Properties of temporal X-ray in nanosecond-pulse discharges with a tube-to-plane gap at atmospheric pressure

Hou Xing-Min; Zhang Cheng; Qiu Jin-Tao; Gu Jian-Wei; Wang Rui-Xue; Shao Tao

doi:10.7498/aps.66.105204

Abstract

Nanosecond-pulse discharge can produce low-temperature plasma with high electron energy and power density in atmospheric air, thus it has been widely used in the fields of biomedical science, surface treatment, chemical deposition, flow control, plasma combustion and gas diode. However, some phenomena in nanosecond-pulse discharge cannot be explained by traditional discharge theories (Townsend theory and streamer theory), thus the mechanism of pulsed gas discharge based on runaway breakdown of high-energy electrons has been proposed. Generally, the generation and propagation of runaway electrons are accompanied by the generation of X-ray. Therefore, the properties of X-ray can indirectly reveal the characteristics of high-energy runaway electrons in nanosecond-pulse discharges. In this paper, in order to explore the characteristics of runaway electrons and the mechanism of nanosecond-pulse discharge, the temporal properties of X-ray in nanosecond-pulse discharge are investigated. A nanosecond power supply VPG-30-200 (with peak voltage 0200 kV, rising time 1.2-1.6 ns, and full width at half maximum 3-5 ns) is used to produce nanosecond-pulse discharge. The discharge is generated in a tube-to-plane electrode at atmospheric pressure. Effects of the inter-electrode gap, anode thickness and position on the characteristics of X-ray are investigated by measuring the temporal X-ray via a diamond photoconductive device. The experimental results show that X-ray in nanosecond-pulse discharge has a rising time of 1 ns, a pulse width of about 2 ns and a calculated energy of about 2.310-3 J. The detected X-ray energy decreases with the increase of inter-electrode gap, because the longer discharge gap reduces the electric field and the number of runaway electrons, weakening the bremsstrahlung at the anode. When the inter-electrode gap is 50 mm, the discharge mode is converted from a diffuse into a corona, resulting in a rapid decrease in X-ray energy. Furthermore, both X-ray energies measured behind the anode and on the side of discharge chamber decrease as anode thickness increases. The X-ray energy measured on the side of the discharge chamber is one order of magnitude higher than that measured behind the anode, which is because the anode foil absorbs some X-rays when they cross the foil. In addition, the X-ray energy behind the anode significantly decreases with the increase of the thickness of anode aluminum foil. It indicates that the X-ray in nanosecond-pulse discharge mainly comes from the bremsstrahlung caused by the collision between the high-energy runaway electrons and inner surface of the anode foil. Therefore, increasing the thickness of the anode foil will reduce the X-ray energy across the anode film.

Keywords:

Authors and contacts

1.
Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
2.
University of Chinese Academy of Sciences, Beijing 100039, China;
3.
China Electric Power Research Institute, Beijing 100192, China

Corresponding author: Zhang Cheng, zhangcheng@mail.iee.ac.cn;st@mail.iee.ac.cn ; Shao Tao, zhangcheng@mail.iee.ac.cn;st@mail.iee.ac.cn

Funds: Project supported by the National Natural Science Foundation of China (Grant Nos. 51477164, 11611530681), and State Key Laboratory of Alternate Electrical Power System, China (Grant No. LAPS16013).

