本文選題：上合期間 + 深空通信��； 參考：《哈爾濱工業(yè)大學(xué)》2017年博士論文

【摘要】：作為傳輸探測(cè)信息的唯一載體,深空通信是人類開展深空探測(cè)活動(dòng)的重要手段。連接深空探測(cè)器和地球觀測(cè)站間的無(wú)線電波在上合期間會(huì)穿過(guò)太陽(yáng)日冕區(qū),該區(qū)域高濃度、強(qiáng)不規(guī)則性的太陽(yáng)風(fēng)湍渦等離子體會(huì)引起無(wú)線電波的衰減和鏈路通信質(zhì)量的下降,甚至引發(fā)通信中斷,進(jìn)而對(duì)深空探測(cè)的正常開展造成嚴(yán)重的影響。因此,構(gòu)建可靠的深空通信網(wǎng)是未來(lái)深空探測(cè)的重要保障,而如何準(zhǔn)確計(jì)算日冕區(qū)太陽(yáng)風(fēng)對(duì)無(wú)線電波的影響已成為深空通信中亟需解決的問(wèn)題。目前,對(duì)這一課題的研究主要集中于以下兩方面,一方面,考慮日徑距離(太陽(yáng)到無(wú)線鏈路的垂直距離)大于4Rsun時(shí),背景太陽(yáng)風(fēng)對(duì)沿直線傳播的無(wú)線電波的吸收預(yù)測(cè)模型。另一方面,考慮各向同性湍渦媒質(zhì)折射指數(shù)變化所引起的電波信號(hào)隨機(jī)起伏變化,給出幅度起伏、相位起伏和到達(dá)角起伏的預(yù)測(cè)模型。然而,隨深空探測(cè)活動(dòng)的增多,日冕區(qū)太陽(yáng)風(fēng)對(duì)日徑距離小于4Rsun時(shí)的電波吸收和各向異性湍渦下太陽(yáng)閃爍的影響變得更為嚴(yán)重,并已成為制約未來(lái)深空通信發(fā)展的技術(shù)瓶頸。如何準(zhǔn)確預(yù)測(cè)日冕區(qū)太陽(yáng)風(fēng)對(duì)深空無(wú)線電波的影響將成為深空通信發(fā)展的關(guān)鍵。因此,無(wú)論是對(duì)4Rsun內(nèi)電波衰減的預(yù)測(cè),還是對(duì)各向異性湍渦下太陽(yáng)閃爍的預(yù)測(cè)都是深空通信的基礎(chǔ)性和前瞻性課題,并已成為深空電波傳播領(lǐng)域的熱點(diǎn)研究問(wèn)題。本文以日冕區(qū)背景太陽(yáng)風(fēng)和隨機(jī)起伏太陽(yáng)風(fēng)對(duì)電波傳播影響為目標(biāo),針對(duì)已有工作不足之處,以隨機(jī)媒質(zhì)中電波傳播理論為出發(fā)點(diǎn),探索日冕區(qū)太陽(yáng)風(fēng)對(duì)電波吸收的準(zhǔn)確預(yù)測(cè)模型,在考慮太陽(yáng)風(fēng)湍渦各向異性特點(diǎn)的基礎(chǔ)上,進(jìn)一步研究太陽(yáng)閃爍對(duì)無(wú)線電波幅度、相位和到達(dá)角起伏的影響,并系統(tǒng)闡述日冕區(qū)太陽(yáng)風(fēng)對(duì)電波傳播的影響機(jī)理,從而為未來(lái)深空探測(cè)中上合期間深空通信的正常開展提供研究思路。論文首先建立了日冕區(qū)鏈路方向電子含量變化模型,在此基礎(chǔ)上,具體分析日冕區(qū)太陽(yáng)風(fēng)對(duì)穿過(guò)其中無(wú)線電波相位、傳播時(shí)間、信號(hào)頻率和極化特性的影響,并研究近日點(diǎn)處太陽(yáng)風(fēng)等離子體薄層對(duì)無(wú)線電波的反射率、透射率和吸收率。針對(duì)日徑距離小于4Rsun時(shí),背景太陽(yáng)風(fēng)對(duì)電波吸收的影響,論文提出一種考慮太陽(yáng)磁場(chǎng)變化的相對(duì)介電常數(shù)計(jì)算方法,并分別給出無(wú)線電波在左極化和右極化模式下的修正衰減預(yù)測(cè)模型,最后,結(jié)合WKB近似理論分析提出預(yù)測(cè)模型與傳統(tǒng)模型的對(duì)比結(jié)果,此外利用提出的衰減預(yù)測(cè)模型,論文進(jìn)一步給出不同日徑距離下的電波衰減值。考慮弱太陽(yáng)閃爍下太陽(yáng)風(fēng)湍渦不規(guī)則性對(duì)無(wú)線電波幅度起伏的影響,論文分析了上合期間鏈路幾何模型和湍渦媒質(zhì)起伏特性。在此基礎(chǔ)上,依據(jù)“泰勒凍結(jié)理論”將太陽(yáng)風(fēng)湍渦假設(shè)成緩慢變化的隨機(jī)媒質(zhì),并利用Rytov近似理論給出幅度起伏預(yù)測(cè)模型和弱太陽(yáng)閃爍下的閃爍指數(shù)預(yù)測(cè)模型。研究發(fā)現(xiàn),日冕區(qū)背景參數(shù)對(duì)幅度起伏有較為復(fù)雜的影響,且閃爍指數(shù)隨日徑距離的減小而增大。考慮到太陽(yáng)風(fēng)湍渦受太陽(yáng)磁場(chǎng)影響具有各向異性的特點(diǎn)并隨日徑距離的增大趨于各向同性,論文進(jìn)一步分析了各向異性和各向同性模型下的閃爍指數(shù)性能。研究結(jié)果表明,提出的閃爍指數(shù)預(yù)測(cè)模型與實(shí)測(cè)數(shù)據(jù)較為吻合,且其預(yù)測(cè)精度遠(yuǎn)大于其他預(yù)測(cè)模型。針對(duì)上合期間無(wú)線電波受太陽(yáng)閃爍影響所產(chǎn)生的相位起伏問(wèn)題,論文系統(tǒng)地分析了上合期間鏈路幾何模型及太陽(yáng)風(fēng)湍渦譜特性,并研究了太陽(yáng)風(fēng)速度、湍渦外尺度和湍渦譜指數(shù)對(duì)相位起伏的影響,利用幾何光學(xué)法論文給出了相位起伏的預(yù)測(cè)模型,以及相位起伏方差和相位起伏功率譜的計(jì)算模型。此后,論文重點(diǎn)討論了日冕區(qū)背景參數(shù)對(duì)相位起伏的影響及各參數(shù)的綜合影響。與實(shí)測(cè)數(shù)據(jù)的對(duì)比結(jié)果表明,提出預(yù)測(cè)模型具有較高的預(yù)測(cè)精度�？紤]在較大日徑距離范圍時(shí)太陽(yáng)風(fēng)湍渦具有各向同性的特點(diǎn),論文基于Rytov近似理論和各向同性的湍渦譜模型推導(dǎo)了各向同性模型下的到達(dá)角起伏預(yù)測(cè)模型。為評(píng)估天線口徑平滑效應(yīng)的影響,提出模型將Airy函數(shù)替換為高斯函數(shù),并進(jìn)一步推導(dǎo)到達(dá)角起伏的功率譜模型。針對(duì)無(wú)線電波穿過(guò)各向異性日冕區(qū)湍渦的情形,論文從工程角度分析了到達(dá)角起伏與相位起伏的關(guān)系,并利用幾何光學(xué)法下的相位起伏模型推導(dǎo)給出到達(dá)角起伏預(yù)測(cè)模型。在此過(guò)程中,論文通過(guò)Booker電子密度譜考慮了各向異性太陽(yáng)風(fēng)湍渦的影響。利用上述推導(dǎo)得到的到達(dá)角起伏預(yù)測(cè)模型,論文分析了日冕區(qū)背景參數(shù)對(duì)到達(dá)角起伏的影響,并對(duì)比分析兩種預(yù)測(cè)模型的預(yù)測(cè)精度。在此基礎(chǔ)上,論文進(jìn)一步分析了無(wú)線電波工作頻率和天線口徑對(duì)鏈路增益的影響。
