中文摘要：

深空探测器信号穿过地球电离层时会产生信号时延和相位抖动，从而对VLBI（Very Long Baseline Interferometry）测量精度产生很大影响．利用日本SELENE2颗小卫星Rstar和Vstar的4测站6基线长达1yr的同波束VLBI观测数据，首次解算出了双差分电离层电子总量抖动的均方根和角距离的关系模型．6条基线的双差分电离层电子总量抖动的均方根r（单位为TECU）和角距离θ（°）的关系模型为：r=0．7730＋0．562，由基线反演出的4个测站的关系模型为：r=0．5540＋0．399．研究成果对差分相时延的解算和行星电离层掩星观测研究均有重要参考意义．

英文摘要：

Time delay and phase fluctuation are produced when the signals of spacecraft transmit through the ionosphere of earth. Thus it has great influence on the measurement precision of VLBI （Very Long Baseline Interferometry）. Using the 1-year same-beam VLBI data which were gotten from 2 satellites （Rstar and Vstar） in Japanese lunar exploration project SELENE, we obtained a model of the relation between the fluctuation of double differential total electron content in ionosphere and angular distance of the two satellites. For the 6 baselines, the root mean square r of fluctuation （in unit of TECU） and angular distance of the two satellites θ （in unit of °） has a relation of r = 0.7730 ＋ 0.562, and for the 4 VLBI stations, the relation is r = 0.5540 ＋ 0.399. The result can serve as a reference for resolving time delay of differential phase and study of planetary ionosphere.