References

[1]	Shao T, Zhang C, Wang R X, Yan P, Ren C Y 2016 High Volt. Eng. 42 685 (in Chinese) [邵涛, 章程, 王瑞雪, 严萍, 任成燕 2016 高电压技术 42 685]
[2]	Lu X P, Yan P, Ren C S, Shao T 2011 Sci. China: Phys. Mech. Astron. 41 801 (in Chinese) [卢新培, 严萍, 任春生, 邵涛 2011 中国科学:物理学力学天文学 41 801]
[3]	Li Y, Mu H B, Deng J B, Zhang G J, Wang S H 2013 Acta Phys. Sin. 62 134703 (in Chinese) [李元, 穆海宝, 邓军波, 王曙鸿 2013 62 134703]
[4]	Yu J L, He L M, Ding W, Wang Y Q, Du C 2013 Chin. Phys. B 22 055201
[5]	Korolev Y D, Mesyats G A 1998 Physics of Pulsed Breakdown in Gases (Ekaterinburg: URO-Press) pp161-162
[6]	Baksht E H, Burachenko A G, Kostyrya I D, Lomaev M I, Rybka D V, Shulepove M A, Tarasenko V F 2009 J. Phys. D: Appl. Phys. 42 185201
[7]	Zhang C, Shao T, Long K H, Yu Y, Wang J, Zhang D D, Yan P, Zhou Y X 2010 IEEE Plasma Sci. 38 1517
[8]	Chen F, Huo Y J, He S F, Feng L C 2001 Chin. Phys. Lett. 18 228
[9]	Zhang C, Tarasenko V F, Shao T, Beloplotov D V, Lomaev M I, Wang R X, Sorokin D A, Yan P 2015 Phys. Plasmas 22 033511
[10]	Che X K, Nie W S, Zhou P H, He H B, Tian X H, Zhou S Y 2013 Acta Phys. Sin. 62 224702 (in Chinese) [车学科, 聂万胜, 周朋辉, 何浩波, 田希晖, 周思引 2013 62 224702]
[11]	Dai D, Wang Q M, Hao Y B 2013 Acta Phys. Sin. 62 135204 (in Chinese) [戴栋, 王其明, 郝艳捧 2013 62 135204]
[12]	Zhang C, Tarasenko V F, Gu J W, Baksht E K, Beloplotov D V, Burachenko A G, Yan P, Lomaev M I, Shao T 2016 Phys. Rev. Accel. Beams 19 030402
[13]	Wang X Q, Dai D, Hao Y B, Li L C 2012 Acta Phys. Sin. 61 230504 (in Chinese) [王敩青, 戴栋, 郝艳捧, 李立浧 2012 61 230504]
[14]	Mesyats G A, Bychkov Y I, Kremnev V V 1972 Sov. Phys. Usp. 15 282
[15]	Kunhard E E, Tzeng Y 1988 Phys. Rev. A 38 1410
[16]	Babich L P 2005 Phys. -Usp. 48 1015
[17]	Vasilyak L M, Kostyuchenko S V, Kudryavtsev N N, Filyugin I V 1994 Phys. -Usp. 37 247
[18]	Raizer Y P, Allen J E 1991 Gas Discharge Physics (Berlin: Springer-Verlag) pp9-14
[19]	Gurevich A V, Zybin K P 2005 Phys. Today 58 37
[20]	Yakovlenko S I 2007 Proc. Prokhorov General Inst. 63 186
[21]	Noggle R C, Krider E P, Wayland J R 1968 J. Appl. Phys. 39 4746
[22]	Stankevich Y L, Kalinin V G 1968 Sov. Phys. Dokl. 12 1041
[23]	Shao T, Zhang C, Niu Z, Yan P 2011 Appl. Phys. Lett. 98 021503
[24]	Kochkin P, Köhn C, Ebert U, Deursen L V 2016 Plasma Sources Sci. Technol. 25 044002
[25]	Oreshkin E V, Barengolts S A, Chaikovsky S A, Oginov A V, Shpakov K V 2012 Phys. Plasmas 19 013108
[26]	Tarasenko V F, Lomaev M I, Beloplotov D V, Sorokin D A 2016 High Volt. 1 181
[27]	Tarasenko V F, Rybka D V 2016 High Volt. 1 43
[28]	Baksht E K, Burachenko A G, Erofeev M V, Tarasenko V F 2014 Plasma Phys. Rep. 40 404
[29]	Pan L S, Han S, Kania D R, Zhao S, Gan K K, Kagan H, Kass R, Malchow R, Morrow F, Palmer W F, White C, Kim S K, Sannes F, Schnetzer S, Stone R, Thomson G B, Sugimoto Y, Fry A, Kanda S, Olsen S, Franklin M, Ager J W, Pianetta P 1993 J. Appl. Phys. 74 1086
[30]	Spielman R B 1995 Rev. Sci. Instrum. 66 867
[31]	Gu J W, Zhang C, Wang R X, Yan P, Shao T 2016 Plasma Sci. Technol. 18 230
[32]	Shao T, Tarasenko V F, Yang W J, Beloplotov D V, Zhang C, Lomaev M I, Yan P, Sorokin D A 2014 Chin. Phys. Lett. 31 085201
[33]	Zhang R, Luo H Y, Zou X B, Shi H T, Zhu X L, Zhao S, Wang X X, Yap S, Wong C S 2014 IEEE Trans. Plasma Sci. 42 3143
[34]	Shao T, Tarasenko V F, Yang W, Beloplotov D V, Zhang C, Lomaev M I, Yan P, Sorokin D A 2014 Plasma Sources Sci. Technol. 23 054018
[35]	Wang X X 2012 High Volt. Eng. 38 1537 (in Chinese) [王新新 2012 高电压技术 38 1537]
[36]	Zou X B, Wang X X, Zhang G X, Han M, Luo C M 2006 Acta Phys. Sin. 55 1289 (in Chinese) [邹晓兵, 王新新, 张贵新, 韩旻, 罗承沐 2006 55 1289]
[37]	Babich L P, Loiko T V, Tsukernab V A 1990 Sov. Phys. Usp. 33 521
[38]	Gurevich A V, Zybin K P 2001 Phys. -Usp. 44 1119
[39]	Nguyem C V, van Deursen A P J, van Heesch E J M, Winands G J J, Pemen A J M 2010 J. Phys. D: Appl. Phys. 43 025202
[40]	Zhang C, Tarasenko V F, Gu J W, Baksht E, Wang R X, Yan P, Shao T 2015 Phys. Plasmas 22 123516
[41]	Song H M, Jia M, Jin D, Cui W, Wu Y 2016 Chin. Phys. B 25 262
[42]	Wang X B, Li Y D, Cui W Z, Li Y, Zhang H T, Zhang X N, Liu C L 2016 Acta Phys. Sin. 65 047901 (in Chinese) [王新波, 李永东, 崔万照, 李韵, 张洪太, 张小宁, 刘纯亮 2016 65 047901]
[43]	Zhang C, Shao T, Niu Z, Zhang D D, Wang J, Yan P 2012 Acta Phys. Sin. 61 035202 (in Chinese) [章程, 邵涛, 牛铮, 张东东, 王珏, 严萍 2012 61 035202]