[Abstract]:As the only carrier for transmission detection information, deep space communication is an important means for human to carry out deep space exploration activities. The radio waves connecting deep space detectors and earth observation stations will pass through the solar coronal area during the up period. The high concentration, strong irregularity of the solar wind eddy plasma experience causes the attenuation and chain of radio waves in this region. The decline of the quality of the road communication, even the interruption of communication, has a serious effect on the normal development of deep space exploration. Therefore, the construction of a reliable deep space communication network is an important guarantee for the future deep space detection, and how to accurately calculate the influence of the solar wind on the radio waves in the corona area has become an urgent problem in the deep space communication. The research on this subject is mainly focused on the following two aspects. On the one hand, considering the absorption prediction model of the background solar wind to the radio waves propagating along the straight line when the diurnal distance (the vertical distance of the sun to the wireless link) is greater than 4Rsun. On the other hand, the wave signal caused by the refraction index changes of the isotropic turbulent medium is taken into account. The prediction model of amplitude fluctuation, phase fluctuation and arrival angle fluctuation is given. However, with the increase of deep space exploration activity, the solar wind in the coronal region has more serious influence on the wave absorption and the anisotropy under the anisotropic turbulent vortex, which has become a technical bottleneck for the development of the future deep space communication. How to accurately predict the influence of solar wind in coronal region on deep space radio waves will be the key to the development of deep space communications. Therefore, both the prediction of the attenuation in the 4Rsun and the prediction of the solar scintillation under the anisotropic eddy are both basic and forward-looking topics in the deep space communication, and have become a hot spot in the field of deep space radio transmission. In this paper, this paper aims at the influence of the solar wind and random fluctuating solar wind on the wave propagation in coronal region. In view of the shortcomings of the existing work, the accurate prediction model of the solar wind absorption in the coronal region is explored, based on the theory of the wave propagation in the random medium, and the anisotropy of the solar wind eddy is considered. The influence of the solar scintillation on the amplitude, phase and arrival angle fluctuation of the radio wave is further studied, and the influence mechanism of the solar wind on the wave propagation in the coronal region is systematically expounded, so as to provide the research ideas for the normal development of the deep space communication during the sounding of the deep space in the future. On this basis, the influence of solar wind on the phase, propagation time, signal frequency and polarization characteristics of the radio waves through the coronal region is analyzed, and the reflectance, transmittance and absorption of the solar wind plasma thin layer at the perihelion are studied. The background solar wind is absorbed by the solar wind when the solar wind is less than 4Rsun. The paper presents a method for calculating the relative dielectric constant of the solar magnetic field, and gives the modified Attenuation Prediction Model of the radio waves in the left and right polarization modes. Finally, the comparison results of the prediction model with the traditional model are presented with the WKB approximation theory. In addition, the proposed