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1.
The electrical and luminescent characteristics of a barrier-discharge lamp filled with a Kr/CCl4 (150: 1) mixture are experimentally studied versus the value of pd, which varies in the range (7.6–14) × 103 Pa cm. When simulating the gas discharge using similarity parameters, the following relationships are fulfilled: for pd = const (p is the pressure, d is the interelectrode distance), the pulse duration and the mean current density are τ
j
∼ 1/p and 〈j〉 ∼ p; the surface charge density on the electrodes, σ ∼ const; the duration of the UV radiation pulse and the efficiency of UV
radiation due to a KrCl* (222 nm) exciplex, τrad ∼ 1/p and η ∼ p
2. The maximal radiation efficiency achieved in the experiments is about 13%. Deviations from the similarity laws for the gas
discharge are related to the filamentary form of the observed discharge. Qualitative analysis indicates that similarity laws
may be fulfilled for such a form of discharge as well but locally, within a single filament. 相似文献
2.
V. F. Tarasenko E. Kh. Baksht A. G. Burachenko M. I. Lomaev D. A. Sorokin Yu. V. Shut’ko 《Technical Physics》2010,55(6):904-907
Switchover from a runaway-electromnduced volume discharge to a spark is studied when a nanosecond discharge is initiated in
high-pressure nitrogen an d air at a voltage of 50–250 kV. In the case of a cathode with a small radius of curvature and a
flat anode and in the presence of cathode spots, the leader of the spark channel may propagate from the flat cathode. When
the rate of rise of the voltage across centimeterwide gaps is high (dU/dt ∼ 1015 V/s or higher), cathode spots in the case of a corona discharge emerge within 200 ps. 相似文献
3.
The temporal behavior of VUV spectra of capillary discharge with a rate of a current rise on the order of 1012 A/s is studied. The current is generated using an inductive storage unit with a plasma-erosion opening switch. This discharge
is accompanied by the generation of a shock wave on an inner wall of a capillary and by its subsequent cumulation on the discharge
axis. The capillary is prefilled with argon at a pressure of 80 Pa. Radiation spectra are obtained using an off-Rowland spectrograph
based on a concave grating with optimal focusing in the wavelength range of 20 nm. The radiation is recorded with a detector
based on a microchannel plate with a time resolution of 20 ns, which makes it possible to separate the spectra of two phases
of the discharge, i.e., the cumulation phase of the shock wave in argon that fills the capillary (T
e
∼ 20–30 eV) and the phase of subsequent discharge in a substance desorbed from the capillary wall T
e
∼ 50 eV). 相似文献
4.
A. N. Bastrikov A. A. Zherlitsyn A. A. Kim B. M. Kovalchuk S. V. Loginov V. P. Yakovlev 《Russian Physics Journal》1999,42(12):1011-1015
Experiments have been performed on the GIT-4 generator with a plasma opening switch to study the operation of a circuit connecting
the load and the switch through an untriggered spark gap depending for its operation on a discharge over the surface of a
dielectric in vacuum. The current switching into inductive loads of different inductance was investigated. The dependence
of the time the switch is open on load inductance has been found. It has been demonstrated that the surface-discharge spark
gap can be used at current rise rates of up to ∼2·1013 A/s.
Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh
Uchebnykh Zavedenii, Fizika, No. 12, pp. 31–35, December, 1999. 相似文献
5.