Cited By

[1]	Shao T, Zhang C, Wang R X, Yan P, Ren C Y 2016 High Volt. Eng. 42 685 (in Chinese) [邵涛, 章程, 王瑞雪, 严萍, 任成燕 2016 高电压技术 42 685]
[2]	Lu X P, Yan P, Ren C S, Shao T 2011 Sci. China: Phys. Mech. Astron. 41 801 (in Chinese) [卢新培, 严萍, 任春生, 邵涛 2011 中国科学:物理学力学天文学 41 801]
[3]	Li Y, Mu H B, Deng J B, Zhang G J, Wang S H 2013 Acta Phys. Sin. 62 134703 (in Chinese) [李元, 穆海宝, 邓军波, 王曙鸿 2013 62 134703]
[4]	Yu J L, He L M, Ding W, Wang Y Q, Du C 2013 Chin. Phys. B 22 055201
[5]	Korolev Y D, Mesyats G A 1998 Physics of Pulsed Breakdown in Gases (Ekaterinburg: URO-Press) pp161-162
[6]	Baksht E H, Burachenko A G, Kostyrya I D, Lomaev M I, Rybka D V, Shulepove M A, Tarasenko V F 2009 J. Phys. D: Appl. Phys. 42 185201
[7]	Zhang C, Shao T, Long K H, Yu Y, Wang J, Zhang D D, Yan P, Zhou Y X 2010 IEEE Plasma Sci. 38 1517
[8]	Chen F, Huo Y J, He S F, Feng L C 2001 Chin. Phys. Lett. 18 228
[9]	Zhang C, Tarasenko V F, Shao T, Beloplotov D V, Lomaev M I, Wang R X, Sorokin D A, Yan P 2015 Phys. Plasmas 22 033511
[10]	Che X K, Nie W S, Zhou P H, He H B, Tian X H, Zhou S Y 2013 Acta Phys. Sin. 62 224702 (in Chinese) [车学科, 聂万胜, 周朋辉, 何浩波, 田希晖, 周思引 2013 62 224702]
[11]	Dai D, Wang Q M, Hao Y B 2013 Acta Phys. Sin. 62 135204 (in Chinese) [戴栋, 王其明, 郝艳捧 2013 62 135204]
[12]	Zhang C, Tarasenko V F, Gu J W, Baksht E K, Beloplotov D V, Burachenko A G, Yan P, Lomaev M I, Shao T 2016 Phys. Rev. Accel. Beams 19 030402
[13]	Wang X Q, Dai D, Hao Y B, Li L C 2012 Acta Phys. Sin. 61 230504 (in Chinese) [王敩青, 戴栋, 郝艳捧, 李立浧 2012 61 230504]
[14]	Mesyats G A, Bychkov Y I, Kremnev V V 1972 Sov. Phys. Usp. 15 282
[15]	Kunhard E E, Tzeng Y 1988 Phys. Rev. A 38 1410
[16]	Babich L P 2005 Phys. -Usp. 48 1015
[17]	Vasilyak L M, Kostyuchenko S V, Kudryavtsev N N, Filyugin I V 1994 Phys. -Usp. 37 247
[18]	Raizer Y P, Allen J E 1991 Gas Discharge Physics (Berlin: Springer-Verlag) pp9-14
[19]	Gurevich A V, Zybin K P 2005 Phys. Today 58 37
[20]	Yakovlenko S I 2007 Proc. Prokhorov General Inst. 63 186
[21]	Noggle R C, Krider E P, Wayland J R 1968 J. Appl. Phys. 39 4746
[22]	Stankevich Y L, Kalinin V G 1968 Sov. Phys. Dokl. 12 1041
