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1.
We have developed and tested a gyroklystron operating with the second harmonic of the electron cyclotron frequency at a frequency
of 32.3 GHz in the field of a permanent magnet. In the two-and three-cavity versions of the gyroklystron, the peak power of
the output radiation reached 320 kW with an efficiency of 30%, an amplification coefficient of 20–25 dB, and an operating
frequency bandwidth of 0.05%. In the wide-band version of the gyroklystron, the amplification bandwidth was equal to 0.27%
for an output power of 200 kW and an amplification coefficient of 13 dB. 相似文献
2.
M. Yu. Glyavin A. G. Luchinin M. V. Morozkin V. I. Khizhnyak 《Radiophysics and Quantum Electronics》2008,51(1):57-63
We present the calculation results for the bandwidth of smooth mechanical tuning of the generation frequency in a gyrotron
with a coaxial cavity. The tuning is based on moving a cone-shaped coaxial rod along the device axis to vary the eigenfrequencies
of the cavity. The use of an internal conductor with an impedance surface allows reducing the thermal load on it. The calculation
results show that it is possible to tune the operating frequency of the oscillator by 3–4% at frequencies up to 330 GHz for
an output power of about 10 kW in the continuous-wave operation regime.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 1, pp. 63–70, January 2008. 相似文献
3.
Numerical modelling is used to study the effect of tuning the laser output over the gain bandwidth on the modulation response
of GaInAs–GaInAsP quantum-well heterolasers for different modulation frequencies of the pump current. It is found that the
maximum frequency bandwidth of the response band and the greatest feasibility of high speed modulation for transmission of
signals in information systems are achieved in the center of the gain band. Raising the dc component of the pump current increases
the response bandwidth. For typical parameters of this system (near 1.5 μm) the maximum response bandwidth can approach ≈40
GHz. For certain parameters, the amplitude-frequency characteristics of the heterolasers have two local maxima: one at low
frequency corresponding usually to a resonance for the 1/2 subharmonic and one at high frequency, for the fundamental resonance. 相似文献
4.
5.
Xiaoqiang Xie Chengxi Zhao Rui Diao 《International Journal of Infrared and Millimeter Waves》2008,29(9):862-870
This paper presents a new millimeter-wave solid-state power combining amplifier, which is based on a waveguide-microstrip
E-plane dual-probe four-way power combining network. With a compact structure and an easy fabrication process, this combining
network fulfils waveguide-to-microstrip transition and power combining simultaneously, and shows a broad-band low loss performance
in Ka-band. With good thermal property, a four-way high power combining amplifier is fabricated. The measured output power
is more than 40 dBm in 32–37 GHz, and the highest output power, 15.8 W, occurs at 32 GHz. The corresponding combining efficiency
is more than 77% in 32–38 GHz. 相似文献
6.
V. E. Zapevalov V. K. Lygin O. V. Malygin M. A. Moiseev V. I. Khizhnyak V. P. Karpov E. M. Tai T. Idehara S. Mitsudo I. Ogawa T. Saito 《Radiophysics and Quantum Electronics》2007,50(6):420-428
We consider a general concept of construction, the possible versions, and specific features of a gyrotron, whose output power
in CW oscillation regime can reach a few kilowatts at a frequency of 300 GHz. The gyrotron is designed for work in a high-frequency
facility in combination with a “dry” cryomagnet, which ensures a magnetic field of up to 12 T, required for the gyrotron operation.
The basic results of numerical simulation and optimization of the electron gun, the resonant cavity, and other subsystems
of the gyrotron are presented. The designs used for the gyrotron development are justified. Preliminary experiments showed
the efficiency of the pilotproduction gyrotron with an output power of about 2 kW, which is record-breaking in this frequency
range.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 6, pp. 461–470, June 2007. 相似文献
7.
V. E. Zapevalov Yu. K. Kalynov V. K. Lygin O. V. Malygin S. A. Malygin M. A. Moiseev V. N. Manuilov E. A. Soluyanova E. M. Tai V. I. Khizhnjak 《Radiophysics and Quantum Electronics》2006,49(3):185-195
A number of experimental plasma devices require high-power sources of electromagnetic radiation in a range of 5 to 30 GHz.
In this paper, we consider gyrotrons as such sources. The difficulties of creating long-wavelength gyrotrons are discussed
and the possibility to overcome them is shown for already existing and currently developed oscillators. We present the results
of studies aimed at development of high-power, long-pulse, low-frequency gyrotrons in Russia, as well as the designs and performance
parameters of industrial gyrotrons operated at frequencies 5 and 28 GHz with an output power of 0.5 MW. Several design versions
of the gyrotrons with operating frequencies 17.5 and 28 GHz, an output power of up to 1 MW, and a pulse duration of up to
5 s are discussed and the design features which make it possible to overcome the difficulties of their manufacturing are considered.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 207–218, March 2006. 相似文献
8.
