22P084
Ejection frequency of spallation particles from polymers during irradiation ofAr thermal plasmas with diﬀerent molecular gases.
各種ガス系の混合 Ar 誘導熱プラズマ照射におけるスポレーション粒子の飛翔頻度
Naoki Shinsei, Masahiro Ishida, Yasunori Tanaka,Yoshihiko Uesugi
Junichi Wada and Shigemitsu Okabe
新清直樹, 石田昌弘, 田中康規, 上杉喜彦
和田純一，岡部成光
Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
金沢大学 〒 920-1192 金沢市角間町
In this report, we estimated ejection frequency of spallation particles during irradiation of Ar thermal plasmas with diﬀerent molecular gases. The arc plasma may contact the polymer materials, inevitably involving polymer ablation. We found out that not only polymer ablated vapor but also spallation particles wereejected from the polyamide materials surface during irradiation of Ar thermal plasma. Many spallation
particle injection can aﬀect the arc plasma through their much ablation.

Introduction
Gas
Sheath gas
injection
Polymer materials are widely used for insulator in(Ar)RF Coil Polymer bulk
8 turnlow-voltage circuit breakers, and for gas flow nozzle
70 mmφ14mm 15 mmφ
high-voltage circuit breakers. In a current interruption
155 mm
345 mm(fromendprocess, the arc plasma is formed between the electo end)
5 mmtrodes in the circuit breaker. The arc plasma may con200 mm
Sample holder
tact the polymer materials, inevitably involving polyPolymer bulk
High-speed color video
mer ablation. Eﬀective utilization of such polymer ablation is expected to enhance the arc interrupting capaMovablespecimenbility of the circuit breaker.
holderIn our previous works, we found out that not only
polymer ablated vapor but also spallation particles were Fig. 1: RF plasma torch and high-speed video camera.
ejected from the polyamide materials surface during steel is located. A color high-speed video camera wasirradiation of Ar thermal plasma [1]. Many spallation used to observe polymer ablated vapor near the polyparticle injection can aﬀect the arc discharge further mer surface from the observation window. The experthrough much ablation inside the arc plasma. This imental condition was as follows: The gas flow ratereport describes experimental results of Ar+N2 and was set to Ar:30 slpm in case of 100%Ar, Ar:50 slpm
Ar+O2 plasma irradiation to polymer materials. The + N2 :1.5 slpm in case of 97%Ar+3%N2 , and Ar:50
moleculear gas N2 or O2 was added to Ar plasma gas slpm + O2 :2.5 slpm in case of 95%Ar+5%O2 . The
to study their eﬀects on the spallation production. Ejec- input power to the thermal plasmas was controlled totion frequency of spallation particles was estimated for equal irradiation heat flux onto the surface of the polyAr, Ar+N2 and Ar+O2 plasmas irradiation.
mer specimen for any gas conditions. The pressure
inside the chamber was 760 torr. The frame rate of the2. Experimental setup and conditions
Fig. 1 shows the plasma torch, the specimen holder video recording was 1000 fps. Three kinds of polyand the observation system used in this experiment. mer materials were used as a specimen; PTFE (polyteThe torch is 345 mm long, and 70 mmϕ in inner di- trafluoroethylene) [-C2 F4 -]n , PA66 (polyamide-66) [ameter. From the top of the torch, Ar gas is supplied C12 H22 O2 N2 -]n and PA6 (polyamide-6) [-C6 H11 ONalong the wall as a sheath gas. Around the torch, an ]n . The diameter and the thickness of the cylindricaleight-turn induction coil is located to generate electro- polymer specimen used here are 15 mmϕ and 5 mm,
magnetic field inside the torch. This electromagnetic respectively.
field then generates a thermal plasma inside the plasma 3. Results and discussions
torch. A reaction chamber is installed downstream of 3.1. High-speed video camera observation results
the plasma torch. Inside the reaction chamber, a movA color high-speed video camera was used to obable water-cooled specimen holder made of stainless serve polymer ablated vapor near the polymer surface
1.

(a) PTFE(b) PA66(c) PA6Fig. 2: Ablated vapor and spallation particles in caseof Ar induction thermal plasma irradiation.

]-[10slecit 8rap
no 6tiala
ps 4fore 2bm
uN00100%Ar
5 mm above the surface
PA66

600
500
400300200-][muS

1000400
600
800
1000
Time [ms](a) Irradiation of Ar thermal plasma.
600-][10 97%Ar+3%N200sel 5 mm above the surface
cti 8 PA66
rap
no 6itla
ap 4sforeb 2m
uN00200
4006002(a) PTFE(b) PA66(c) PA6Fig. 3: Ablated vapor and spallation particles in caseof Ar+N2 induction thermal plasma irradiation.

500400]-[mu200 S
300
1000800
1000
Time [ms](b) Irradiation of Ar+N2 thermal plasma.
][-10600eslc 95%Ar+5%O
mm above the surface
it 8 5PA66
rap
no 6tiala
ps 4fore 2bm
uN00200
4006002(a) PTFE(b) PA66(c) PA6Fig. 4: Ablated vapor and spallation particles in caseof Ar+O2 induction thermal plasma irradiation.

500400300200100-][muS

during irradiation of the Ar, Ar+N2 and Ar+O2 in0
duction thermal plasmas. Figs. 2–4 present cumula800
1000
Time [ms]tive images to show the trajectories of spallation par(c) Irradiation of Ar+O2 thermal plasma.
ticles ejected from polymer materials. These figures
Fig.
5:
Number of spallation particles(PA66)
were produced by combining 100 consecutive imagesof high-speed video camera. In case of PTFE irradiated Ar or Ar+N2 thermal plasma, only ablated va- cles were totally found to fly in 1000 ms. Therefore,
por cloud can be strongly seen near the surface of the the mean ejection frequency of the spallation particles
PTFE specimen. The blue or blue-violet light are stronglycan be estimated about 2.4 ms in Ar+O2 plasma irraobserved from the polymer ablated vapors. This may diation.
be due to C2 or CN molecular spectra originating from 4. Conclusion
the polymer vapors. On the other hand, in cases ofIn this report, we investigated a dynamics behavPA66 and PA6, spallation particles ejected from spec- ior of spallation particles from polymers during irraimens can be found definitely. These particles were diation of Ar thermal plasmas with diﬀerent molecuobviously found flying from the specimen surface to lar gases. As a result, spallation particles also were25 mm or above against the eath gases flow from the ejected from polyamide materials in case of Ar+N2
upstream to the specimen surface.
and Ar+O2 thermal plasmas irradiation. These par3.2. Ejection frequency of spallation particles
ticles were found flying from the specimen surface toWe estimated how often particles were ejected from 25 mm or above against the eath gases flow from thethe specimen. The bar chart in Fig. 5 shows the num- upstream to the specimen surface. In case of Ar+O2
ber of particles ejected from PA66 surface in 1000 ms thermal plasma irradiation, the most number of spalduring the irradiation of each thermal plasma. This lation particles were ejected from PA66 surface, andfigure also includes their accumulative number of the thus about 470 particles were totally found to fly inparticles, which refers to the right vertical axis. As 1000 ms.
seen in this figure, spallation particles were ejected al- References
most constantly. In case of Ar+O2 thermal plasma ir- [1] Y.Tanaka et al., “Spallation particle ejection fromradiation, the most number of spallation particles werepolymer surface irradiated by thermal plasmas”,
ejected from PA66 surface, and thus about 470 partiIEEE Trans. Plasma Sci, 2011(to appear)