共查询到20条相似文献,搜索用时 375 毫秒
1.
Y Choyal Lalit Gupta Preeti Vyas Prasad Deshpande Anamika Chaturvedi K C Mittal K P Maheshwari 《Sadhana》2005,30(6):757-764
We have indigenously developed a twenty-stage vertical structure type Marx generator. At a matched load of 90–100 Ω, for 25
kV DC charging, an output voltage pulse of 230 kV, and duration 150 ns is obtained. This voltage pulse is applied to a relativistic
electron beam (REB) planar diode. For a cathodeanode gap of 7.5 mm, an REB having beam voltage 160kV and duration 150ns is
obtained. Brass as well as aluminum explosive electron emission-type cathodes have been used 相似文献
2.
The energy spectra of runaway electrons generated in a gas diode under the action of voltage pulses with a front width of
∼300 ps and amplitude of ∼140 kV have been studied using a time-of-flight spectrometer at nitrogen pressures in a range of
0.1–760 Torr. The delay of runaway electron beam pulse relative to the driving voltage pulse has been determined. The electron
energy depends in a complicated manner on the nitrogen pressure in the gas diode and on the cathode geometry. A minimum breakdown
voltage for a gap between tubular cathode and flat anode has been observed at a nitrogen pressure of ∼100 Torr. A decrease
in the nitrogen pressure below 100 Torr leads to an increase in the maximum of voltage drop on the gap and the energy of the
main fraction of electrons. 相似文献
3.
A. M. Bechasnov V. L. Bratman N. G. Kolganov S. V. Mishakin S. V. Samsonov 《Technical Physics Letters》2010,36(2):140-143
A relativistic backward wave oscillator for the 10-GHz range with the oscillation frequency tuned within about 5% by changing
the accelerating voltage from 600 to 350 kV has been developed. Discrete variations in the voltage and the corresponding frequency
tuning from pulse to pulse is rapidly performed by changing the anode-cathode distance in the vacuum diode without breaking
vacuum in the working volume. During this, the electron beam power remains almost constant, while the output microwave power
varies within 0.4–0.8 GW. The introduction of a dielectric cylinder into the accelerating gap provides a smooth voltage drop
from 600 to 350 kV with the corresponding frequency tuning during a 20-ns pulse. 相似文献
4.
S. Ya. Belomyttsev I. V. Romanchenko V. V. Ryzhov V. A. Shklyaev 《Technical Physics Letters》2008,34(5):367-369
A model of the initial stage of gas discharge has been developed within the framework of the particle in cell (PIC) method,
with allowance for the space charge and particle collisions described using the Monte Carlo (MC) numerical simulation technique.
The PIC/MC simulations of the initial stage of discharge under conditions of the electric field strength to gas pressure ratio
E/P > 1 kV/(cm Torr) showed that a beam of runaway electrons is formed within ∼10 ps near the cathode, which consists of both
emitted electrons and those generated as a result of the gas ionization. The duration of the beam pulse is determined primarily
by plasma screening of the external electric field near the cathode and amounts to 10–20 ps. 相似文献
5.
N. I. Aizatskii E. Z. Biller V. A. Kushnir V. V. Mitrochenko I. V. Khodak V. F. Zhiglo 《Technical Physics Letters》1998,24(10):762-763
The possibility of using metal-insulator cathodes in rf guns of 10 cm linear resonant electron accelerators has been studied
experimentally for the first time. Results of calculations and the development of a prototype cathode are described. Results
of an experimental investigation of the operating regimes of an rf gun are presented. The gun delivered a beam having a particle
energy greater than 300 keV, a pulse length of 40–50 ns, and a pulsed current of 3.5–4.5 A.
Pis’ma Zh. Tekh. Fiz. 24, 36–39 (October 12, 1998) 相似文献
6.
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
7.
A periodic linear measure is described for use in scanning electron microscopes, which has eight values for line width in
the micrometer and submicrometer ranges. Methods have been developed for calibrating the SEM with such a measure, which are
not sensitive to errors in beam focusing.
Translated from Izmeritel'naya Tekhnika, No. 4, pp. 48–52, April, 2000. 相似文献
8.