Photogalvanic effect in an asymmetric system of three quantum wells in a strong magnetic field 总被引:2,自引:0,他引:2
The photogalvanic effect (PGE) in an asymmetric undoped system of three GaAs/AlGaAs quantum wells illuminated with white light
of various intensities is investigated in magnetic fields up to 75 kOe at temperatures ranging from 4.2 K up to 300 K. A maximum
of the spontaneous photogalvanic current J
PGE as a function of the magnetic field predicted by A. A. Gorbatsevich et al., JETP Lett. 57, 580 (1993), is observed. Analysis of the experimental data shows that the main initial characteristic of the PGE is not
the spontaneous current but rather the electromotive force E
PGE arising in the direction perpendicular to the applied magnetic field. It is determined that this emf is independent of the
intensity of the incident light, increases linearly with the size d of the illuminated region, and decreases slowly with temperature: E
max
PGE
∼0.8 V at 300 K and ∼0.1 V at 4.2 K for d∼3 mm. The curve E
PGE(H) at room temperature is determined with allowance for the strong transverse magnetoresistance of the nanostructure.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 3, 197–202 (10 February 1996) 相似文献
6.
The results of experimental investigations and an analysis of the temperature dependences of the thermally stimulated depolarization
current are presented for zinc-oxide ceramics suitable for use in high-voltage varistors. A model for the depolarization phenomena
is proposed that takes into account charge exchange on localized electronic states on both sides of the intercrystallite potential
barrier. The model is used to obtain estimates of the ionization energy and density of shallow (∼0.07 eV, 1×1017 cm−3) and deeper (∼0.2 eV, 1×1018 cm−3) bulk levels and surface-localized levels (∼0.1 eV, 1×1013 cm−2).
Zh. Tekh. Fiz. 67, 60–63 (October 1997) 相似文献
7.
A. T. Pugachev N. P. Churakova N. I. Gorbenko Kh. Saadli E. S. Syrkin 《Journal of Experimental and Theoretical Physics》1998,87(5):1014-1018
The thermal expansion coefficient a and structure of C60 films with thickness t∼3–10 nm were investigated in the temperature interval from room to liquid-nitrogen temperature by electron-optical methods.
The thermal expansion coefficient was determined from the temperature shift of the diffraction maxima in the electron diffraction
patterns. The objects of investigation were epitaxial C60 films condensed in vacuum on a (100) NaCl cleavage surface and oriented in the (111) plane. A surface-induced size effect
in the thermal expansion coefficient was observed. It was established that as t decreases α
f increases and is described well by the relation α
f=17·10−6 K−1+8.3·10−5 nm K−1
t
−1. This relation was used to estimate the linear expansion coefficient α
s of the C60 surface in the (111) plane as α
s=60·10−6K−1, which is several times larger than the bulk value. The experimental results agree satisfactorily with the theoretical calculations
of the mean-square displacements of molecules located in a region near the surface.
Zh. éksp. Teor. Fiz. 114, 1868–1875 (November 1998) 相似文献
8.
A study is made of the effect of pulse repetition rate (0.1−103 s−1) and average discharge current (0–1 A) on the breakdown delay time and burning voltage of low-pressure glow discharges (p<0.1 Pa) in an electrode system of the reverse magnetron type with a large cathode surface area (≈103 cm2). It is shown that increasing the repetition rate leads to a many-fold reduction in the statistical spread in the delay time
and in the discharge formation time, while the average discharge current has a significant effect on the burning voltage.
The mechanism for the observed phenomena is interpreted qualitatively in terms of the presence of thin dielectric films on
the cathode surface.
Zh. Tekh. Fiz. 69, 20–24 (May 1999) 相似文献
9.
A new phenomenon — intense luminescence of noncolored lithium fluoride (LiF) crystals excited by an electrodeless pulsed microwave
discharge at the prebreakdown stage of development — is observed. This luminescence consists of the luminescence of short-lived
aggregate F2 and F
3
+
color centers at room temperature. It is shown that the density of short-lived color centers induced in the surface layer
of LiF crystals by a microsecond microwave discharge reaches values of ∼1019−1020 cm−3.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 3, 163–167 (10 August 1997) 相似文献
10.
