of total gas flow rate on power profile. By

插入: a 註解 [KCC19]: Do you mean “to keep constant the suppli ed voltage and current from r un to run＂? 插入: the

comparing, it could be easily that at 3 Nl/min, total discharge power that supplied to the

插入: son 插入: observed

system has the higher value compared to 4 and 5 Nl/min.

Figure 8

To study deeply about this effect, we have tried to capture the real voltage-current profile at equilibrium condition. Fig. 8 shows the behavior of voltage-current wave. Calculation of both real and average value of voltage wave gave the result that total

插入: the 插入: those at

插入: into 插入: form 註解 [KCC20]: Please define real and average values

supplied voltage would be lower at lower total gas flow rate. But, the different was not

插入: ce

significantly high. This phenomenon has clearly explained by previous explanation of

插入: been

Paschen’s law [12]. Usually increasing flow rate would increase the pressure to the system. Increasing pressure could increase the breakdown-voltage (Vb) in term of producing initial arc and equilibrium voltage in term of stabilizing arc cycle production. Current wave form effect could be suspected as the main reason of the increasing or decreasing value of total discharge power. Comparing fig 8 (b), (d), and (e), it shows that at 3 Nl/min the number of sudden-fluctuated pulse was higher that two others. It

插入: current waveforms in 插入: spike 插入: n

means at 3 Nl/min the system produced higher number of arc compared to 4 and 5 Nl/min. As mention before, as effect of increasing flow rate refers to increasing pressure,

插入: those of the other two 插入: s

the possibility to produce arc was getting decrease. That is why the number of sudden-

插入: the

fluctuated pulse was lower and lower with the increment of total gas flow rate. However,

插入: d

sudden-fluctuated pulses also gave significant contribution to the calculation of average

插入: spike

total supply current to the system. Compared to average current when plasma was off, the value of total average current when plasma on was 5 ~ 10 times higher.

3.3. Effect of frequency

插入: spike 插入: was

Figure 9

Figure 10

Power supply frequency was adjustable factor in this experiment. Fig. 9 shows the

插入: an

effect of frequency on power profile. Integration calculation by Eq. 1 gave the total discharge power increased linier with increasing number of frequency. When the

插入: early 插入: , Fig. 10

condition was kept constant, number of arc was also increased. Radu et. al. mentioned that changing the frequency will change the basic Townsend breakdown mechanism

插入: s 插入: [14]

[14]. Increasing frequency would increase the number of sudden-fluctuated pulsed current and voltage peak per cycle. Examined the power waveform, increasing number

插入: spikes of

of peak per cycle would give more supply of energy, Fig. 10. Measurement using wattmeter was also giving the same trend as oscilloscope measurement but little bit

插入: gave 插入: a

higher. Oscilloscope just measured the netto energy that was supplied to the plasma system. In the other hand, wattmeter measured the total power that needed by all instrument, including total power to operate the power supply.

插入: O 插入: 插入: the

4. Conclusion

插入: s 插入: ations of 插入: discharge

The power discharge characteristic of gliding arc plasma using chloromethane

插入: ,

compounds has been studied. Various concentration, total gas flow rate, and frequency

插入: , and

have been used to investigate the behavior of voltage-current-power (V-I-W). Different

插入: s

kind of chloromethane compounds gave significant different value of discharge power,

插入: ly

equilibrium voltage, and breakdown voltage also which CCl4 gave the highest value of

插入: s

them. In case of different concentration and total gas flow rate, the phenomena were

插入: , in 插入: shows

following Paschen’s law which gave relation between equilibrium voltage and

插入: followed 插入: a

breakdown voltage. Increasing amount of total gas flow rate would degrease the discharge power. It would reduce the number of production of arc that would reduce the

插入: ship 插入: the

sudden-fluctuated pulse in the current wave. Discharge power would also increase with

插入: c

the increasing value of frequency.

插入: arc 插入: ,

Acknowledgement

插入: is, 插入: number of 插入: spike

This work was supported by the National Research Laboratory program of the Korea Minister of Science and Technology.