We study the scattering of electromagnetic radiation by structural inhomogeneities of CVD diamond windows used to output the
power produced by megawatt gyrotrons in the 100–1000 GHz range. It is shown that the scattering can make a significant contribution
to the attenuation of the radiation starting from 200 GHz, and becomes a determinant factor near 1 THz. Even in the framework
of the single-scattering approximation, about one-third of the scattered power is released beyond the window.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 12, pp. 1048–1057, December 2007. 相似文献
9.
Sh. D. Kitai 《Radiophysics and Quantum Electronics》1999,42(3):211-215
We analyze the characteristics of radio emission from the middle atmosphere during limb sounding of minor gas constituents
with rotational transitions of the molecules located in the atmospheric transparency windows 105–118 GHz and 180–210 GHz.
Optimal frequencies and height ranges for the sounding of minor gases are found by numerical modeling for typical values of
the receiver bandwidth.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 42, No. 3, pp. 235–239, March 1999. 相似文献
10.
Liang Kui Sun Hai Feng Cheng Yong Jiang Zhou Jun Wang 《Applied Physics A: Materials Science & Processing》2011,105(1):49-53
We report a metamaterial absorber (MA) with a broad absorption band in the frequency region of 2–4 GHz, whose thickness is
not limited to the quarter-wavelength. Theoretical and experimental results show that the absorber has two adjacent absorption
apexes at 2.24 and 3.46 GHz, respectively, which are both related to the electric and magnetic resonances of the metamaterial.
The absorption is over 68% in the whole wave band of 2–4 GHz provided the thickness of 4 mm. The distributions of the surface
currents and the power loss density indicate that the surface currents produced by the electric and magnetic resonances are
strongly consumed by the resistive patches. This low-frequency absorber has potential applications in many scientific and
martial fields. 相似文献
11.
An interest in energy transport in 3D chains of metal nanoparticles is oriented towards future applications in nanoscale optical
devices. We consider plasmonic waveguides composed of silver nanoplates arranged in several geometries to find the one with
the lowest attenuation. We investigate light propagation of 500-nm wavelength along different chains of silver nanoplates
of subwavelength length and width and wavelength-size height. Energy transmission of the waveguides is analysed in the range
of 400–2000 nm. We find that chain of short parallel nanoplates guides energy better than two electromagnetically coupled
continuous stripes and all other considered nonparallel structures. In a wavelength range of 500–600 nm, this 2-μm long 3D
waveguide transmits 39% of incident energy in a channel of λ × λ/2 cross section area. 相似文献
12.
B. Cocquelin D. Holleville G. Lucas-Leclin I. Sagnes A. Garnache M. Myara P. Georges 《Applied physics. B, Lasers and optics》2009,95(2):315-321
We report on a diode-pumped vertical external-cavity surface-emitting laser emitting around 852 nm for Cesium atomic clocks
experiments. We have designed a 7-quantum-well semiconductor structure optimized for low laser threshold. An output power
of 330 mW was achieved for 1.1 W of incident pump power. Furthermore, a compact setup was built for low-power single-frequency
emission. We obtained an output power of 17 mW in a single longitudinal mode, exhibiting both broad (9 nm) and continuous
(14 GHz) tunability around the Cesium D2 line. The laser frequency has been stabilized on an atomic transition with residual frequency fluctuations ∼300 kHz. Through
a beatnote experiment the −3 dB laser linewidth has been measured to <500 kHz over 10 ms. 相似文献
13.
B. Köhler U. Bäder A. Nebel J.-P. Meyn R. Wallenstein 《Applied physics. B, Lasers and optics》2002,75(1):31-34
We report on an injection-seeded 9.5-W 82-MHz-repetition-rate picosecond optical parametric generator (OPG) based on a 55 mm
long crystal of periodically poled lithium niobate (PPLN) with a quasi-phase-matching (QPM) grating period of 29.75 μm. The
OPG is excited by a continuously diode pumped mode-locked picosecond Nd:YVO4 oscillator-amplifier system. The laser system generates 7 ps pulses with a repetition rate of 82.3 MHz and an average power
of 24 W. Without injection-seeding the total average output power of the OPG is 8.9 W, which corresponds to an internal conversion
efficiency of 50%. The wavelengths of the signal and idler waves were tuned in the range 1.57–1.64 μm and 3.03–3.3 μm, respectively,
by changing the crystal temperature from 150 °C to 250 °C. Injection seeding of the OPG at 1.58 μm with 4 mW of single frequency
continuous-wave radiation of a distributed-feedback (DFB) diode laser increases the OPG output to 9.5 W (53% conversion efficiency).
The injection seeding increases the pulse duration and reduces the spectral bandwidth. When pumped by 10 W of 1.06 μm laser
radiation, the duration of the signal pulses increased from 3.6 ps to 5.5 ps while the spectral bandwidth is reduced from
4.5 nm to 0.85 nm. Seeding thus improved the time-bandwidth product from 1.98 to a value of 0.56, much closer to the Fourier
limit.
