共查询到20条相似文献,搜索用时 15 毫秒
1.
A. K. Shuaibov 《Technical Physics Letters》1998,24(1):38-40
An investigation is made of the characteristics of a transverse nanosecond discharge in Ne/SF6 and He/Ne/SF6 mixtures at the prebreakdown electron ionization multiplication stage. The conditions needed to obtain a stable transverse
discharge with ultraviolet spark preionization are studied as well as the spectral and temporal characteristics of the plasma
radiation. It is shown that this transverse discharge burning regime may be promising for the selective excitation of neon
atoms which may be used to develop an electric-discharge, λ=585.3 nm, Ne(3s–3p) plasma laser.
Pis’ma Zh. Tekh. Fiz. 24, 85–90 (January 12, 1998) 相似文献
2.
M. Aidaraliev N. V. Zotova S. A. Karandashev B. A. Matveev M. A. Remenny N. M. Stus’ G. N. Talalakin 《Technical Physics Letters》1998,24(6):472-474
The directional patterns, current-voltage characteristics, and spectral characteristics of mesastripe lasers with InGaAsSb
active layers, emitting at λ=3.0–3.6 μm (77 K) and having threshold currents ≥15 mA (j
th≥200 A/cm2), are investigated. The maximum output power is 1.4 mW (λ∼3.3 μm), the differential quantum efficiency ∼3%(τ=5–30 μs, f=500 Hz) for lasing in a longitudinal mode with beam divergences ΔΘ∥∼15° and ΔΘ ⊥ ∼30°. The relationship of the differential
quantum efficiency to the order of the spatial mode of the lasing is demonstrated. A single-mode, current-tunable (−30 cm−1/A) laser is used to measure the transmission of methane in the region of the ν
3 absorption band.
Pis’ma Zh. Tekh. Fiz. 24, 40–45 (June 26, 1998) 相似文献
3.
We have studied the regimes of electric-discharge nonchain HF(DF) lasers using inductive and capacitive energy stores and
determined optimum excitation conditions. On this basis, discharge-initiated HF and DF lasers have been created, which are
characterized by a high specific energy output, high internal efficiency (∼10 and ∼7% of the electric input energy, respectively),
and good technical efficiency (∼6 and ∼5% of the total stored energy, respectively). 相似文献
4.
T. N. Danilova B. E. Zhurtanov A. N. Imenkov M. A. Sipovskaya Yu. P. Yakovlev 《Technical Physics Letters》1999,25(5):395-397
AlGaAsSb lasers with different Al concentrations in the active and confinement regions are fabricated and investigated. The
structures lase in the region ∼1.6 μm. The AlGaAsSb solid solution in the active region is a direct-gap material with a small energy separation (∼56 meV) between
the direct-gap Γ minimum and the indirect-gap L minimum of the conduction band. The lasers have a single-mode spectrum with a predominant longitudinal mode in the spatial
distribution of the emission. The lasers operate at room temperature in a pulsed mode.
Pis’ma Zh. Tekh. Fiz. 25, 35–41 (May 26, 1999) 相似文献
5.
É. N. Abdullin G. P. Bazhenov E. F. Balbonenko S. É. Kunts 《Technical Physics Letters》1998,24(1):79-80
Data on production of electron beams with ∼200 keV electrons and above ∼100 A beam current in a diode with an explosive-emission
cathode at background gas pressures ∼10−2−10−1 torr are presented. Discharge regimes with high-voltage stage duration up to 500–800 ns at 10−2 torr and 80 ns at 10−1 torr have been obtained. The duration of the electron beam behind a 50 μm thick titanium foil was equal to 200 and 400 ns, respectively, and was limited by the transmittance of the foil.
Pis’ma Zh. Tekh. Fiz. 24, 88–92 (January 26, 1998) 相似文献
6.
A. K. Shuaibov A. I. Dashchenko A. A. Sinishin V. S. Shevera 《Technical Physics Letters》1997,23(10):765-766
An investigation is made of the electrical and optical characteristics of a moderate-pressure transverse discharge in typical
active media of infrared CO lasers. The discharge was ignited in a system of unprofiled “ grid-plane” electrodes with automatic
ultraviolet preionization by a corona discharge and had a 2×3 cm aperture. The pulse repetition frequency was 1–10 Hz, the
current pulse length was ≤0.5 μs, and the pressure of the working mixtures was 10–100 kPa. Studies were made of the transverse
discharge current voltage pulses, and also the spectral and temporal characteristics of the plasma radiation in N2:CO, He:N2:CO, and He: N2:CO:Xe mixtures in the ultraviolet and visible ranges.
Pis’ma Zh. Tekh. Fiz. 23, 71–76 (October 12, 1997) 相似文献
7.
In this work, pH dependent evolution of tungsten oxide (WO3) nanostructures is being reported along with physical characteristics. The synthesis was carried out via an inexpensive solvothermal
cum chemical reduction route, with sodium tungstate (Na2WO4) and cetyl trimethyl ammonium bromide (C19H42NBr) as main reactants. The X-ray diffraction, together with transmission electron microscopic studies have revealed formation
of regular polyhedral nanocrystalline structures and fractals as one goes from higher pH (= 5·5) to lower pH (= 2) values.
