【作者】 瞿海燕；

【导师】 袁萍；

【作者基本信息】 西北师范大学 ， 原子与分子物理， 2011， 硕士

【摘要】 依据在西藏那曲地区由无狭缝光栅摄谱仪获得的闪电放电通道的光谱资料,选取3个多回击自然闪电过程的光谱,并将其中一次闪电放电过程的光谱与同步的电学观测相结合,首次讨论了光谱特征和通道温度与闪电放电特性、电流热效应的相关性。研究结果表明,多回击放电过程中,闪电光谱的结构有明显变化,一次闪电不同回击过程的通道温度有明显差异,闪电前期的温度通常较高,之后呈逐渐降低趋势;光谱总强度与辐射电场的变化幅度、放电电流的大小成正比。另外,通道温度与回击过程传输的能量正相关,但二者的变化幅度不具有固定的比例关系,反映了不同回击中通道电阻、热量的传导、辐射、回击通道的初始温度等因素的差异,也与电场和电流的变化不完全同步有关。这项工作为进一步的高时间分辨率闪电光谱试验以及闪电过程光电相关性的研究和物理机制的探讨提供了参考数据。在此基础上,依据在山东地区利用无狭缝红外摄谱仪获得的波长在760～970nm范围的闪电近红外光谱,通过中性原子(NI、OI)的辐射计算了每个闪电沿回击通道不同位置处的温度;首次讨论了红外辐射阶段闪电放电等离子体温度和光谱总强度沿放电通道的演化特征。结果分析表明,近红外光谱主要是闪电回击后期的辐射,不同闪电的光谱结构差异不大,通道温度较回击初期和发展阶段降低,约为16000K左右。地闪通道的温度和光谱总强度沿放电通道的变化趋势与回击前期基本一致,即同一放电通道内,随着高度的增加略呈减小趋势,在近地端最大,与云-地闪电过程的光学观测相吻合;云闪通道的温度和光谱总强度沿放电通道非单调性变化,在通道的拐弯、分叉以及结点附近二者发生突变。为闪电放电的低温低电流过程以及通道的冷却提供一些新的信息,对闪电过程物理机制以及伴随的化学效应的研究有重要的意义。更多还原

【Abstract】 According to the spectra data of cloud-to-ground (CG) lightning discharge channel have been obtained by using a Slite-less spectrogrograph on Chinese Tibet Plateau, selected the spctra of three lightning processes with multiple return strokes,and combining the spectra of one of the lightning with synchronous electrical information, the correlation among spectral properties, channel temperatures and discharge characteristics, thermal effects of current is discussed for the first time. The results show that the spectral structure varies obviously in different stages of multiple-stroke lightning discharge, and the channel plasma temperature varies significantly from stroke to stroke within a given flash, in other words, the temperatures in initial stage of flash are higher, and then decreases gradually afterwards. The total intensity of spectra is directly proportional to the amplitude of electric field change as well as intensity of discharge current. Moreover, the positive correlation has been confirmed between the channel plasma temperature and the thermal effect which shows the effect of the electric current accumulation. It is confirmed that channel temperature is correlated positively with the energy transmission in one return stroke, but there is no fixed proportionality for them. The main reason may be the discrepancies in channel resistances, heat capacities, and other factors during different strokes, even related to the incomplete synchronization between the electric field and the change of the current in decay stage. The results in this work will give some reference date for futher experiments on high time resolved spectra, study on correlation between spectra and electrical parameters and research on lightning physical mechanism in lightning discharge process.Based on this work, lightning spectra in the near-infrared region of 760 to 970nm were obtained by using Slit-less infrared spectrograph in Shandong region, the temperatures at different positions along the discharge channel are calculated according to neural nitrogen and oxygen radiation, respectively. The evolution characteristic between the channel plasma temperature and the total intensity of spectra along the stroke channel during near-infrared radiation are discussed for the first time. It has been found that the near-infrared spectrum is mainly the contribution of radiation from latter stage of lightning discharge, and there is little difference for spectral structure of different lightning. Moreover, the results show that the channel temperatures are lower than the initial stage and the developing stage of return stroke, and the temperature decreases to 16,000K during this period. In addition, the change tend between the channel temperature and the total intensity of spectra along the stroke channel was consistent with the initial stage of discharge for CG lightning, in other words, for a certain return stroke channel, temperatures and the total intensity of spectra at different positions show signs of falling away with increasing height alone the discharge channel, and it highest in near ground. The result is in accordance with the optical observation of lightning discharge. But there is non-uniformly varied between them in cloud lightning. Also, the channel temperature and the total intensity of spectra are sudden changes in the tortuous positions and the branches and the crunodes of the lightning channel. This work will provide new information on discharge processes with lower amplitude currents and temperatures, and perhaps channel cooling.更多还原