插入: increasing 插入: ry

References

[1]

V. Dalaine, J. M. Cormier, and P. Lefaucheux, J. Appl. Phys., 83 (5), 2435 (1998)

[2]

K. Krawczyk and M. Mlotek, Appl. Catal., 30, 233 (2001)

[3]

K. Krawczyk and B. Ulejczyk, Plasma Chem. Plasma Process., 23 (2), 256, 2003.

[4]

K. Krawczyk and B. Ulejczyk, Plasma Chem. Plasma Process., 24 (2), 155, 2004.

[5]

A. Fridman, S. Nester, L. A. Kennedy, A. Saveliev, O. M. Yardimci, Prog. Energy Combust. Sci., 25, 211 (1999)

[6]

O. M-Yardimci, A. V. Saveliev, A. A. Fridman, and L. A. Kendedy, J. Appl. Phys., 87 (4), 1632 (2000)

[7]

I. V. Kuznetsova, N. Y. Kalashnikov, A. F. Gutsol, A. A. Fridman, and L. A. Kennedy, J. Appl. Phys., 92 (8), 4231 (2002)

[8]

F. Richard, J. M. Cormier, S. Pellerin, and J. Chapelle, J. Appl. Phys. 79 (5), 2245

插入: 265

(1996) [9]

S. Pellerien, F. Richard, J. Chapelle, J-M Cornier, and K Musiol, J. Phys. D: Appl. Phys., 33, 2407 (2000)

[10] P. H. Taylor, B. Dellinger, C. C. Lee, Environ. Sci. Technol. 24(3), 316 (1990). [11] v. F. Paschen, Wied. Ann, 37, 69 (1889). [12] J. D. Cobine, Gaseous Conductor Theory and Engineering Application (Dover Publications, Inc., 1958), pp. 160-177 [13] J. R. Roth, Industrial Plasma Engineering Volume 1: Principles (Institute of Physic Publishing, 1995), pp.237-256. [14] I. Radu, R. Bartnikas, and M. R. Wertheimer, IEEE Trans. Plasma Sci., 31 (6), 1363 (2003) [15] R. Bartnikas, IEEE Trans. Dielect. Elect. Insulation, 9, 763 (2002) [16] J. P. Novak and R. Barnitas, J. Appl. Phys., 62 (9), 3605 (1987) [17] R. Barnitas and J. P. Novak, IEEE Trans. Dielect. Elect. Insulation, 2 (4), 557 (1995) [18] P. H. Taylor and B. Dellinger, Environ. Sci. Technol., 22 (4), 438 (1988)

格式化: 字型: 非斜體, (符號) Times New Roman, 中東文 字字型: 非斜體

to analysis instrument electricity

power meter

termocouple 10 cm

Plasma Reactor AC power supply temperatur recorder

oscilloscope

nozzle tube syringe heater tape Compressed air

MFC

Fig. 1. Schematic diagram of experimental set up

插入: the

Figure 2. Gliding Arc movement along the electrode plate. Captured by high-speed camera

插入: a 插入: , c

6000

4000

voltage (V)

2000

0

-2000

-4000

-6000 0.4

current (A)

0.2

breakdown arc

0.0

-0.2

-0.4

插入: s

-0.6 -2e-5

-1e-5

0

1e-5

2e-5

time (s)

插入: the 插入: discharge 註解 [KCC21]: It is suggeste

Figure 3. Typical waveform of AC power supply. The arc production phenomena could be seen clearly

d that the time in unit of mic rosecond and the x-ais labeled

from fluctuation of current wave form.

by -20 to 20 in step of 10. The y-axis in kV labeled fro m -6 to 6 in steps of 2. 插入: the 插入: spikes

4000 3000

Voltage (V)

2000 1000 0 -1000 CH2Cl2

-2000

CCl4 CHCl3

-3000

air -4000 -2e-5

-1e-5

0

1e-5

2e-5

time (sec) Fig 4. Voltage profile

註解 [KCC22]: It is suggeste d that the time in unit of mic rosecond and the x-ais labeled by -20 to 20 in step of 10. The y-axis in kV labeled fro m -4 to 4 in steps of 1.