[23]	Shao T, Zhang C, Niu Z, Yan P 2011 Appl. Phys. Lett. 98 021503
[24]	Kochkin P, Köhn C, Ebert U, Deursen L V 2016 Plasma Sources Sci. Technol. 25 044002
[25]	Oreshkin E V, Barengolts S A, Chaikovsky S A, Oginov A V, Shpakov K V 2012 Phys. Plasmas 19 013108
[26]	Tarasenko V F, Lomaev M I, Beloplotov D V, Sorokin D A 2016 High Volt. 1 181
[27]	Tarasenko V F, Rybka D V 2016 High Volt. 1 43
[28]	Baksht E K, Burachenko A G, Erofeev M V, Tarasenko V F 2014 Plasma Phys. Rep. 40 404
[29]	Pan L S, Han S, Kania D R, Zhao S, Gan K K, Kagan H, Kass R, Malchow R, Morrow F, Palmer W F, White C, Kim S K, Sannes F, Schnetzer S, Stone R, Thomson G B, Sugimoto Y, Fry A, Kanda S, Olsen S, Franklin M, Ager J W, Pianetta P 1993 J. Appl. Phys. 74 1086
[30]	Spielman R B 1995 Rev. Sci. Instrum. 66 867
[31]	Gu J W, Zhang C, Wang R X, Yan P, Shao T 2016 Plasma Sci. Technol. 18 230
[32]	Shao T, Tarasenko V F, Yang W J, Beloplotov D V, Zhang C, Lomaev M I, Yan P, Sorokin D A 2014 Chin. Phys. Lett. 31 085201
[33]	Zhang R, Luo H Y, Zou X B, Shi H T, Zhu X L, Zhao S, Wang X X, Yap S, Wong C S 2014 IEEE Trans. Plasma Sci. 42 3143
[34]	Shao T, Tarasenko V F, Yang W, Beloplotov D V, Zhang C, Lomaev M I, Yan P, Sorokin D A 2014 Plasma Sources Sci. Technol. 23 054018
[35]	Wang X X 2012 High Volt. Eng. 38 1537 (in Chinese) [王新新 2012 高电压技术 38 1537]
[36]	Zou X B, Wang X X, Zhang G X, Han M, Luo C M 2006 Acta Phys. Sin. 55 1289 (in Chinese) [邹晓兵, 王新新, 张贵新, 韩旻, 罗承沐 2006 55 1289]
[37]	Babich L P, Loiko T V, Tsukernab V A 1990 Sov. Phys. Usp. 33 521
[38]	Gurevich A V, Zybin K P 2001 Phys. -Usp. 44 1119
[39]	Nguyem C V, van Deursen A P J, van Heesch E J M, Winands G J J, Pemen A J M 2010 J. Phys. D: Appl. Phys. 43 025202
[40]	Zhang C, Tarasenko V F, Gu J W, Baksht E, Wang R X, Yan P, Shao T 2015 Phys. Plasmas 22 123516
[41]	Song H M, Jia M, Jin D, Cui W, Wu Y 2016 Chin. Phys. B 25 262
[42]	Wang X B, Li Y D, Cui W Z, Li Y, Zhang H T, Zhang X N, Liu C L 2016 Acta Phys. Sin. 65 047901 (in Chinese) [王新波, 李永东, 崔万照, 李韵, 张洪太, 张小宁, 刘纯亮 2016 65 047901]
[43]	Zhang C, Shao T, Niu Z, Zhang D D, Wang J, Yan P 2012 Acta Phys. Sin. 61 035202 (in Chinese) [章程, 邵涛, 牛铮, 张东东, 王珏, 严萍 2012 61 035202]

