本文選題：實(shí)驗(yàn)室天體物理 + 激光與物質(zhì)相互作用��； 參考：《中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)》2017年博士論文

【摘要】：實(shí)驗(yàn)室天體物理學(xué)是強(qiáng)激光科學(xué)與天體物理學(xué)的交叉前沿學(xué)科,利用強(qiáng)激光等實(shí)驗(yàn)手段,可以在實(shí)驗(yàn)室中創(chuàng)造出類似天體環(huán)境的極端物理?xiàng)l件,從而對(duì)天體物理過程、機(jī)制進(jìn)行全面、深入、可控的研究。利用強(qiáng)激光與物質(zhì)相互作用進(jìn)行的實(shí)驗(yàn)室天體物理研究已為理解多種天體物理問題做出了貢獻(xiàn)。本論文主要針對(duì)宇宙中普遍發(fā)生的星際介質(zhì)和天體相互作用過程,利用高功率激光實(shí)驗(yàn)和理論模擬,深入研究了其中的物理機(jī)制和相關(guān)現(xiàn)象。首先,我們利用高功率激光照射CH平面靶后產(chǎn)生的等離子體撞擊柱狀障礙物的方法,進(jìn)行了弓激波實(shí)驗(yàn),生成了高馬赫數(shù)的弓激波。通過陰影和干涉成像診斷,成功觀測(cè)到了弓激波的形成及演化。在1 ns延遲時(shí)刻,等離子云的馬赫數(shù)約為15,隨著時(shí)間推移,等離子體流的馬赫數(shù)降低,導(dǎo)致了弓激波張角和形狀的變化。此外,我們?cè)趯?shí)驗(yàn)中探測(cè)到弓激波的寬度約為50μm,這與離子間的平均碰撞自由程相當(dāng),該結(jié)果證明了該弓激波的形成機(jī)制主要是離子間的碰撞效應(yīng)。我們采用二維USIM流體程序,模擬了等離子體云和障礙物相互撞擊的過程,模擬結(jié)果很好地再現(xiàn)了實(shí)驗(yàn)結(jié)果。其次,利用高功率激光照射固體靶產(chǎn)生的等離子體,模擬了太陽風(fēng)和彗星相互作用的過程。通過陰影和干涉成像診斷,成功地觀測(cè)到了障礙物后產(chǎn)生了具有斷裂結(jié)構(gòu)的等離子體尾。通過粒子程序模擬,我們發(fā)現(xiàn)撞擊后的等離子體中,離子和電子間巨大的熱速度差異,使障礙物后方產(chǎn)生了電場(chǎng),電場(chǎng)吸引離子向中間匯聚,導(dǎo)致中間等離子體密度增加形成尾巴,并在尾巴前端出現(xiàn)密度跳變結(jié)構(gòu)。該結(jié)果揭示了導(dǎo)致彗星斷尾事件的又一可能原因。最后,我們利用強(qiáng)激光照射金屬絲靶,獲得了圍繞金屬絲的環(huán)形強(qiáng)磁場(chǎng),利用B-dot探頭對(duì)磁場(chǎng)的強(qiáng)度進(jìn)行了測(cè)量,并通過模擬,計(jì)算出了磁場(chǎng)的空間分布;又利用強(qiáng)激光與CH平面靶相互作用產(chǎn)生的超音速等離子體撞擊該金屬絲的方法,研究了磁場(chǎng)對(duì)弓激波的作用,實(shí)驗(yàn)中觀察到了磁場(chǎng)的存在對(duì)弓激波的影響;同時(shí),通過實(shí)驗(yàn)室天體物理定標(biāo)率的變換,證明了激光照射CH靶產(chǎn)生的強(qiáng)x射線所離化的金屬絲等離子體,可以被用來模擬太陽風(fēng)等離子體。
[Abstract]:Laboratory astrophysics is an interdisciplinary frontier subject of intense laser science and astrophysics. By means of experiments such as intense laser, extreme physical conditions similar to the celestial environment can be created in the laboratory, and thus the astrophysical process can be studied. The mechanism is studied comprehensively, deeply and controllably. The study of laboratory astrophysics by means of the interaction of intense laser and matter has contributed to the understanding of many kinds of astrophysical problems. In this paper, the physical mechanism and related phenomena of the interstellar medium and celestial bodies are studied by means of high-power laser experiments and theoretical simulations. Firstly, by using the method of the plasma impingement on the cylindrical obstacle produced by the high power laser irradiation on the Ch plane target, the bow shock wave with high Mach number is generated. The formation and evolution of bow shock waves were observed successfully by shadow and interference imaging diagnosis. At 1 ns delay time, the Mach number of plasma cloud is about 15. Over time, the Mach number of plasma flow decreases, resulting in the change of bow shock angle and shape. In addition, the width of the bow shock wave is about 50 渭 m, which is equivalent to the average collision free path between ions. The results show that the formation mechanism of the bow shock wave is mainly the collision effect between ions. A two-dimensional USIM fluid program is used to simulate the interaction between the plasma cloud and the barrier. The simulation results reproduce the experimental results well. Secondly, the interaction between the solar wind and the comet is simulated by using the plasma produced by the high power laser irradiation on the solid target. Through shadow and interference imaging diagnosis, the plasma tail with broken structure was successfully observed behind the obstacle. By means of particle program simulation, we find that the great difference in thermal velocity between ions and electrons in the plasma after impact creates an electric field behind the barrier, and the electric field attracts the ions to converge toward the middle. The intermediate plasma density increases to form a tail and a density jump structure appears at the front end of the tail. The results reveal another possible cause of comet tail breakage. Finally, the circular strong magnetic field around the wire is obtained by using a strong laser beam. The intensity of the magnetic field is measured by B-dot probe, and the spatial distribution of the magnetic field is calculated by simulation. The effect of magnetic field on bow shock wave is studied by supersonic plasma impinging on the wire by interaction of intense laser with Ch plane target. The influence of magnetic field on bow shock wave is observed in the experiment. Through the conversion of the calibration rate of the laboratory astrophysics, it is proved that the ionization of metal wire plasma produced by strong x-ray from the Ch target irradiated by laser can be used to simulate the solar wind plasma.
【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P14

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