Received: 29 April 2002 / Published online: 8 August 2002 相似文献
14.
We obtained some exact expressions for the power of the output signal of adaptive systems with continuous gradient adjustment
algorithms. It is shown that fluctuations of weight coefficients result in a decrease in the signal power at the adaptive-system
output as compared with the output-signal power in the absence of fluctuations of the weight coefficients. The “overcompensation”
phenomenon is explained by the presence of a non-Gaussian statistical relation between the weight- coefficient and input-signal
vectors.
N. I. Lobachevskii State University, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 42, No. 9, pp. 914–921, September, 1999. 相似文献
15.
We examine both theoretically and experimentally the possibility of miniaturization of planar microstrip dipole antennas of
small electric dimensions. The antennas are made from high-temperature superconductors. The dependence of the matching conditions
and the bandwidth on the design and geometrical features of the antennas is analyzed. It is shown that a superconductor antenna
of size L≅(0.05–0.1)λ can have about 100% efficiency and a bandwidth of 0.2–2%. We propose a miniature microstrip antenna
of dimensions 11 mm×11 mm for the frequency band 1.3 GHz. Measurements of the radio characteristics of the copper mockup of
the antenna confirmed the efficiency of the optimization.
Radiophysical Research Institute, Institute of Physics of Microstructures of the Russian Academy of Sciences, Nizhny Novgorod,
Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 2, pp. 158–167, February 1999. 相似文献
16.
针对高功率固态源多路功率分配技术的需要,设计并研究了一种基于同轴波导的多路功率分配器件。通过分析同轴波导传输特性与阻抗匹配理论,利用电磁仿真软件设计了一种S波段1分16功分器模型,并加工出实物进行实验测试。实验结果表明:该功分器在2.28~2.86 GHz,相对带宽约23%频率范围内,输入端反射系数S11≤-15 dB;在2.37~2.57 GHz,相对带宽约8.1%频率范围内,输入端反射系数S11≤-20 dB;输出幅度不平衡度±0.1 dB,相位不平衡度±5°。该功分器满足输出幅度与相位一致性要求,可应用于S波段百瓦级连续波功率分配。 相似文献
17.
Single axial mode operation (<200 MHz optical bandwidth) of a high repetition rate periodically poled lithium niobate optical
parametric oscillator (OPO) has been obtained at signal wavelengths between 1.46 μm and 1.64 μm. OPO signal slope efficiencies
of 35% have been measured for repetition rates of 5–20 kHz. Single mode operation required spectral narrowing of both the
pump laser and the OPO. A simple technique of prelase Q-switching was implemented to reduce the optical bandwidth of the cw diode-pumped Nd:YAG pump laser to <1 GHz. A single intracavity
étalon was then sufficient to ensure single frequency oscillation of the OPO signal. The OPO output was stable with a smooth
spatial profile and an M
2 value of 1.3.
Received: 29 September 1999 / Published online: 27 January 2000 相似文献
18.
A study is made of the production of high power nanosecond rf pulses by extracting microwave energy from an oversized cavity
by means of conversion, at a coupling window, of the high-Q working mode to an auxiliary mode which is strongly coupled to
an external load. It is shown that microwave rf pulse compressors with copper storage cavities and energy extraction by mode
conversion at a coupling window can provide gains of 5–13 dB with output signal durations of 20–150 ns and peak powers of
5–10 MW in the 3-cm band and 50–100 MW in the 10-cm band. Rf pulses lasting 30 ns with peak powers of 0.5 MW have been obtained
experimentally at a frequency of 9.4 GHz with a gain of 9 dB.
Zh. Tekh. Fiz. 68, 92–96 (July 1998) 相似文献
19.
We analyze a recently proposed technique for fast acquisition of the two-dimensional (2D) spatial distribution of reflectance
spectra to figure out how much its ability of distinguishing almost similar spectra declines with increase of the spectral
line bandwidth of the light source. This analysis was carried out using the experimentally measured reflectance spectra of
four metameric samples and simulating the system response to an illumination by spectral lines with variable bandwidth. It
was shown that the metameric samples are distinguishable even when the bandwidth of illuminating lines is 20–30 nm. A wider
bandwidth allows implementation of simultaneous illumination of an object that leads to a diminution of the acquisition time
of 2D-multispectral images due to both faster operation in the parallel mode of Light-emitting diodes (LEDs) switching and
higher output power. 相似文献
20.
H. C. Liang H. L. Chang W. C. Huang K. W. Su Y. F. Chen Y. T. Chen 《Applied physics. B, Lasers and optics》2009,97(2):451-455
The large third-order nonlinearity of GdVO4 crystals is employed to realize the compact efficient continuous-wave self-mode locking in the range of several GHz in a
Nd:GdVO4 laser with a simple linear cavity without the need of any additional components. With a pump power of 2.5 W, the compact
laser cavity produces average output powers greater than 0.7 W with a pulse width as short as 23 ps in the range of 2–6 GHz. 相似文献