本文選題：偏振-太陽(yáng)　切入點(diǎn)：漢勒效應(yīng)-太陽(yáng)　出處：《中國(guó)科學(xué)院研究生院（云南天文臺(tái)）》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：太陽(yáng)磁場(chǎng)的診斷對(duì)研究太陽(yáng)物理有著重要的意義。而磁場(chǎng)的診斷通常通過(guò)塞曼效應(yīng)利用斯托克斯參量I，Q，U，和V對(duì)磁場(chǎng)進(jìn)行反演。塞曼效應(yīng)對(duì)通常只能對(duì)強(qiáng)磁場(chǎng)的進(jìn)行診斷，而太陽(yáng)寧?kù)o區(qū)存在的大量弱磁場(chǎng)很難被直接診斷。近幾十年來(lái)大量科學(xué)家進(jìn)行著利用漢勒效應(yīng)（Hanle efect）診斷弱磁場(chǎng)的研究。而利用漢勒效應(yīng)診斷弱磁場(chǎng)需要對(duì)偏振的產(chǎn)生機(jī)制有一個(gè)完整的理解。直到近年來(lái)，利用對(duì)偏振的測(cè)量精度達(dá)到105ZIMPOL（ZurichImaging Polarimeter）技術(shù)獲得以斯托克斯Q/I表征的第二太陽(yáng)光譜（Secondsolar Spectrum）展現(xiàn)豐富的散射偏振特征，促使了對(duì)偏振研究的蓬勃發(fā)展。通過(guò)對(duì)第二太陽(yáng)光譜的研究，可以使我們對(duì)偏振產(chǎn)生機(jī)制理解的更為透徹，從而使利用漢勒效應(yīng)診斷弱磁場(chǎng)逐漸成為可能。主要介紹了用量子電動(dòng)力學(xué)為基礎(chǔ)的密度矩陣來(lái)研究偏振光譜產(chǎn)生的物理過(guò)程。我們使用的是由E.LandiDegl’Innocenti在平直光譜近似下得到的公式。我們采用了7個(gè)原子能級(jí)的Mg原子模型，研究了MgI b線由散射產(chǎn)生的偏振輪廓Q/I和U/I在磁場(chǎng)中的變化。MgI b線非常適合用來(lái)研究下能級(jí)的漢勒效應(yīng)，對(duì)亞高斯的磁場(chǎng)非常敏感，沒(méi)有考慮部分頻率再分布以及輻射轉(zhuǎn)移所帶來(lái)的影響。研究的結(jié)果顯示MgI三線結(jié)構(gòu)的Q/I和U/I輪廓對(duì)磁場(chǎng)的敏感范圍分為兩段，由下能級(jí)漢勒效應(yīng)主導(dǎo)的0.001高斯到0.1高斯，有上能級(jí)漢勒效應(yīng)主導(dǎo)的1高斯到10高斯。在下能級(jí)漢勒效應(yīng)主導(dǎo)的磁場(chǎng)范圍內(nèi)，我們發(fā)現(xiàn)b4線的偏振度隨著磁場(chǎng)強(qiáng)度的增加而增加，這是由于各個(gè)能級(jí)的原子能級(jí)排列分量（atomic alignment）都通過(guò)統(tǒng)計(jì)平衡方程耦合在一起，致使下能級(jí)的原子的排列分量的變化對(duì)上能級(jí)的原子的排列分量有一定想。因此雖然b4線的下能級(jí)J為零沒(méi)有原子能級(jí)的排列分量，但是由于其他能級(jí)的反饋而使得上能級(jí)的排列分量發(fā)生變化導(dǎo)致偏振度增加，使b4線的偏振度隨磁場(chǎng)強(qiáng)度的增加而增加。研究結(jié)果表明，由鄰邊昏暗效應(yīng)所得到的不對(duì)稱因子（anisotropy factor）不適合用來(lái)處理如Mg I b線等強(qiáng)線的譜線輪廓。連續(xù)譜可以十分明顯的改變譜線的展寬。為了得到與觀測(cè)結(jié)果相吻合的MgI b譜線輪廓必須要考慮二向色性。MgI b線十分適合用來(lái)研究下能級(jí)極化的漢勒效應(yīng)，并且對(duì)亞高斯范圍的磁場(chǎng)十分敏感非常適合用來(lái)診斷色球?qū)庫(kù)o區(qū)的極弱磁場(chǎng)，另外漢勒效應(yīng)不僅可以退偏振還可以使偏振度增加。
[Abstract]:The diagnosis of the solar magnetic field is of great significance to the study of solar physics, and the diagnosis of the magnetic field usually uses the Stokes parameter I _ (Q) _ (U) and V to invert the magnetic field by Zeeman effect, which is usually only used to diagnose the strong magnetic field. In recent decades, a large number of scientists have studied the use of Hanle effect to diagnose weak magnetic field. The use of Hanle effect to diagnose weak magnetic field requires the polarization of the weak magnetic field. The mechanism of production has a complete understanding. Until recent years, The second solar spectrum (second solar spectrum), characterized by Stokes Q / I, was obtained by using the 105ZIMPOL(ZurichImaging Polarimeter technique, which promoted the development of polarization research. That will give us a better understanding of the mechanism of polarization generation, This makes it possible to diagnose the weak magnetic field by using the Hanler effect. This paper mainly introduces the density matrix based on quantum electrodynamics to study the physical process of polarized light spectrum. We use E.LandiDegl'Innocenti near the flat spectrum. We use seven atomic mg atomic models. The variation of polarization profile Q / I and U / I produced by scattering in magnetic field. MgIb line is very suitable for studying the lower energy level of Hamler effect, which is very sensitive to the magnetic field of sub#china_person0#. The results of the study show that the sensitivity range of Q / I and U / I profiles of MgI three-wire structure to magnetic field is divided into two segments, 0.001 Gao Si and 0.1 Gao Si, which are dominated by the lower energy level Hanler effect. In the magnetic field range dominated by the lower energy level Hansel effect, we find that the polarization degree of the b4 line increases with the increase of the magnetic field intensity. This is because atomic atomic alignment components of each energy level are coupled by statistical equilibrium equations. The change of the permutation components of the atoms of the lower energy level has a certain effect on the permutation components of the atoms of the upper energy level. Therefore, although the lower energy level J of the b4 line is zero, there is no atomic level permutation component. However, due to the feedback from other energy levels, the polarization degree of the upper energy level increases, and the polarization of the b4 line increases with the increase of the magnetic field intensity. The asymmetric factor derived from the adjacent dim effect is not suitable for dealing with the line profiles of strong lines such as the MgIb line. The continuous spectrum can obviously change the broadening of the spectral lines. The outline of MgI b line must consider the dichroism. MgIb line is very suitable for studying the Hansel effect of lower level polarization. Moreover, it is very sensitive to the magnetic field in the range of sub-#china_person0# and is suitable for diagnosing the extremely weak magnetic field in the quiet region of the color sphere. In addition, the Hanler effect can not only depolarization but also increase the degree of polarization.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院（云南天文臺(tái)）
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P182

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1 李昊;太陽(yáng)散射偏振性質(zhì)研究[D];中國(guó)科學(xué)院研究生院（云南天文臺(tái)）;2014年

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本文編號(hào)：1650468