插入: s of gliding arc discharges with various gas mixtures

250

Dischrage power (Watt)

240 230 220 210 CCl4, 3 Nl/min

200

CCl4, 4 Nl/min CCl4, 5 Nl/min

190

CHCl3, 3 Nl/min CHCl3, 4 Nl/min

180

CHCl3, 5 Nl/min CH2Cl2, 3 Nl/min

170 0

1

CH2Cl2, 4 Nl/min 2 3

4

5

6

7

8

9

Concentration (% v/v)

Figure 5. Effect of injected chloromethane compounds (species, concentration, and total gas flow rate) on discharge power

8

Vbd (kV)

7

6

5 3 Nl/min, calculation 4 Nl/min, calculation 5 Nl/min, calculation CCl4, experiment

4

CHCl3, experiment CH2Cl2, experiment 3 0

2

4

6

8

10

Concentration (% v/v) Figure 6. Comparison of calculated and experimental value of Vbd.

註解 [KCC23]: There are mo re lines and symbols in the fi gure than those shown in the caption. Please add more desc ription, maybe, like in Fig. 5 插入: s

1000 3 Nl/min 4 Nl/min 5 Nl/min

800

Power (Watt)

600

400

200

0

-200 -2e-5

-1e-5

0

1e-5

2e-5

Time (sec) Figure 7 Power profile as effect of total gas flow rate. Data was taken using 1% of CCl4 as injected compound and power frequency 20 kHz.

插入: the function 註解 [KCC24]: It is suggeste d that the time in unit of mic rosecond and the x-ais labeled by -20 to 20 in step of 10.

3000

2.0

2000

1.5

1.0

Current (A)

Voltage (V)

1000

0

0.5

0.0

-1000 -0.5 -2000

-1.0

-3000

-1.5 -2e-5

-1e-5

0

1e-5

2e-5

-2e-5

-1e-5

Time (sec)

(a)

1e-5

2e-5

1e-5

2e-5

(b)

3000

2.0

2000

1.5

1.0

Current (A)

1000

Voltage (V)

0

Time (sec)

0

0.5

0.0

-1000 -0.5 -2000

-1.0

-3000

-1.5 -2e-5

-1e-5

0

1e-5

2e-5

-2e-5

-1e-5

Time (sec)

(c)

(d)

3000

2.0

2000

1.5

1.0

Current (A)

1000

Voltage (V)

0

Time (sec)

0

0.5

插入: ,

0.0

註解 [KCC25]: It is suggeste

-1000 -0.5 -2000

d that the time in unit of mic

-1.0

-3000

rosecond and the x-ais labeled

-1.5 -2e-5

-1e-5

0

1e-5

2e-5

-2e-5

-1e-5

0

Time (sec)

Time (sec)

(e)

(f)

1e-5

2e-5

Figure 8. Voltage-Current behavior at 1% of injected CCl4, power frequency 20 kHz. (a) V-3 Nl/min (b) I3 Nl/min (c) V-4 Nl/min (d) I-4 Nl/min (e) V-5 Nl/min (f) I-5 Nl/min

by -20 to 20 in step of 10. The y-axis in kV labeled fro m -3 to 3 in steps of 1. And V and I are grouped as one sub-figure. 插入: b 插入: , 插入: c 插入: .

1000 15 kHz 16.25 kHz 17.5 kHz 18.75 kHz 20 kHz

800

Power (Watt)

600

400

200

0

-200 -2e-5

-1e-5

0

1e-5

2e-5

Time (sec)

Fig 9. Effect of applied power supply frequency on power profile. Data was taken using 10% of CHCl3 at total gas flow rate 2.5 Nl/min

註解 [KCC26]: It is suggeste d that the time in unit of mic rosecond and the x-ais labeled in step of 10. It is suggested that a COMPLETE cycle is shown for each and every fre quency. The time range in the present figure is not wide en ough.

插入: .

340

Discharge power (Watt)

320 300 280 260 240 220 Wattmeter Oscilloscope

200 180 14

15

16

17

18

19

20

21

Time (sec)

Fig 10. Effect of applied power supply frequency on total discharge power. Data was taken using 8% of CHCl3 at total gas flow rate 2.5 Nl/min

註解 [KCC27]: The x-axis is labeled wrong. It should be fr equency (kHz) instead of tim e. 插入: .