Mingsen Guo K. H. Lam D. M. Lin S. Wang K. W. Kwok Helen L. W. Chan X. Z. Zhao 《Journal of Materials Science》2008,43(2):709-714
Lead-free K0.5Na0.5NbO3–K5.4Cu1.3Ta10O29–MnO2 (KNN–KCT–Mn) ceramics have been prepared by a conventional ceramic sintering technique. The ceramics show excellent piezoelectric
properties for application in power devices, and the optimum properties measured are as follows: piezoelectric constant d
33 = 90 pC/N, planar electromechanical coupling factor k
p = 0.40, mechanical quality factor Q
m = 1900, remanent polarization P
r = 11.8 μC/cm2, coercive field E
c = 0.85 kV/mm. A Rosen-type piezoelectric transformer with a dimension of 21 mm × 6 mm × 1.2 mm was fabricated using the KNN–KCT–Mn
ceramics. Properties of the piezoelectric transformer operating in the first and second modes have been characterized. For
the first mode, the transformer has a maximum output power of 0.7 W with a temperature rise of 14 °C. For the second mode,
the maximum output power of the transformer is 1.8 W with a temperature rise of 33 °C. KNN–KCT–Mn ceramics have shown to be
a potential lead-free candidate to be used in high-voltage–low-current devices. 相似文献
9.
A new precision circuit has been developed for a phase-type transformer displacement converter in which the errors of the
phase shifter are balanced out; the working principle is described.
__________
Translated from Izmeritel’naya Tekhnika, No. 10, pp. 26–27, October, 2007. 相似文献
10.
Indirect determination of X-ray generator kilovoltage (kV) using the ratio of differentially filtered beam measurements has been known for 20 years. Measurement of generator potentials used for diagnostic computed tomography (CT), conventional X-ray, and mammography typically requires filter cassettes or special instruments in the X-ray beam; the resulting readings are usually accurate within ±2%. A related technique, free of many theoretical and practical restrictions, provides simplified generator potential measurements with significantly improved accuracy. Curve fitting provides a simple relationship predicting generator kV from a measured filter response ratio. Routine use has established that this technique is robust, reliable, repeatable, and more accurate than most working standards 相似文献
11.
Quan Jin Mingtao Zheng Yongjian Wu Chunlin Xie Yong Xiao Yingliang Liu 《Journal of Materials Science》2012,47(2):711-719
A facile approach was developed for synthesis of carbon hollow microspheres (CHM) via carbonization of the hollow polymer
microspheres prepared from polymerization in the presence of l-lysine acted as in situ template. The physical and chemical structures of the samples were investigated by X-ray powder diffraction,
Raman spectrum, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SEM and TEM images show that
the products consist of a large scale of monodisperse CHM with a size of about 1.1–1.3 μm. Furthermore, the resulting CHMs
possess a surface area of 559 m2 g−1 and a pore volume of 0.27 cm3 g−1. The morphology and the size of the as-obtained samples can be controlled by the polymerization temperature, polymerization
time, and the dosage of l-lysine. Moreover, a possible formation mechanism of the CHM has been put forward according to the experimental data available. 相似文献
12.
P. A. Bokhan P. P. Gugin Dm. E. Zakrevsky V. I. Solomonov A. V. Spirina 《Technical Physics Letters》2011,37(9):820-823
A CdS crystal has been excited by radially converging pulsed electron beam with an electron energy of up to E ≈ 18 keV, a beam current density at the target of up to 4 kA/cm2, and a pulse full width at half maximum within τ ≈ 12–100 ns. For comparison, the same crystal was pumped by electrons with
E = 170 keV at τ = 2.2 ns. A specific distinctive feature of the excitation by powerful low- and high-voltage electron beams
is the appearance of previously unreported long-wavelength generation with a peak at λ ≈ 535 nm in the electron-hole plasma
band. In the region of the interband transition with a peak at λ ≈ 515 nm, the generation spectra are similar to those known
from the literature. 相似文献
13.
Ferroelectric polymer films have been made by dispersingtgs powder. The dielectric constant ε′ of the films has been measured. The thermal behaviour of ε′ is also reported. Data have
been obtained from samples prepared with different weight concentrations (10–75%) oftgs. 相似文献
14.
A method is described for oscillographic recording of single-shot nanosecond processes on the basic of electron-optical converters,
and parameter measurements are reported for shockwaves in pulsed loading of materials by a high-current electron beam.
Translated from Izmeritel'naya Tekhnika, No. 10, pp. 43–44, October, 1996. 相似文献
15.