The average crystallite size, as calculated through Williamson–Hall plots, was varied within 2·8–6·8 nm for different pH samples.
Fourier transform infrared spectroscopy reveals in-plane bending vibration δ (W–OH), observable at ∼1630 cm − 1 and strong stretching ν (W–O–W) located at ∼814 cm − 1. Raman spectroscopy has divulged WO3 Raman active optical phonon modes positioned at ∼717 and 805 cm − 1. The thermochromic and photochromic properties of the nanoscale WO3 sample prepared at pH = 5·5, are also highlighted. 相似文献
8.
The effect of an electron beam and the related plasma on the structure, phase state, and microhardness of the surface of titanium
has been studied in a broad range of beam currents (0.1–2.5 A), electron energies (0.1–1 keV), and gas pressures (0.01–1 Pa).
This range was ensured by the grid stabilization of emissive properties of the plasma electron source, which formed a wide
(∼40 cm2) electron beam in a space charge layer between the beam-excited plasma and the grid bounding the plasma cathode. The sample
temperature (350–900°C) was determined by the electron beam parameters. The plasma density was additionally controlled by
changing the gas (N2 or Ar-N2 mixture) pressure. It is established that, during the low-temperature nitriding process in low-energy electron beam plasma,
the ion sputtering significantly affects the microhardness of a processed surface and the rate of growth of the hardened layer
thickness. The possibility of nitriding at a low (−50 V) or floating potential of the sample eliminates the development of
a surface relief and allows the process to be carried out in deep and narrow slits. 相似文献
9.
The solid-state diffusion bonding was carried out between commercially pure titanium and Type 304 stainless steel using nickel
as an interlayer in the temperature range of 800–900 °C for 9 ks under 3 MPa load in vacuum. The transition joints thus formed
were characterized in the optical and scanning electron microscopes. The inter-diffusion of the chemical species across the
diffusion interfaces were evaluated by electron probe microanalysis. TiNi3, TiNi and Ti2Ni are formed at the nickel–titanium (Ni–Ti) interface; however, the stainless steel–nickel (SS–Ni) diffusion interface is
free from intermetallic compounds up to 850 °C temperature. At 900 °C, the Ni–Ti interface exhibits the presence of α-β Ti
discrete islands in the matrix of Ti2Ni and λ + χ + α-Fe, λ + FeTi and λ + FeTi + β-Ti phase mixtures occur at the SS–Ni interface. The occurrence of different
intermetallics are confirmed by the x-ray diffraction technique. The maximum tensile strength of ∼276 MPa and shear strength
of ∼209 MPa along with 7.3% elongation were obtained for the diffusion couple processed at 850 °C. At the 900 °C joining temperature,
the formation of Fe–Ti base intermetallics reduces the bond strength. Evaluation of the fracture surfaces using scanning electron
microscopy and energy dispersive spectroscopy demonstrates that failure takes place through Ni–Ti interface up to 850 °C and
through the SS–Ni interface of the joint when processed at 900 °C. 相似文献
10.
A. I. Bugrova A. S. Lipatov A. I. Morozov V. K. Kharchevnikov 《Technical Physics Letters》1999,25(6):448-449
Extremely strong low-frequency oscillations (∼35 kHz) predicted earlier were observed experimentally in the channel of a steady-state
plasma thruster. These oscillations are mainly caused by fluctuations of the electron temperature and affect the ion beam
divergence.
Pis’ma Zh. Tekh. Fiz. 25, 64–68 (June 12, 1999) 相似文献
11.
The conditions for formation of nanosize gratings (∼100 nm) of ferromagnetic stripes in the illumination of thin-film (10–15
nm) paramagnetic Fe-Cr mixtures by interfering beams from an excimer laser are investigated. The ferromagnetic ordering arises
as a result of the thermally stimulated clustering of Fe atoms. The gratings are formed in a certain energy interval of the
laser radiation. The width of this interval depends substantially on both the interference period and the illumination time
τ
i. For τ
i=10 ns there exists an energy interval in which gratings with periods as small as 300 nm are formed.
Pis’ma Zh. Tekh. Fiz. 24, 13–20 (June 26, 1998) 相似文献
12.
The structure of a picosecond (∼150 ps) electron beam in the cathode-anode gap of a vacuum diode is determined. The electron
beam is modeled in the form of flat quasiparticles with a definite charge density which follow one after another in equal
time intervals. It is shown that the expansion of concentric layers of the beam under the action of the electric and magnetic
self-fields strongly depends on the current strength. The experimental confirmation of the computed estimates is illustrated
by recording the structure of the electron beam at the anode using a film which is sensitive to electron radiation.
Pis’ma Zh. Tekh. Fiz. 25, 39–45 (September 26, 1999) 相似文献
13.