N. P. Kulish P. A. Maksimyuk N. A. Mel’nikova A. P. Onanko A. M. Strutinskii 《Physics of the Solid State》1998,40(7):1145-1146
An investigation was made of the influence of γ irradiation on the temperature dependences of internal friction in disk-shaped silicon substrates in the kilohertz frequency
range. After exposure to doses of 104 and 105 R, two dominant internal friction peaks were observed at ∼330 and ∼450 K with activation energies H
1=0.6 eV and H
2=0.9 eV, respectively. These peaks were evidently caused by reorientation of interstitial silicon atoms in dumbbell configurations.
Fiz. Tverd. Tela (St. Petersburg) 40, 1257–1258 (July 1998) 相似文献
11.
B. P. Barkov O. N. Baloshin N. V. Batalova V. V. Vladimirskii V. K. Grigor’ev O. N. Erofeeva Yu. V. Katinov I. Ya. Korol’kov V. I. Lisin V. N. Luzin V. N. Nozdrachev V. V. Sokolovskii G. D. Tikhomirov S. A. Uzunyan Yu. P. Shkurenko 《JETP Letters》1998,68(10):764-769
The preliminary results of an investigation of a system of two K
S
mesons in the mass interval 1600–1950 MeV are reported. The events were obtained on a 6-m magnetic spark spectrometer at ITEP
in π −
p interactions at 40 GeV, using a neutral trigger which suppressed both charged particles and γ rays. A peak of width ≃30 MeV
with statistical significance not lower than six standard deviations is observed with momentum transfer selection |tu|0.23
GeV2 near the mass 1775 MeV of the K
S
K
S
system. The observed phenomena can be interpreted as the existence of one resonance with the indicated parameters, or two
narrower resonances. In the latter case, their masses are 1768±1.5 and 1787±1.5 MeV. The widths of these states are comparable
to the mass resolution of the spectrometer (∼5 MeV). Estimates of the product σ ⋅BR(K
S
K
S
) give ∼1.5 and 2.5 nb, respectively, for the first and second states.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 727–731 (25 November 1998) 相似文献
12.
Md. Salimullah R. R. Sharma V. K. Tripathi 《Applied Physics A: Materials Science & Processing》1981,25(3):361-365
Using the fluid model for the nonlinear response of ions, we have studied the nonlinear scattering of an electromagnetic ion
cyclotron wave off the ion acoustic wave in a plasma. The low frequency nonlinearity arises through the parallel ponderomotive
force on ions and the high frequency nonlinearity arises through the nonlinear current density of ions. For a typical nonisothermal
plasma (T
e/T
i∼10) the threshold for this instability in a uniform plasma is ∼1mW/cm2. At power densities ≳102 W/cm2, the growth rate for backscatter turns out to be ∼104s−1. 相似文献
13.
Peter Wardman Mark J. Burkitt Kantilal B. Patel Andrew Lawrence Clare M. Jones Steven A. Everett Borivoj Vojnovic 《Journal of fluorescence》2002,12(1):65-68
Lucigenin (LC2+, bis-N-methylacridinium) and 2,7-dichlorofluorescin (DCFH2) are widely used as chemiluminescent or fluorescent probes for cellular oxidative stress, to reflect levels of superoxide (O2
·–) and hydrogen peroxide, respectively. We report mechanistic studies that add to the growing evidence for the unsuitability of either probe except in very well-defined circumstances. The ability for lucigenin to generate superoxide via reduction of LC2+ to LC·+ and redox cycling with oxygen depends on the reduction potential of the LC2+/LC·+ couple. Redox equilibrium between LC·+ and the redox indicator benzyl viologen is established in microseconds after generation of the radicals by pulse radiolysis and indicated E(LC2+/LC·+) –0.28 V vs. NHE. Reaction of LC·+ with O2 to generate O2
·– was also observed directly similarly, occurring in milliseconds, with a rate constant k 3 × 106
M
–1 s–1. Quinones act as redox mediators in LC·+/O2 redox cycling. Oxidation of DCFH2 to fluorescent DCF is not achieved by O2
·– or H2O2, but NO2
·) reacts rapidly: k 1 × 107
M
–1 s–1. Oxidation by H2O2 requires a catalyst: cytochrome c (released into the cytosol in apoptosis) is very effective (even 10 nM). Fluorescence reflects catalyst level as much as O2
·–) production. 相似文献
14.
