| Home | [31–40] << 41 42 43 44 45 46 47 48 49 50 >> [51–60] |
|
| Records | |||||
|---|---|---|---|---|---|
Author  |
Karasik, B. S.; Il'in, K. S.; Ptitsina, N. G.; Gol'tsman, G. N.; Gershenzon, E. M.; Pechen', E. V.; Krasnosvobodtsev, S. I. | ||||
| Title | Electron-phonon scattering rate in impure NbC films | Type | Abstract | ||
| Year | 1998 | Publication | NASA/ADS | Abbreviated Journal | NASA/ADS |
| Volume | Issue | Pages | Y35.08 | ||
| Keywords | NbC films | ||||
| Abstract | The study of the electron-phonon interaction in thin (20 nm) NbC films with electron mean free path l=2-13 nm gives an evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference ~T^2-term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5 – 10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence T^n with the exponent n = 2.5-3. This behaviour is well explained by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | American Physical Society, Annual March Meeting, March 16-20, 1998 Los Angeles, CA | ||
| Notes | Approved | no | |||
| Call Number | Serial | 1591 | |||
| Permanent link to this record | |||||
| Author |
Karasik, B. S.; Elantiev, A. I. | ||||
| Title | Analysis of the noise performance of a hot-electron superconducting bolometer mixer | Type | Conference Article | ||
| Year | 1995 | Publication | Proc. 6th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 6th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 229-246 | ||
| Keywords | HEB mixers | ||||
| Abstract | A theoretical analysis for the noise temperature of hot–electron superconducting mixer has been presented. Thecontributions of both Johnson noise and electron temperature fluctuations have been evaluated. A set of criteriaensuring low noise performance of the mixer has been stated and a simple analytic expression for the noisetemperature of the mixer device has been suggested. It has been shown that an improvement of the mixer sensitivitydoes not necessarily follow by a decrease of the bandwidth. An SSB noise temperature limit due to the intrinsic noisemechanisms has been estimated to be as low as 40–90 K for a mixer device made from Nb or NbN thin film.Furthermore, the conversion gain bandwidth can be as wide as is allowed by the intrinsic electron temperaturerelaxation time if an appropriate choice of the mixer resistance has been made. The intrinsic mixer noise bandwidthis of 3 GHz for Nb device and of 5 GHz for NbN device. An additional improvement of the theory has been madewhen a distinction between the impedance measured at high intermediate frequency (larger than the mixerbandwidth) and the mixer ohmic resistance has been taken into account.Recently obtained experimental data on Nb and NbNbolometer mixer devices are viewed in connection with thetheoretical predictions.The noise temperature limit has also been specified for the mixer device where an outdiffusion coolingmechanism rather than the electron–phonon energy relaxation determines the mixer bandwidth. A consideration ofthe noise performance of a bolometer mixer made from YBaCuO film utilizing a hot–electron effect has been done. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Pasadena, Ca | Editor | ||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 258 | |||
| Permanent link to this record | |||||
| Author |
Jiang, Ling; Miao, Wei; Zhang, Wen; Li, Ning; Lin, Zhen Hui; Yao, Qi Jun; Shi, Sheng-Cai; Svechnikov, Sergey I.; Vakhtomin, Yury B.; Antipov, Sergey V.; Voronov, Boris M.; Kaurova, Natalia S.; Gol'tsman, Gregory N. | ||||
| Title | Characterization of quasi-optical NbN phonon-cooled superconducting HEB mixers | Type | Conference Article | ||
| Year | 2006 | Publication | Proc. 17th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 17th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 55-58 | ||
| Keywords | NbN HEB mixers | ||||
| Abstract | In this paper, we thoroughly investigate the performance of quasi-optical NbN phonon-cooled superconducting hot-electron bolometer (HEB) mixers, cryogenically cooled by a close-cycled 4-K refrigerator at 500 GI-1z and 850 GHz. The uncorrected lowest receiver noise Abstract---In temperatures measured are 800 K at 500 CHz without anti-reflection coating, and 1000 K @ 850 GHz with a 50 11M thick Mylar anti-reflection coating. The dependence of receiver noise temperature on the critical current and bath temperature of HEB mixer is also investigated here. Lifetime of quasi-optical superconducting NbN HEB mixers of different volumes, room temperature resistances, and critical temperatures are thoroughly studied. Increased room temperature resistance with time over the initial resistance changes between 1 and 1.2, and the reduced critical current with time over the initial value fluctuates slightly around 0.7 for most HEB mixers even of different volumes, room temperature resistances, and critical temperatures. The critical current degrades sharply vvhile room temperature resistance varies over 1.25. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1435 | |||