Attenuation Prediction model is used. This paper further gives the attenuation values of the radio waves under different diurnal distances. Considering the influence of the irregularity of the solar wind vortex under the weak solar scintillation on the amplitude fluctuation of the radio waves, the paper analyses the geometric model of the link and the undulating characteristics of the turbulent eddy medium during the up period. On this basis, the solar wind eddy is assumed to be slow on the basis of the "Taylor freezing theory". The amplitude fluctuation prediction model and the scintillation index prediction model under the weak sun flicker are given by the Rytov approximation theory. It is found that the background parameters of the coronal region have a more complex effect on the amplitude fluctuation, and the scintillation index increases with the decrease of the diurnal distance. It has anisotropic characteristics and tends to isotropy with the increase of diurnal distance. The paper further analyzes the performance of the scintillation index under anisotropic and isotropic model. The results show that the proposed model is more consistent with the measured data, and its prediction precision is far greater than that of other prediction models. The problem of phase fluctuation caused by the solar scintillation is caused by the linear wave. This paper systematically analyzes the geometric model of the link and the spectral characteristics of the solar wind turbulence, and studies the influence of the solar wind velocity, the outer scale of the turbulent vortex and the spectral index of the turbulence on the phase fluctuation, and the prediction model of the phase fluctuation is given by the geometrical optics method. The calculation model of the phase fluctuation variance and phase fluctuation power spectrum. After that, the paper focuses on the influence of the coronal background parameters on the phase fluctuation and the comprehensive influence of the parameters. The comparison with the measured data shows that the prediction model has a higher prediction accuracy. Based on the Rytov approximation theory and the isotropic turbulent eddy spectrum model, the paper derives the prediction model of the arrival angle fluctuation under the isotropic model. In order to evaluate the effect of the antenna aperture smoothing, the model is put forward to replace the Airy function as Gauss's function, and to further deduce the power spectrum model of the angular fluctuation. The relationship between the arrival angle fluctuation and the phase fluctuation is analyzed from the engineering angle, and the prediction model of the arrival angle fluctuation is derived from the phase fluctuation model under the geometric optics method. In this process, the paper considers the shadow of the anisotropic solar wind eddy through the Booker electron density spectrum. In this paper, the influence of the background parameters on the arrival angle fluctuation of the coronal region is analyzed and the prediction accuracy of the two prediction models is analyzed. On this basis, the influence of the frequency of radio wave and the aperture of the antenna to the link gain is further analyzed.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：V443.1;P353.8

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1 徐冠軍;日冕區(qū)太陽(yáng)風(fēng)對(duì)深空電波傳播影響的研究[D];哈爾濱工業(yè)大學(xué);2017年

2 明勇;基于大數(shù)據(jù)技術(shù)的太陽(yáng)風(fēng)研究及MHD仿真[D];成都理工大學(xué);2016年

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