V. A. Andronov S. A. Bel’kov A. V. Bessarab I. N. Voronich S. G. Garanin A. A. Gorbunov V. N. Derkach G. V. Dolgoleva A. I. Zaretskii V. M. Izgorodin B. N. Ilyushechkin G. A. Kirillov G. G. Kochemasov Yu. V. Kuratov V. I. Lazarchuk V. A. Lebedev V. M. Murugov L. S. Mkhitar’yan A. V. Okutin S. I. Petrov A. V. Pinegin N. N. Rukavishnikov A. N. Razin A. V. Ryadov A. V. Senik N. A. Suslov S. A. Sukharev V. A. Tokarev 《Journal of Experimental and Theoretical Physics》1997,84(3):485-488
The results of the first experiments devised to investigate the mixing of thin layers of Al and Au during the laser acceleration
of flat three-layer targets of Si (5 μm), Al (2 μm), and Au (0.05–0.26 μm) by radiation converted to the second harmonic from the Iskra-4 iodine laser with an intensity of 4×1013−7×1013 W/cm2 (τ
0.5∼1 ns), which acts on the Si side of the target. A method for detecting the occurrence of mixing is developed. It is established
that under the experimental conditions the thickness of the mixing region is at least ∼0.15 μm. The results of a theoretical analysis of the evolution of the disturbances leading to mixing are presented.
Zh. éksp. Teor. Fiz. 111, 882–888 (March 1997)
Deceased. 相似文献
15.
A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge
is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 × 10−5 Torr. The RF power, up to 10 kW (of which ∼50% is reflected back), with a typical pulse length of 50 ms, is injected into
the vacuum chamber of the ADITYA tokamak by a LHCD grill antenna and is used for plasma formation. The average coupled RF
power density (the RF power/a typical volume of the plasma) is estimated to be ∼5 kW/m3. When the ECR appears inside the tokamak chamber for the given pumping frequency (f = 3.7 GHz) a plasma with a density (n
e) ∼ 4 × 1016 m−3 and electron temperature ∼8 eV is produced. The density and temperature during the RF pulse are measured by sets of Langmuir
probes, located toroidally, on either side of the antenna. Hα signals are also monitored to detect ionization. An estimate of density and temperature based on simple theoretical calculation
agrees well with our experimental measurements. The plasma produced by the above mechanism is further used to characterize
the ECR-assisted low voltage Ohmic start-up discharges. During this part of the experiments, Ohmic plasma is formed using
capacitor banks. The plasma loop voltage is gradually decreased, till the discharge ceases to form. The same is repeated in
the presence of ECR-formed plasma (RF pre-ionization), formed 10 ms prior to the loop voltage. We have observed that (with
LHCD-induced) ECR-assisted Ohmic start-up discharges is reliably and repeatedly obtained with reduced loop voltage requirement
and breakdown time decreases substantially. The current ramp-up rates also decrease with reduced loop voltage operation. These
studies established that ECR plasma formed with LHCD system exhibits similar characteristics as reported earlier by dedicated
ECR systems. This experiment also addresses the issue of whether ECR plasma formed with grill antenna exhibits similar behavior
as that formed by single waveguide ECR antenna. Our experimental observations suggest that the characteristics of (LHCD system-induced)
ECR-assisted Ohmic start-up discharges show similar properties, reported earlier with normal ECR-assisted Ohmic start-up discharges
and hence LHCD system may be used as ECR system at reduced toroidal magnetic field for other applications like wall conditioning.
相似文献
16.