A. V. Vodop’yanov S. V. Golubev V. G. Zorin S. V. Razin M. A. Shilov 《Technical Physics Letters》1999,25(7):588-589
An experimental investigation is made of x-ray bremsstrahlung in the 2–10 keV range of a pulsed discharge under electron cyclotron
resonance conditions in a straight magnetic mirror system pumped by a high-power millimeter radiation beam. The plasma temperature
and density were determined from the spectrum and intensity of the x-rays. The results indicate that a quasi-gasdynamic plasma
confinement regime is achieved.
Pis’ma Zh. Tekh. Fiz. 25, 90–93 (July 26, 1999) 相似文献
14.
E. A. Grebenshchikova A. M. Litvak V. V. Sherstnev Yu. P. Yakovlev 《Technical Physics Letters》1998,24(8):593-595
An etchant having the composition HCl/CrO3 /HF/H2O is proposed for fabricating optoelectronic devices (lasers, light-emitting diodes, and photodiodes) based on InAs solid
solutions for the 3–5 μm spectral range. It is shown that the proposed etchant ensures isotropic rates of etching of InAs and GaInAsSb, InAsSPbP,
and InAsSb solid solutions of varying composition. An example is given of the use of this etchant to produce high-power light-emitting
diodes for the 3.3 μm spectral range.
Pis’ma Zh. Tekh. Fiz. 24, 27–33 (August 12, 1998) 相似文献
15.
A. K. Shuaibov L. L. Shimon A. I. Dashchenko Yu. Yu. Neimet I. V. Shevera 《Technical Physics Letters》1999,25(6):433-434
Results of optimizing a λ=175 nm ArCl(B-X) emitter pumped by a transverse volume discharge are presented. The formation of
ArCl(B) molecules was investigated in a plasma formed by mixtures of rare gases with HCl and Cl2 molecules. It is shown that the Cl2 molecule is the most efficient chlorine carrier and that neon at pressures ≥ 50 kPa is the most efficient buffer gas.
Pis’ma Zh. Tekh. Fiz. 25, 29–33 (June 12, 1999) 相似文献
16.
V. A. Berezin V. I. Nikolaĭchik V. T. Volkov Yu. B. Gorbatov V. I. Levashov G. L. Klimenko V. A. Tulin V. N. Matveev I. I. Khodos 《Technical Physics Letters》1999,25(5):398-401
Nanobridges are fabricated from lanthanum-strontium anganite deposited on Si3N4 membranes perforated by a focused ion beam. The magnetoresistance is ≈9% in fields of ∼ kOe. Nonlinearity of the current-voltage
characteristic of the bridges is observed, and it is found that the maximum of the resistance is shifted to lower temperatures
from that of a control film sample of composition La0.8Sr0.2MnO3.
Pis’ma Zh. Tekh. Fiz. 25, 42–50 (May 26, 1999) 相似文献
17.
A. A. Bukharaev A. A. Bukharaeva N. I. Nurgazizov D. V. Ovchinnikov 《Technical Physics Letters》1998,24(11):863-865
First results are reported of in situ visualization of the chemical etching of P+-ion implanted SiO2-Si structures in an aqueous HF solution using an atomic force microscope. The rates of SiO2 etching were determined and the kinetics of the photostimulated chemical etching of Si were investigated.
Pis’ma Zh. Tekh. Fiz. 24, 81–86 (November 12, 1998) 相似文献
18.
Yu. P. Sukhorukov N. N. Loshkareva E. A. Gan’shina A. R. Kaul’ O. Yu. Gorbenko K. A. Fatieva 《Technical Physics Letters》1999,25(7):551-554
The absorption spectra of a single-crystal La0.35Pr0.35Ca0.3MnO3 film were studied in the spectral range 0.1–1.6 eV at temperatures between 80 and 295 K. The metal-insulator transition in
the temperature range 160–180K was accompanied by an abrupt increase in the intensity of the transmitted light by a factor
of ∼400. An applied magnetic field of 0.8 T causes a 55% relative change in the intensity near the transition. The prospects
for using these effects to create magnetically controlled optical devices are considered.
Pis’ma Zh. Tekh. Fiz. 25, 6–13 (July 26, 1999) 相似文献
19.
N. S. Ginzburg A. S. Sergeev N. Yu. Peskov A. V. Arzhannikov S. L. Sinitski 《Technical Physics Letters》1999,25(10):796-799
It is shown that two-dimensional doubly-periodic Bragg structures can be used effectively in the amplification schemes of
free electron lasers powered by sheet relativistic electron beams. The presence of such a structure ensures spatial coherence
of radiation from different parts of the electron beam when the input signal propagates across the electron flux. Theoretical
analysis shows that the gain in the regenerative scheme can reach 50 dB.
Pis’ma Zh. Tekh. Fiz. 25, 87–95 (October 12, 1999) 相似文献
20.
A scheme enabling spatial matching of copper-vapor laser radiation, which pumps a mode of an Al2O3:Ti laser cavity, has been developed and implemented. It is shown that copper vapor lasers as pump sources for titanium-sapphire
lasers are fully capable of competing with conventional pump sources.
Pis’ma Zh. Tekh. Fiz. 25, 6–11 (September 26, 1999) 相似文献