Superconducting terahertz receivers for space-borne and balloon-borne radio telescopes

A superconducting heterodyne receiver based on superconductor–insulator–superconductor (SIS) junctions and a bolometric receiver based on superconductor–insulator–normal metal (SIN) tunnel junctions developed at the Kotelnikov Institute is described. The noise temperature and noise equivalent power of such a receiver fit the requirements for the TELIS, BOOMERANG, OLIMPO, and LSPE aerostatborne radio telescopes, and the space-based SPICA and MILLIMETRON projects, among others. Applications of such receivers for medical diagnostics and remote control are described.     

Methods for Measuring the Signal of the Phase Calibration of the VLBI Radio Telescopes

Radiophysics and Quantum Electronics - In the majority of modern radio telescopes, which are used for radio interferometry with very long baselines, a special signal is introduced into the signal...     

Telescope illumination and beam measurements for submillimeter astronomy

Submillimeter receivers which operate in the highest frequency atmospheric windows must still be mounted on large infrared and optical telescopes. Finding the optimum submillimeter wave illumination for these large telescopes is simplified by their effectively perfect optical surfaces and long focal lengths, but is complicated by telescope optics which have been optimized for non-tapered beams. In order to determine the effects of changing illumination edge taper, we calculated idealized aperture and beam efficiencies for telescopes which are used for submillimeter astronomical observations. The optimum illumination edge taper for the large infrared telescopes is near 10 dB, somewhat less than for classical radio telescopes, and is not very critical as long as it is between 10 and 13 dB.We also present an accurate method for measuring the sizes of, and deviations from, Gaussian beam pattern distributions by using astronomical sources which have sizes comparable with the beam.     

Millimeter wave radio telescopes: Gain and pointing characteristics

The basic gain and pointing characteristics of millimeter-wave radio telescopes are described in this paper. Formal definitions of relevant telescope parameters are given. Performance limits set by conventional technology are discussed and compared with measurements of existing telescopes. Methods are also suggested for minimizing pointing errors.     

New prospects for astronomy

Astronomers in Britain have until very recently found it hard to obtain observing time on large optical telescopes. The success of observational X-ray and radio astronomy has revealed an urgent need for first-class telescopes on excellent sites. That need is now being met in Australia and at the new observatory on the island of La Palma, where the Royal Greenwich Observatory is providing three telescopes for the Science Research Council. The largest of these, 4.2m in diameter, is to be named the William Herschel Telescope in commemoration of the great telescope builder and observer.     

Recording of ultrahigh-energy astrophysical neutrinos

This review is devoted to the problems of recording ultrahigh-energy neutrinos produced in distant astrophysical sources and during the decay of supermassive particles. Prospects for the detection of neutrino fluxes are considered based on peculiarities of the propagation and interaction of ultrahigh-energy neutrinos. The operating and planned facilities designed to investigate neutrinos from various sources are described: neutrino telescopes recording neutrino interactions in natural water and ice volumes; ground-based arrays of detectors and optical telescopes onboard orbital space stations capable of detecting neutrino-triggered horizontal air showers. Instruments based on new principles of recording neutrinos with extremely high energies are considered: radio telescopes designed to observe Cherenkov radio emission from neutrino cascades originating in such radio-transparent natural environments as the atmosphere, salt domes, ice packs, and lunar regolith; underwater acoustic detectors. It is shown that putting new facilities into operation will allow neutrinos from most of the known astrophysical sources with energies differing by more than ten orders of magnitude, from 10¹² to 10²²–10²⁴ eV, to be recorded.     

空间光学的发展与波前传感技术

摘要：进入21世纪，国际上一些发达国家和有关部门都已制定了空间发展战略规划，如美国航空航天局（NASA）、欧洲空间局（ESA）和俄罗斯政府相关部门等都提出空间发展战略规划，这些规划提出了今后一段时间内空间科学要解决的问题和发展的方向，而解决这些问题并推进空间技术的发展很大程度上依赖于先进的光学和无线电望远镜及仪器设备。因此，本文介绍本世纪初国际上空间科学应用的大型天文望远镜的发展情况，重点描述了大口径光学望远镜的光学系统以及实现这类天文望远镜的关键技术之一一波前传感技术。     

Development of a Radioastronomical Correlation Method for Measuring Mirror-Antenna Parameters

We consider the techniques and instrumentation developed at the Radiophysical Research Institute (NIRFI) for measuring mirror-antenna parameters using signals from extraterrestrial radio sources and geostationary satellites. The results of measuring the radiation patterns of several large-scale fully-rotatory radio telescopes in a wide dynamic range and of retrieving the amplitude and phase distributions on their apertures are presented.     

Problems of cryogenic cooling of superconductor and semiconductor receivers in the range 0.1–1 THz

We present the theoretical fundamentals and features of development of cryogenic cooling systems for receivers in the range 0.1–1 THz. The results of development of cryogenic systems for sustaining the temperatures in the range from 150 to 0.3 K are considered. The systems are based on a wide class of cryogenic devices employing various principles and thermodynamic cycles. The described developments are based on the unity of the thermal and radiophysical complexes of the cooled receiver and the cryosystem. The discussed cryosystems are specifically used to cool receivers with the mixers based on Schottky-barrier diodes and superconductor-insulator-superconductor structures, as well as on various bolometers. The problems of heat insulation against the surrounding medium and heat transfer from the receiver to the cryogenic liquid, the features of the input/output of signals in a wide frequency range and of mechanical vacuum-tight thermo-decoupled inputs to the cryostat, and the control systems for cryoelectronic complexes are considered in detail. The presented results can be used for both laboratory experiments and practical applications in radio astronomy, atmosphere spectroscopy, and other fields.     

