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Author Ожегов, Р.В.; Окунев, О.В.; Гольцман, Г.Н. openurl 
  Title Флуктуационная чувствительность сверхпроводящего болометрического смесителя на эффекте разогрева электронного газа Type Journal Article
  Year 2009 Publication Радиотехника Abbreviated Journal (up)  
  Volume Issue 3 Pages 120-124  
  Keywords смеситель на горячих электронах; флуктуационная чувствительность; тепловизор терагерцевого диапазона частот; hot-electron bolometer mixer; Imaging system; Noise equivalent temperature difference; Heterodyne receiver; Terahertz range  
  Abstract Interest in research in the terahertz range is driven by a great number of various applications, where terahertz instruments may play a leading role. To name just a few, such applications include study of the cosmic microwave background radiation and the distribution of the dark matter, medicine, navigation, fire alarm, security systems and environmental monitoring. The paper discusses the possibility of using a receiver based on the hot-electron effect in superconducting films as an imaging system. We present the results of the noise equivalent temperature difference (NETD) measurements performed with a hot-electron bolometer mixer made from a thin superconducting film. The receiver with a noise temperature of ~ 3800 K at a local oscillator frequency of 300 GHz a bandwidth of 500 MHz and an integration time of 1 s has offered an NETD of 0.5 K. We have also developed a technique that enabled us to reduce the contribution of the mixer gain fluctuations to the overall system instability. As of this writing, the above value of the NETD is the lowest value offered for this type of receiver, which indicates the possibility to use such receivers in real-time imaging systems. The technique offered in the paper for achieving the limiting value of the NETD offers an alternative to the phase-locking scheme.

Представены результаты измерения флуктуационной чувствительности (NETD – noise equivalent temperature difference) болометрического смесителя на эффекте разогрева электронного газа в тонких сверхпроводящих пленках. Получено предельное значение NETD, равное 0,5 К, при шумовой температуре приемника 3800 К, ширине полосы преобразования 500 МГц, постоянной времени 1 с и частоте гетеродина 300 ГГц. Разработана методика достижения предельной флуктуационной чувствительности, позволяющая избежать влияния нестабильности коэффициента преобразования смесителя.
 
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  Call Number RPLAB @ gujma @ Serial 728  
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Author Khosropanah, Pourya openurl 
  Title NbN and NbTiN hot electron bolometer THz mixers Type Book Whole
  Year 2003 Publication Chalmers University of Technology Abbreviated Journal (up)  
  Volume Issue Pages  
  Keywords HEB mixer, hot electron bolometer mixer, NbN, NbTiN, superconducting detector, heterodyne receiver, THz mixer, submillimeter mixer, quasioptical receiver, double slot antenna, twin slot antenna, spiral antenna, receiver noise, FTS, Fourier Transform Spectrometer  
  Abstract The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (â‰<a4>5 nm). They are integrated with wideband spiral or double-slot planar antennas. The mixer chips are incorporated into a quasi-optical receiver. The experimental part of this work focuses on the characterization of the receiver as a whole, and the HEB mixers as a part. Double side band receiver noise temperature and the IF bandwidth are reported for frequencies from 0.7 THz up to 2.6 THz. The spectrum of the direct response of HEB integrated with dierent antennas are measured using Fourier Transform Spectrometer (FTS). The effect of the bolometer size on total receiver performance and the LO power requirements is also discussed. A high-yield and reliable process for fabrication of NbN HEB mixers have been achieved. Over 100 devices with different bolometer geometry, film property and also different antennas have been fabricated and measured. The measured data enables us to discuss the impact of different parameters to the receiver overall performance.

This work has provided NbN HEB mixers to the following receivers:

TREND (Terahertz REceiver with NbN HEB Device) operating at 1.25-1.5 THz, installed in AST/RO Submillimeter Wave Telescope, Amundsen/Scott South Pole Station, in 2002-2003.

