发展我国的空间用高准确度原子钟

原子钟在科学技术、军事和商业中应用甚广,在空间任务,特别是卫星导航系统中起着决定性作用。目前我国还没有自己的空间用高准确度原子频标,发展适合空间应用的星载原子钟是我们面临的迫切任务。     

微波电离型原子氧源的降能和中性化系统

在把微波电子回旋共振技术应用到离子源中,获得了１０＾１５个原子／（ｃｍ＾３．ｓ）束流的基础上,采用了结构新的降能和中性化系统,把高能氧离子转变为低能氧原子;成功地研制出了一种新颖的原子氧环境效应地面模拟试验装置。由该装置获得的粒子在能量和类型方面均与低地球轨道环境相一致,从而实现了对低地球轨道环境的真实模拟。     

国际原子时进展中的原子钟

对近几年国际原子时 (TAI)进展中不同类型原子钟和不同时间实验室原子钟贡献的权重进行了比较 。     

本地标准时间频率的产生与保持

近年来，地方协调时UTC(BIRM)守时能力稳步提升，截至目前，UTC(BIRM)与UTC的相对频率偏差优于3E-14，时间偏差优于20ns。本文概括介绍了守时系统的组成，本地频率驾驭与主备同步技术，以及TA(BIRM)算法研究等。     

The STARK-B database as a resource for “STARK” widths and shifts data: State of advancement and program of development

“Stark” broadening theories and calculations have been extensively developed for about 50 years and can now be applied to many needs, especially for accurate spectroscopic diagnostics and modeling. This requires the knowledge of numerous collisional line profiles. Nowadays, the access to such data via an online database becomes essential. STARK-B is a collaborative project between the Astronomical Observatory of Belgrade and the Laboratoire d’Étude du Rayonnement et de la matière en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion collisions (impacts). It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipments and technological plasmas. Hence, the domain of temperatures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. STARK-B has been fully opened since September 2008 and is in free access.     

GNSS receiver clock modeling when using high-precision oscillators and its impact on PPP

Processing data from Global Navigation Satellite Systems (GNSS) always requires time synchronization between transmitter and receiver clocks. Due to the limited stability of the receiver’s internal oscillator, the offset of the receiver clock with respect to the system time has to be estimated for every observation epoch or eliminated by processing differences between simultaneous observations. If, in contrast, the internal oscillator of the receiver is replaced by a stable atomic clock one can try to model the receiver clock offset, instead of estimating it on an epoch-by-epoch basis. In view of the progress made in the field of high-precision frequency standards we will investigate the technical requirements for GNSS receiver clock modeling at the carrier phase level and analyze its impact on the precision of the position estimates.     

长河二号授时监测接收机设计与实现

长波授时系统是目前国际上授时精度较高的大型地基无线电授时服务系统，其授时信号采用罗兰C信号发播体制，具有作用距离远、稳定性好、可靠性高、抗干扰能力强等优点。针对GNSS信号在某些特定区域易被干扰、易失锁的问题，设计并实现了一种长河二号授时监测接收机，采用信号完好性检测、ASF（附加二次相位因子）时延修正等技术，实现了高精度、高可靠长波授时与时差监测，可作为GNSS授时的重要补充手段。     

影响氢原子钟长期稳定度的系统效应分析

进一步改进氢钟的频率稳定度，需要了解影响频率稳定度的各个过程及其影响的相对大小。讨论影响氢钟频率稳定度的各种系统过程。这种分析能够使钟的研制者和用户去识别稳定度的限制因素并加以选择以便改进。     

An investigation of the solar cycle impact on the lower thermosphere O(S) nightglow emission as observed by WINDII/UARS

The yearly variation of the integrated emission rate of the O(¹S) nightglow in the lower thermosphere is studied and the solar cycle impact is examined from the observations of the Wind Imaging Interferometer (WINDII) operated on the Upper Atmosphere Research Satellite (UARS). More than 300,000 volume emission rate profiles of the O(¹S) nightglow observed by WINDII for 40°S–40°N latitudes during November 1991–August 1997 over half of a solar cycle are utilized. These profiles are vertically integrated for the altitude range of 80–100 km and the equivalent column integrated emission rates are then zonally averaged for bins with 10° latitude and 3 month intervals. It is found that for each latitude the O(¹S) nightglow emission rate appears to increase with increasing solar F10.7 cm flux, following a linear relationship. This characterizes the solar cycle impact on the O(¹S) nightglow, while the solar influence is modulated by a seasonal variation. Based on these variations, an empirical formula is derived for predicting the three-month averages of the O(¹S) nightglow integrated emission rate. The standard error of the estimated values from the formula is smaller than 30 Rayleigh.     

利用OH夜气辉反演原子氧数密度时输入参数的不确定度对反演结果的影响

借助OH夜气辉辐射的光化学模式,由OH夜气辉辐射反演中间层-低热层区域的原子氧数密度时,输入参数的不确定性将导致反演得到的原子氧数密度具有不确定性.以在sudden death猝灭模式下通过OH(8-3)振动带体辐射率反演原子氧数密度为例,分别研究了大气参数和OH气辉辐射率的不确定度引起的反演不确定度、化学反应速率常数的不确定度引起的反演不确定度,以及所有输入参数的不确定度共同引起的反演不确定度,找出其不确定度对反演结果影响最大的参数.结果表明,三种反演不确定度均随着高度的升高而增大,温度和体辐射率的不确定度对第一种反演不确定度的贡献最大,反应速率常数b(8)和A(8-3)、的不确定度对第二种反演不确定度的贡献最大.