排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
K. S. Volodin I. M. Minaev A. A. Rukhadze K. Z. Rukhadze K. F. Sergeichev 《Plasma Physics Reports》2009,35(1):50-53
The possibility of controlling the directional pattern of a multislot waveguide antenna with the help of a gas-discharge tube placed inside the waveguide was studied experimentally. Since the dielectric parameters of the waveguide depend on the plasma density in the discharge column, they can be controlled by varying the discharge current. The high efficiency of such plasma control was demonstrated experimentally: as the discharge current was varied from 0 to 200 mA, the antenna directional pattern turned by ~17°. 相似文献
2.
It is demonstrated experimentally that the lifetime of the afterglow plasma of a high-current pulsed discharge in a dielectric
tube filled with a mixture of argon with saturated mercury vapor is longer than 1 ms. Such a long lifetime, during which the
electron density decreases from 1014 to 1012 cm−3, is explained by the chemi-ionization of mercury vapor by long-lived metastable argon atoms. During this time, the afterglow
plasma can serve as a microwave waveguide for a weakly damped low-noise E
0-type axisymmetric surface mode, which allows one to use it for transmission of signals in the centimeter wavelength range. 相似文献
3.
Sergeichev K. F. Lukina N. A. Bolshakov A. P. Ralchenko V. G. Arutyunyan N. R. Vlasov I. I. 《Plasma Physics Reports》2010,36(13):1272-1277
Diamond films of different structures were deposited on quartz, WC-Co, and molybdenum substrates in a microwave plasma torch
discharge in an argon-hydrogen-methane gas mixture in a sealed chamber at pressures close to atmospheric by using the chemical
vapor deposition technique. Images of diamond polycrystal films and separate crystals, as well as results of Raman spectroscopy,
are presented. The spectra of optical plasma radiation recorded during film deposition demonstrate the presence of intense
Hα hydrogen and C2 radical bands known as Swan bands. 相似文献
4.
Results are presented from experiments on the acceleration of electrons by a 2.45-GHz microwave field in an adiabatic mirror trap under electron cyclotron resonance conditions, the electric and wave vectors of the wave being orthogonal to the trap axis. At a microwave electric field of ≥10 V/cm and air pressures of 10?6–10?4 Torr (the experiments were also performed with helium and argon), a self-sustained discharge was initiated in which a fraction of plasma electrons were accelerated to energies of 0.3–0.5 MeV. After the onset of instability, the acceleration terminated; the plasma decayed; and the accelerated electrons escaped toward the chamber wall, causing the generation of X-ray emission. Estimates show that electrons can be accelerated to the above energies only in the regime of self-phased interaction with the microwave field, provided that the electrons with a relativistically increased mass penetrate into the region with a higher magnetic field. It is shown that the negative-mass instability also can contribute to electron acceleration. The dynamic friction of the fast electrons by neutral particles in the drift space between the resonance zones does not suppress electron acceleration, so the electrons pass into a runaway regime. Since the air molecules excited by relativistic runaway electrons radiate primarily in the red spectral region, this experiment can be considered as a model of high-altitude atmospheric discharges, known as “red sprites.” 相似文献
5.
It is shown that, in a microwave torch discharge in an argon jet injected into an oxygen atmosphere at normal pressure, quasi-resonant energy transfer from metastable argon atoms to molecules of oxygen and ozone generated in the torch shell and, then, to oxygen atoms produced via the dissociation of molecular oxygen and ozone leads to the inverse population of metastable levels of atomic oxygen. As a result, the excited atomic oxygen with population inversions becomes a gain medium for lasing at wavelengths of 844.6 and 777.3 nm (the 33 P–33 S and 35 P–35 S transitions). It is shown that an increase in the ozone density is accompanied by an increase in both the lasing efficiency at these wavelength and the emission intensity of the plasma-forming argon at a wavelength of 811.15 nm (the 2 P 04s–2 P 04p transition). When the torch operates unstably, the production of singlet oxygen suppresses ozone generation; as a result, the lasing effect at these wavelengths disappears. 相似文献
6.
Plasma Physics Reports - Propagation was studied of the ionization front of the gas discharge sustained by the microwave surface wave in a quartz tube filled with low-pressure air. In a wide... 相似文献
7.
E. N. Istomin D. M. Karfidov I. M. Minaev A. A. Rukhadze V. P. Tarakanov K. F. Sergeichev A. Yu. Trefilov 《Plasma Physics Reports》2006,32(5):388-400
A study is made of a quarter-wave asymmetric dipole antenna in which the conducting rod is replaced by a plasma column with an electron density much higher than the critical density. The parameters of such an antenna are determined by the exited surface wave, which affects the electromagnetic field structure in the near-field zone. It is shown analytically, numerically, and experimentally that the resonant length of the plasma dipole antenna is close to one-quarter of the length of the surface wav and that the conversion efficiency of plasma antenna power into radiation can be no worse than that of a metal dipole antenna. It is also shown experimentally that the plasma in a dipole antenna can be self-consistently excited by an RF oscillator and that the excited RF oscillations can be efficiently radiated into the surrounding space. 相似文献
8.
K. F. Sergeichev V. Yu. Ionidi D. M. Karfidov N. A. Lukina 《Plasma Physics Reports》2013,39(13):1149-1157
It is shown that a “point” target in a conventional evacuated waveguide in the magnetic field of a mirror trap formed by two disk magnets axially magnetized in the direction perpendicular to the electric field vector represents a source of X-ray bremsstrahlung of electrons accelerated in an ECR discharge with a broad range of photon energies up to 0.8 MeV. The dosage rate of the source is ~1 R/h. The source fed from a conventional microwave oven has small dimensions and a low weight. It is easy-to-use and is suitable as a laboratory tool, in particular, in radiobiology and introscopy. After passing through the object, X-ray emission is recorded by a digital camera with the help of a highly sensitive X-ray fluorescent screen, which converts it into an optical image. 相似文献
9.
High-density (n > 1012 cm?3) argon-mercury plasma produced by a short (t ~ 20 μs) high-power pulsed discharge in argon with an admixture of mercury vapor at a discharge current of ~50 A, an argon pressure of ~4 mm Hg, and a mercury vapor pressure of ~10?3 mm Hg was studied using optical spectroscopy and radio physics methods. It is found that the lifetime of this plasma after the end of the discharge pulse is up to 10?2 s. It is shown that such an abnormally long lifetime of such an afterglow plasma, as compared to the plasma of an argon discharge without an admixture of mercury vapor, is related to the long residence time of atoms and ions of both argon and mercury in highly excited states due to chemi-ionization processes involving long-lived metastable argon ions. It is suggested that dissociative recombination of highly excited molecular ions of argon play an important role in the transfer of excitation to argon atoms and ions that are close to autoionization states. 相似文献
10.
Zakabunin AI Mishukova OV Khrapov EA Sergeichev DS Boiarskikh UA Sverdlov ED Filipenko ML 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》2007,(2):21-25
A sample of the human cDNA was used to amplify the segment encoding biosynthesis of chymotrypsin-like protease of kallikrein-7 and its cloning into the expressing plasmid pET23a(+).Biosynthesis of KLK-7 in transformed E. coil BL21(DE3) cells was accompanied by formation of insoluble inclusion bodies. The recombinant KLK-7 was extracted from the inclusion bodies using 7 M urea in the presence of 2-mercaptoethanol. The extracted recombinant KLK-7 was purified using methods of metal-chelate and ion-exchange chromatography, converted into a soluble form, and used for preparing monospecific antiserum. 相似文献