开环多普勒技术用于火星快车的观测验证

利用中国甚长基线干涉(very long baseline interferometry,缩写为VLBI)网天线资源以及"嫦娥一号"(Chang'e-1,缩写为CE-1)32星观测试验,首次实现了中国深空任务的开环多普勒测量.这一新的测量技术应用于欧洲航天局(European Space Agency,缩写为ESA)的"火星快车"(Mars Express,缩写为MEX)探测器的观测实验中.实验结果显示,在1s积分情况下,开环多普勒(三程)测量精度随机误差达到1mm/s,这一精度与通常的闭环多普勒(双程)水平相当.开环多普勒(三程)数据已经开始尝试用于卫星的定轨,今后有关开环多普勒数据的科学应用也在准备中.     

Measurement of antenna parameters by signals from space satellites of the GLONASS and Navstar navigation systems

We present the results of experiments on measuring the antenna pattern and alignment of the RT-14 and RT-15 radio telescopes located in the radioastronomy observatories of the Radiophysical Research Institute of Nizhny Novgorod by signals from space satellites of the GLONASS and Navstar navigation systems. The efficiency of using signals of the navigation satellites to measure a number of parameters of the antenna systems is analyzed.     

激光本振红外光谱干涉成像及其艇载天文应用展望(特邀)

本文分析了红外干涉成像现状和难点,介绍了激光本振红外相干探测的原理,阐述了基于电子学的红外光谱细分和干涉成像原理,讨论了激光本振红外阵列探测器形式.激光本振和相干探测器的设置,可保证两个望远镜的红外信号相位的正确传递,在电子学实施窄带滤波形成的窄带红外信号有利于实现长基线干涉成像.在此基础上,类似微波综合孔径射电望远镜...     

用于火星电离层探测的星-星无线电掩星技术

火星和地球类似,周围束缚了不同密度的电离层.利用无线电掩星技术可以对火星电离层进行观测.星-地无线电掩星在探测精度和探测区域方面都受到一定的限制.中俄联合火星探测计划将于2011年10月一箭双星发射俄罗斯的Phobos-Grunt探测器和中国的萤火1号火星探测器.该计划将开展国际上首次火星电离层的星-星无线电掩星观测试验,重点是对星-地无线电掩星无法观测的正午和子夜区域的火星电离层进行探测.星-星无线电掩星观测试验采用双频工作模式,接收机灵敏度为-145dBm,相位测量精度优于5%周.在地面对接收机进行了动态模拟测试,测试得到的相位数据能很好地反演出火星电离层电子密度廓线.     

Holographic optical elements as scanning lidar telescopes

We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. Rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope.     

The effect of radiometric noise on pulsar timing precision

The effect of radio-telescope characteristics on the precision of pulsar timing is studied. We found a definite correlation between the accuracy of long-term pulsar time-series data, instrumental uncertainties of arrival-time timing, and pulsar-flux density. This correlation suggests that modern radio telescopes are still not sensitive enough to investigate the noise that is intrinsic to pulsars or the noise that is due to the propagation of the pulsar signal toward the solar system in the interstellar medium. The next-generation radio telescope, the Square Kilometer Array (SKA), is estimated to have an instrumental uncertainty that will be low enough to be insignificant and not affect the quality of pulsar-timing data.     

Detecting axionlike particles with gamma ray telescopes

We propose that axionlike particles (ALPs) with a two-photon vertex, consistent with all astrophysical and laboratory bounds, may lead to a detectable signature in the spectra of high-energy gamma-ray sources. This occurs as a result of gamma rays being converted into ALPs in the magnetic fields of efficient astrophysical accelerators according to the "Hillas criterion", such as jets of active galactic nuclei or hot spots of radio galaxies. The discovery of such an effect is possible by GLAST in the 1-100 GeV range and by ground-based gamma-ray telescopes in the TeV range.     

Time-crystal ground state and production of gravitational waves from QCD phase transition

We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-peaked gravitational waves signal in the radio frequencies' domain. The signal is an echo of the QCD phase transition that is accessible by planned measurements at the FAST and SKA telescopes.     

Study of an angular radio axis displacement model for 64-meter TNA 1500 radio telescopes (russia)

A model taking into account the technical characteristics of the mechanisms, constructions, and devices of angular control has been developed to standardize systematic angular errors in the guidance system of 64-meter TNA 1500 radio telescopes. To define the structure of the experimental spectrum of systematic errors obtained from the data on the complex radiometric angular standardization of the radio axis, we used an approximation algorithm based on the least squares criterion for the set of functions which follows from the proposed model of corrections. Experimental Design Bureau, Power Engineering Institute, Moscow; Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 11, pp. 1370–1377, November, 1997.     

A 100-GHz-band heterodyne sis receiver for the trao telescope

A 100-GHz-band Superconductor-Insulator-Superconductor (SIS) receiver has been developed for radio astronomy. The mixer used in this receiver has no mechanical tuning elements, such as a backshort or an E-plane tuner. The SIS junction consists of an array of four Nb/Al-AIOx/Nb junctions in series. The quasi-optic system for this receiver has been designed by frequency-independent matching method. The average DSB receiver noise temperature measured in the frequency range from 85 to 115 GHz is 40 K. The receiver is being successfully operated at the Taeduk Radio Astronomy Observatory in Korea.