[1]	Wang Zhen, Zhao Zhi-Hang, Fu Yang-Yang. Numerical simulation study on microdischarge via a unified fluid model. Acta Physica Sinica, 2024, 73(12): 125201. doi: 10.7498/aps.73.20240392
[2]	Xiao Jiang-Ping, Dai Dong, Victor F. Tarasenko, Shao Tao. Mechanism of runaway electron generation in nanosecond pulsed plate-plate discharge at atmospheric-pressure air. Acta Physica Sinica, 2023, 72(10): 105201. doi: 10.7498/aps.72.20222409
[3]	Zhang Bing-Zhang, Song Zhang-Yong, Zhang Ming-Wu, Liu Xuan, Qian Cheng, Fang Xin, Shao Chao-Jie, Wang Wei, Liu Jun-Liang, Zhu Zhi-Chao, Sun Liang-Ting, Yu De-Yang. Theoretical and experimental studies on the captured electron population probability of hydrogen-like O and N ions in collision with Al surface. Acta Physica Sinica, 2022, 0(0): 0-0. doi: 10.7498/aps.71.20212434
[4]	Zhang Bing-Zhang, Song Zhang-Yong, Zhang Ming-Wu, Liu Xuan, Qian Cheng, Fang Xing, Shao Cao-Jie, Wang Wei, Liu Jun-Liang, Zhu Zhi-Chao, Sun Liang-Ting, Yu De-Yang. Theoretical and experimental studies on the captured electron population probability of hydrogen-like O and N ions in collision with Al surface. Acta Physica Sinica, 2022, 71(13): 133201. doi: 10.7498/aps.70.20212434
[5]	Mei Ce-Xiang, Zhang Xiao-An, Zhou Xian-Ming, Zhao Yong-Tao, Ren Jie-Ru, Wang Xing, Lei Yu, Sun Yuan-Bo, Cheng Rei, Xu Ge, Zeng Li-Xia. K-shell X-ray emission from high energy pulsed C6+ ion beam impacting on Ni target. Acta Physica Sinica, 2017, 66(14): 143401. doi: 10.7498/aps.66.143401
[6]	Liu Xue, Ran Xian-Wen, Xu Zhi-Hong, Tang Wen-Hui. Equivalence of energy deposition profile in target between electron beam of multi-energy composite spectrum and X-ray. Acta Physica Sinica, 2017, 66(2): 025202. doi: 10.7498/aps.66.025202
[7]	Zhao Guang-Yin, Li Ying-Hong, Liang Hua, Hua Wei-Zhuo, Han Meng-Hu. Phenomenological modeling of nanosecond pulsed surface dielectric barrier discharge plasma actuation for flow control. Acta Physica Sinica, 2015, 64(1): 015101. doi: 10.7498/aps.64.015101
[8]	Bai Zhan-Guo, Li Xin-Zheng, Li Yan, Zhao Kun. Numerical analysis on multi-armed spiral patterns in gas discharge system. Acta Physica Sinica, 2014, 63(22): 228201. doi: 10.7498/aps.63.228201
[9]	Zhang Cheng, Ma Hao, Shao Tao, Xie Qing, Yang Wen-Jin, Yan Ping. Runaway electron beams in nanosecond-pulse discharges. Acta Physica Sinica, 2014, 63(8): 085208. doi: 10.7498/aps.63.085208
[10]	Zhang Xiao-An, Mei Ce-Xiang, Zhao Yong-Tao, Cheng Rui, Wang Xing, Zhou Xian-Ming, Lei Yu, Sun Yuan-Bo, Xu Ge, Ren Jie-Ru. X-ray emission of C6+ pulsed ion beams of CSR impacting on Au target. Acta Physica Sinica, 2013, 62(17): 173401. doi: 10.7498/aps.62.173401