Band 6-low (1.410-1.700 THz) and 6-high (1.700-1.920 THz) of the HIFI (Heterodyne Instrument for Far Infra-red) in the Herschel Space Observatory, due to launch in 2007 by ESA (European Space Agency).

Besides, there has been continuous efforts to develop better models to explain the mixer performance more accurately. They are based on two temperature model for electrons and phonons and solving one-dimensional heat balance equations along the bolometer. The principles of these models are illustrated and the calculated results are compared with measured data.
 
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  Corporate Author Thesis Ph.D. thesis  
  Publisher Chalmers University of Technology Place of Publication Göteborg Editor  
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  Notes Approved no  
  Call Number Serial 910  
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Author Hoevers, H. F. C.; Bento, A. C.; Bruijn, M. P.; Gottardi, L.; Korevaar, M. A. N.; Mels, W. A.; de Korte, P. A. J. openurl 
  Title Thermal fluctuation noise in a voltage biased superconducting transition edge thermometer Type Journal Article
  Year 2000 Publication Applied Physics Letters Abbreviated Journal (up) Appl. Phys. Lett.  
  Volume 77 Issue 26 Pages 4421-4424  
  Keywords TES; bolometer; thermal fluctuation noise; TFN  
  Abstract The current noise at the output of a microcalorimeter with a voltage biased superconducting transition edge thermometer is studied in detail. In addition to the two well-known noise sources: thermal fluctuation noise from the heat link to the bath and Johnson noise from the resistive thermometer, a third noise source strongly correlated with the steepness of the thermometer is required to fit the measured noise spectra. Thermal fluctuation noise, originating in the thermometer itself, fully explains the additional noise. A simple model provides quantitative agreement between the observed and calculated noise spectra for all bias points in the superconducting transition.  
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  Call Number RPLAB @ gujma @ Serial 759  
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Author Bennett, Douglas A.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N. doi  openurl
  Title Phase-slip lines as a resistance mechanism in transition-edge sensors Type Journal Article
  Year 2014 Publication Appl. Phys. Lett. Abbreviated Journal (up) Appl. Phys. Lett.  
  Volume 104 Issue Pages 042602  
  Keywords microbolometers, TES, phase-slip lines, PSL  
  Abstract The fundamental mechanism of resistance in voltage-biased superconducting films is poorly understood despite its importance as the basis of transition-edge sensors (TESs). TESs are utilized in state-of-the-art microbolometers and microcalorimeters covering a wide range of energies and applications. We present a model for the resistance of a TES based on phase-slip lines (PSLs) and compare the model to data. One of the model's predictions, discrete changes in the number of PSLs, is a possible explanation for the observed switching between discrete current states in localized regions of bias.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 929  
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Author Maslennikov, S. url  openurl
  Title RF heating efficiency of the terahertz superconducting hot-electron bolometer Type Journal Article
  Year 2014 Publication arXiv Abbreviated Journal (up) arXiv  
  Volume 1404.5276 Issue Pages 1-4  
  Keywords superconducting hot-electron bolometer mixer, HEB, NbN, distributed model, HEB model, HEB mixer model, heat balance equa-tions, conversion gain, RF heating efficiency, noise temperature, simulation, Euler method  
  Abstract We report results of the numerical solution by the Euler method of the system of heat balance equations written in recurrent form for the superconducting hot-electron bolometer (HEB) embedded in an electrical circuit. By taking into account the dependence of the HEB resistance on the transport current we have been able to calculate rigorously the RF heating efficiency, absorbed local oscillator (LO) power and conversion gain of the HEB mixer. We show that the calculated conversion gai nis in excellent agreement with the experimental results, and that the substitution of the calculated RF heating efficiency and absorbed LO power into the expressions for the conversion gain and noise temperature given by the analytical small-signal model of the HEB yields excellent agreement with the corresponding measured values  
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  Notes Approved no  
  Call Number RPLAB @ atomics90 @ Serial 954  
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