The generation of 1/f noise is demonstrated experimentally in a system consisting of a superconducting film carrying a transport current in contact
with a boiling liquid coolant. It is found that wide-band 1/f noise with a large amplitude of the fluctuations is observed over a wide range of parameters. This noise is attributed to
the fact that the sub-systems in contact have the same character of the relaxational dependences δT(t)∼ t
−1/2.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 9, 739–742 (10 May 1996) 相似文献
17.
Studies of a classical III–V semiconductor (InSb) doped with 3d magnetic ions (Mn2+, having a localized spin S=55/2) reveal some unexpected transport properties. It is found that the transition from the metallic to the low-temperature
insulator phase occurs at an impurity concentration N
Mn∼N
cr=2× 1017 cm−3 and a temperature T<T
cr∼1 K. Under these conditions a giant negative magnetoresistance arises. The experimental results can be explained in terms
of the onset of a hard Mott-Hubbard gap Δ in the impurity band formed by the shallow manganese acceptor in InSb at N
Mn∼N
cr. A model describing the gap formation is proposed.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 5, 358–362 (10 March 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
18.
R. P. Babertsyan É. S. Badalyan G. A. Egiazaryan É. I. Ter-Gevorkyan 《Technical Physics》1998,43(9):1035-1038
A steady-state Penning ion source is studied experimentally. Depending on the geometric parameter l
a
(the anode length to diameter ratio) and pressure, maxima are observed in the discharge current and in the ion beam current
extracted from an aperture at the center of the cathode. It is shown that at pressures of the order of 10−4 Torr, two maxima appear in these currents: one, for short discharge gaps with l
a
=1–1.5, corresponds to a diverging ion beam, and the other, for longer anodes with l
a
=4–5, to a collimated ion beam. At pressures of the order of 10−5 Torr, only one maximum appears in these currents, for short anodes l
a
=2–3 with a diverging ion beam. A physical explanation is proposed for these findings.
Zh. Tekh. Fiz. 68, 29–32 (September 1998) 相似文献
19.
Measurements have been made of the Hall coefficientR of some alloys of silver in palladium over the temperature range 1°K to 120°K. The alloys contain between ∼1 and ∼10 at.-%
silver. Values ofR were also obtained at room temperature and these were in good agreement with earlier published work. The values ofR are negative in all the alloys, and |R| increases both on reducing the temperature and increasing the silver concentration,c. Below ∼10°K, |R| becomes independent of temperature but shows a linear dependence onc, increasing by a factor of 2.5 over the concentration range measured.
This increase is too great to be accounted for in terms of band structure changes alone, so we have examined the effects of
anisotropic impurity scattering. To a first approximation it can be shown thatR is proportional to an anisotropy parameterA, defined asA=〈τ
2(k)〉/〈τ(k)〉2, whereτ(k) represents the relaxation time of an electron in a statek, and 〈〉 is an average over the Fermi surface. In palladium we assume that the majority of the current is carried by the s-electrons.
In the presence of silver impurities these electrons can be scattered into s-states or d-states with relaxation times given
byτ
ss
α1/c(1−c) andτ
sd
α1/c
2(1−c) respectively. FollowingPlate we have assumed thatτ
ss is isotropic and thatτ
sd is anisotropic, leading to an overall anisotropic relaxation time for impurity scattering. We then find the parameterA increases approximately linearly with silver content, in accordance with our experimental results. 相似文献
20.
G. A. Shneerson 《Technical Physics》2003,48(3):374-375
On the assumption that a spark discharge in water is quasi-steady, its pressure and channel radius are calculated. It is shown
that the key discharge parameter is the action integral S=∫
0
t
i
2
dt, where i is the current in the channel. The conductivity only slightly affects the computational results and thus can be assumed to
be constant. The formulas obtained can be applied to a discharge along the axis of a cylindrical water-filled chamber if the
deformation of its walls over the discharge time is negligibly small and the pulse duration is several times greater than
the time of sound propagation in water from the axis of the chamber to its wall. At relatively low pressures (P≤108 Pa), P∼R
−4/3, where R is the chamber radius. 相似文献