入射震波馬赫數 1.30~1.69 範圍的震波於低溫電漿包覆球面上交互作用之觀察研究完成於國立成功大學航空太空工程所之震波管設備中。本實驗中利用視流技術之彩色紋影法來擷取於震波於球面之反射與繞射的流場波形結構情形。首先，平面震波與球面的交互作用之下先形成正規反射。當入射平面震波越往下游傳遞時，曲面反射震波的半徑會隨著時間而增大，且最後交互作用之反射情形會由正規反射演變至馬赫反射。當入射馬赫數越大時會有較強的入射震波而且反射震波的強度也會較大。在入射馬赫數較大時低溫電漿造成的效應越明顯，因低溫電漿的特性，震波行經弱電離的區域會造成震波強度變弱。由在實驗中可以觀察到在低溫電漿的作用之下震波的厚度較厚。同理可證在低溫電漿的作用之下所量測到反射震波壓力訊號的壓升情況較小，也可以確認震波強度確實變弱。

The observation of the interaction between a planar shock wave of Mach number 1.3-1.69 and a semisphere both in air and in nonhomegeneous plasmas has been done in the shock tube facility of Institute of Aeronautics and Astronautics in National Cheng-Kung university. The flow structure includes shock reflection and diffraction over a semisphere were been recorded by color schlieren flow visualization technique. On the begining, the interaction between a planar incident shock wave and a semisphere forms a regular reflection wave pattern. With the incident shock wave propagates downstream on the surface of semisphere, the radius of curvature of the reflected shock wave increased and it is transition into a Mach reflection finally. With a higher incident Mach number, it produces a stronger incident shock wave and the strength of the reflection shock is also stronger accordingly. The nonequilibrium plasmas effect is more obvious also. The shock wave propagation in weakly ionized gas can result in broadening and weakening of the shock. This experiment verifies that the thickness of the shock in weakly ionized gas is wider than in air. Also, the pressure jump of PT1 across the shock tube end-wall reflected shock wave across the weakly ionized gas is reduce comparing to the jump in air.

[1] Shalom Eliezer and Yaffa Eliezer, The fourth state of matter :an introduction to plasma science, Institute of Physics Pub, 2nd ed, 2001.
[2] Sun Zongxiang, “ Progress in Plasma Assisted Drag Reduction Technology,” Advances in Mechanics, Vol. 33, No. 1, 2003.
[3] V. I. Khorunzhenko, D. V. Roupassov, and A. Yu. Starikovskii, “ Hypersonic Flow and Shock Wave Structure Control by Low Temperature Nonequilibrium Plasma of Gas Discharge,” AIAA Paper 2002-3569, 2000.
[4] J. Reece Roth, “ Investigation of Uniform Glow Discharge in Atmospheric Air,” AFOSR Final Scientific Report, PSL-95-4, April 1, 1994-March 31, 1995
[5] J. Reece Roth and Daniel M. Sherman, “ Boundary Layer Flow Control with A One Atmosphere Uniform Glow Discharge Surface Plasma,” AIAA Paper 98-0328, 1998.
[6] M. R. Malik, L. M. Weinstein, and M. Y. Hussani, “ Ion Wind Drag Reduction,” AIAA Paper 86-0231, 1983.
[7] R. Yano, V. Contini, E. Plonjes, P. Palm, S. Merriman, S. Aithal, and I. Adamovich, “ Supersonic Nonequilibrium Plasma Wind-Tunnel Measurements of Shock Modification and Flow Visualization,” AIAA Journal Vol. 38, No. 10, October 2000.
[8] Samuel Merriman, Elke Ploenjes, Peter Palm, and Igor V. Adamovich, “ Shock Wave Control by Nonequilibrium Plasmas in Cold Supersonic Gas Flows,” AIAA Paper 2000-2327, 2000.
[9] Samuel Merriman, Adam Christian, Rodney Meyer, Brett Kowalczyk, and Peter Palm, “ Studies of Conical Shock Wave Modification by Nonequilibrium RF Discharge Plasma,” AIAA Paper 2001-0347, 2001.
[10] Rodney Meyer, Peter Palm, Elke Ploenjes, J. William Rich, and Igor V. Adamovich, “ The Effect of A Nonequilibrium RF Discharge Plasma on A Conical Shock Wave in A M=2.5 Flow,” AIAA Paper 2001-3059, 2001.
[11] A. I. Klimov, A. N. Koblov, G. I. MIshin, Y. L. Serov, and I. P. Yavor, “ Shock Wave Propagation in A Glow Discharge,” Soviet Technical Physics Letters, Vol. 8, No. 4, 1982, pp. 192-194.
[12] P. A. Voinovich, A. P. Ershov, S. E. Ponomareva, and V. M. Shibov, “ Propagation of Weak Shock Waves in Plasma of Longitudinal Flow Discharge in Air,” High Temperature, Vol. 29, No. 3, 1991, pp. 468-476.
[13] William M. Hilbun, “ Shock Waves in Nonequilibrium Gases and Plasmas,” Ph.D. dissertation, Air Force Institute of Technology, October 1997.
[14] Valentin Bityurin, Anatoly Klimov, Sergey Leonov, Vadim Brovkin, and Yury Kolesnichenko, “ Shock Wave Structure and Velocity at Propagation through Non-homogenous Plasma,” AIAA Paper 2000-2571, 2000.
[15] P. Bletzinger, B. N. Ganguly, and A. Garscadden, “ Mutual Interactions between Low Mach Number Shock Waves and Nonequilibrium Plasmas,” AIAA Paper 2001-3050, 2001.
[16] Sohail H. Zaidi, M. N. Shneider, D. K. Mansfield, Y. Z. Ionikh, and R. B. Miles, “ Influence of Upstream Pulsed Energy Deposition on a Shockwave Structure in Supersonic Flow,” AIAA Paper 2002-2703, 2002.
[17] Yu. Z. Ionikh, N. V. Chernysheva, A. P. Yalin, S. O. Macheret, L. Martinelli, and R. B. Miles, “ Shock Wave Propagation through Glow Discharge Plasmas: Evidence of Thermal Mechanism of Shock Dispersion,” AIAA Paper 2000-0714, 2000.
[18] Gabi Ben-dor, Shock Wave Reflection Phenomena, Springer-Verlag, 1992.
[19] Z. Han and X. Yin, Shock Dynamics, Kluwer Academic, 1993.
[20] Richard J. Goldstein, Fluid Mechanics measurements, Taylor&Franicis, 1996.
[21] V. E. Golant, A. P. Zhilinsky and I. E. Sakharov, Fundamentals of Plasma Physics , J. Wiley, 1980.
[22] 陳偉仁,”平面震波於楔形體與垂直鰭片模型所產生反射-繞射現象之探討 ”,成功大學航空太空工程研究所碩士論文, 2004.
[23] Z. T. Deng, Ruben Rojas-Oviedo, Alan Chow, and Ron Litchford, “ Prediction of Shock Wave Structure in Weakly Ionized Gas Flow,” AIAA Paper 2002-2181, 2002.
[24] G. I. Mishin, “ Total Pressure behind a Shock Wave in Weakly Ionized Air,” Sov. Tech. Physics Letter, Vol. 20, Page 857-859, 1994.