[11]	He Ya-Feng, Feng Xiao-Min, Zhang Liang. Control of the spatiotemporal pattern with time delayed feedback in a gas discharge system. Acta Physica Sinica, 2012, 61(24): 245204. doi: 10.7498/aps.61.245204
[12]	Lu Hong-Wei, Zha Xue-Jun, Hu Li-Qun, Lin Shi-Yao, Zhou Rui-Jie, Luo Jia-Rong, Zhong Fang-Chuan. The effect of gas puffing on plasma during slide-away discharge in the HT-7 tokamak. Acta Physica Sinica, 2012, 61(7): 075202. doi: 10.7498/aps.61.075202
[13]	Wu Jin-Ze, Tang Jin-E, Dong You-Er, Zhang Guo-Feng, Wang Yan-Hua. Experimental and theoretical studies on gas discharge and plasma oscillation at atmospheric pressure. Acta Physica Sinica, 2012, 61(19): 195208. doi: 10.7498/aps.61.195208
[14]	Zhang Cheng, Shao Tao, Niu Zheng, Zhang Dong-Dong, Wang Jue, Yan Ping. X-ray generation in repetitive pulsed discharge in atmospheric air with a point-to-plane gap. Acta Physica Sinica, 2012, 61(3): 035202. doi: 10.7498/aps.61.035202
[15]	Lu Hong-Wei, Hu Li-Qun, Zhou Rui-Jie, Xu Ping, Zhong Guo-Qiang, Lin Shi-Yao, Wang Shao-Feng. Runaway electrons behaviors during ion cycolotron range of frequency and lower hybrid wave plasmas in the HT-7 Tokamak. Acta Physica Sinica, 2010, 59(10): 7175-7181. doi: 10.7498/aps.59.7175
[16]	Lu Hong-Wei, Hu Li-Qun, Lin Shi-Yao, Zhong Guo-Qiang, Zhou Rui-Jie, Zhang Ji-Zong. Investigation of slide-away discharges in HT-7 tokamak. Acta Physica Sinica, 2010, 59(8): 5596-5601. doi: 10.7498/aps.59.5596
[17]	Xie Xu-Dong, Wang Xiao, Zhu Qi-Hua, Zeng Xiao-Ming, Wang Feng-Rui, Huang Xiao-Jun, Zhou Kai-Nan, Wang Fang, Jiang Dong-Bin, Huang Zheng, Sun Li, Liu Hua, Wang Xiao-Dong, Deng Wu, Guo Yi, Zhang Xiao-Mi. High energy chirped pulse characteristics observed by spectral-resolved streak camera. Acta Physica Sinica, 2007, 56(11): 6463-6467. doi: 10.7498/aps.56.6463
[18]	Guo Wen-Qiong, Zhou Xiao-Jun, Zhang Xiong-Jun, Sui Zhan, Wu Deng-Sheng. Simulation electro-optic switch of plasma-electrode Pockels cells driven by one-pulse process. Acta Physica Sinica, 2006, 55(7): 3519-3523. doi: 10.7498/aps.55.3519
[19]	Shao Tao, Sun Guang-Sheng, Yan Ping, Gu Chen, Zhang Shi-Chang. Calculation on runaway process of high-energy fast electrons under nanosecond-pulse. Acta Physica Sinica, 2006, 55(11): 5964-5968. doi: 10.7498/aps.55.5964
[20]	Zhao Yong-Tao, Xiao Guo-Qing, Zhang Xiao-An, Yang Zhi-Hu, Chen Xi-Meng, Li Fu-Li, Zhang Yan-Ping, Zhang Hong-Qiang, Cui Ying, Shao Jian-Xiong, Xu Xu. The x-ray spectra of hollow atoms. Acta Physica Sinica, 2005, 54(1): 85-88. doi: 10.7498/aps.54.85

Catalog

Vol. 66, Issue 10 - 2017-05-20

Metrics

Abstract views: 6016
PDF Downloads: 478
Cited By: 0

姓名
邮箱
手机号码
标题
留言内容
验证码

Search

Article

留言板