V. B. Avramenko 《Journal of Engineering Physics and Thermophysics》2007,80(3):599-603
The results of a radiation-spectroscopic investigation of the plasma generated by an ablation (erosion) pulse plasma generator
of cylindrical geometry operating at low pressure have been presented. The electron temperature for different dielectrics
has been determined from integral spectra with radial conversion of intensities and without it.
__________
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 3, pp. 164–168, May–June, 2007. 相似文献
16.
É. N. Abdullin A. M. Efremov B. M. Koval’chuk V. M. Orlovskii A. N. Panchenko É. A. Sosnin V. F. Tarasenko A. V. Fedenev 《Technical Physics Letters》1997,23(3):193-195
The development of a high-power HF laser pumped by a chemical nonchain reaction initiated by a radially converging electron
beam is reported. A radiation energy of ∼ 115 J with an efficiency of ∼ 8% in terms of deposited energy has been achieved
in a mixture with an active volume of ∼ 30 liters. It is shown that because of the high SF6 density, the total pressure jump in SF6–H2(D2) mixtures caused by the electron beam injection and the chemical reactions is several times smaller than that in the active
mixtures of exciplex lasers for the same input energies. This factor considerably facilitates the development of wide-aperture
HF and DF lasers with an SF6 fluorine donor pumped by an electron-beam-initiated chemical nonchain reaction.
Pis’ma Zh. Tekh. Fiz. 23, 58–64 (March 12, 997) 相似文献
17.
E. A. Bazyl’ A. D. Pogrebnyak B. P. Gritsenko S. V. Sokolov V. V. Staiko N. V. Sviridenko S. N. Bratushka 《Technical Physics Letters》1999,25(8):621-623
Atomic physics methods, atomic force microscopy, and testing of microhardness, wear resistance, and friction coefficient were
used to investigate Ti41-V41-Al18 samples implanted with iron (60 kV) and zirconium (40 kV) ions, and then exposed to a high-current electron beam with energy
fluxes of 2.7 and 5.5 J/cm2. The maximum concentration of iron ions is 16.5 at.% at a depth of 85 nm and that of zirconium ions 0.85 at.% at 56 nm. After
double implantation, the friction coefficient decreases and the wear resistance increases. After implantation and high-current
electron beam treatment, the depth of the hardened layer and the wear resistance increase.
Pis’ma Zh. Tekh. Fiz. 25, 66–73 (August 12, 1999) 相似文献
18.
Tarasenko V. F. Baksht E. Kh. Burachenko A. G. Lomaev M. I. Sorokin D. A. Shut’ko Yu. V. 《Technical Physics Letters》2010,36(4):375-378
Runaway electron beam parameters and current-voltage characteristics of discharge in helium, hydrogen, and nitrogen at pressures
in the range of several Torr to several hundred Torr have been studied. It is found that the maximum amplitudes of supershort
avalanche electron beams (SAEBs) with a pulse full width at half maximum (FWHM) of ∼100 ps are achieved in helium, hydrogen,
and nitrogen at a pressure of ∼60, ∼30, and ∼10 Torr, respectively. It is shown that, as the gas pressure is increased in
the indicated range, the breakdown voltage of the gas-filled gap decreases, which leads to a decrease in the SAEB current
amplitude. At pressures of helium within 20–60 Torr, hydrogen within 10–30 Torr, and nitrogen within 3–10 Torr, the regime
of the runaway electron beam generation changes and, by varying the pressure in the gas-filled diode in the indicated intervals,
it is possible to smoothly control the current pulse duration (FWHM) from ∼100 to ∼500 ps, while the beam current amplitude
increases by a factor of 1.5–3. 相似文献
19.
In this paper, the design and constructional details of a short-pulse electron beam generator are presented highlighting some
of the novel features of its operation. The diagnostic results of the electron beam, both in the diode and in the drift region,
are described. A 60-ns duration 200 keV, 30 kA electron beam has been obtained. 相似文献
20.
B. A. Knyazev J. B. Greenly D. A. Hammer E. G. Krastelev M. E. Cuneo 《Technical Physics Letters》1997,23(5):401-402
A new type of optical system for measurements of laser beam deflection has been developed and implemented experimentally.
The refractive index gradient in the anode plasma of a megavolt magnetically insulated diode in a high-power ion accelerator
has been measured with submicron resolution. The refractive index distribution in the layer was measured during the pulse
and the average electron density in the layer was determined.
Pis’ma Zh. Tekh. Fiz. 23, 63–68 (May 26, 1997) 相似文献