| Permanent link to this record | |||||
| Author |
Jiang, L.; Zhang, W.; Yao, Q. J.; Lin, Z. H.; Li, J.; Shi, S. C.; Svechnikov, S. I.; Vachtomin, Y. B.; Antipov, S. V.; Voronov, B. M.; Kaurova, N. S.; Gol'tsman, G. N. | ||||
| Title | Characterization of a quasi-optical NbN superconducting hot-electron bolometer mixer | Type | Conference Article | ||
| Year | 2005 | Publication | Proc. PIERS | Abbreviated Journal | Proc. PIERS |
| Volume | 1 | Issue | 5 | Pages | 587-590 |
| Keywords | NbN HEB mixers | ||||
| Abstract | In this paper, we report the performance of a quasi-optical NbN superconducting HEB (hot electron bolome-ter) mixer measured at 500 GHz. The quasi-optical NbN superconducting HEB mixer is cryogenically cooled bya 4-K close-cycled refrigerator. Its receiver noise temperature and conversion gain are thoroughly investigatedfor different LO pumping levels and dc biases. The lowest receiver noise temperature is found to be approxi-mately 1200 K, and reduced to about 445 K after correcting theloss of the measurement system. The stabilityof the mixer’s IF output power is also demonstrated. | ||||
| Address | Hangzhou, China | ||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1931-7360 | ISBN | Medium | ||
| Area | Expedition | Conference | Progress In Electromagnetics Research Symposium | ||
| Notes | Approved | no | |||
| Call Number | Serial | 1482 | |||
| Permanent link to this record | |||||
| Author |
Iomdina, E. N.; Seliverstov, S.; Sianosyan, A.; Teplyakova, K.; Rusova, A.; Goltsman, G. | ||||
| Title | The prospects of using the radiation for the assessment of corneal and scleral hydration | Type | Abstract | ||
| Year | 2016 | Publication | Acta Ophthalmol. | Abbreviated Journal | Acta Ophthalmol. |
| Volume | 94 | Issue | Pages | ||
| Keywords | BWO, avalanche transit‐time diode, medicine, biology | ||||
| Abstract | Purpose An adequate water balance (hydration extent) is one of the basic factors of normal eye function, including its external shells – the cornea and the sclera. THz systems creating images in reflected beams are likely to become ideal instruments of noninvasive testing of corneal and scleral hydration degree as THz radiation is highly sensitive to water content. The paper aims at studying the transmittance and reflectance spectra of the cornea and the sclera of rabbit and human eyes, as well as those of the whole rabbit eye, in the frequency range of 0.13–0.32 THz. Methods The experiments were carried out on 3 corneas and 3 rabbit scleras, 2 whole rabbit eyes, and 3 human healthy adult scleras using a specially developed THz system based on reliable and easy‐to‐use continuous wave sources: a backward‐wave oscillator and an avalanche transit‐time diode. Results The transmittance spectra of the cornea and the sclera and the dependence of the reflection coefficient of these tissues in THz range on water percentage content were determined. Comparison of the rabbit cornea hydrated from 73.2% to 76.3% concentration by mass demonstrated an approximately linear relationship between THz reflectivity and water concentration. The decrease of free water concentration by 1% leads to a drop of the reflectance coefficient by 13%. The parameters studied displayed noticeable differences between the sclera and the cornea of rabbits and between rabbit sclera and human sclera. Conclusions Preliminary results demonstrate that the proposed technique, based on continuous THz radiation, may be used to create a device for noninvasive testing of corneal and scleral hydration, which has good potential of wide‐scale practical application. The work was supported by the Russian Foundation of Basic Research (grant No.15‐29‐03843) |
||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1755375X | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1333 | |||
| Permanent link to this record | |||||