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1.
The feasibility of shock initiation in thin pentaerythritol tetranitrate (PETN) single crystals under the action of a pulsed high-current electron beam (0.25 MeV, 20 ns, 15 J/cm2) is shown experimentally. The real-time dynamic characteristics of crystal glow arising under the action of the electron beam and glow due to subsequent shock-wave-induced transformations are presented. A shock wave results from beam energy absorption and initiation of an exothermal chemical reaction in the irradiated layer. 相似文献
2.
B. A. Demidov V. P. Efremov Yu. G. Kalinin V. A. Petrov S. I. Tkachenko K. V. Chukbar 《Technical Physics》2012,57(3):405-409
The time ranges of the fracture of polymethylmethacrylate and polystyrene during the action of a shock wave generated by a
high-current pulsed electron beam are experimentally determined using laser probing in combination with electron-optical chronography.
It is shown that fractures occur during unloading of a material, i.e., after the passage of the shock wave. Although the characters
of fracture of these polymers near the surface irradiated by electron beam are different, the fracture wave velocities in
them are found to be close. 相似文献
3.
G. A. Ivanov A. V. Khaneft 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(6):765-771
A radiation-thermal mechanism of initiation of a PETN sample by a nanosecond-duration electron beam is examined. It is assumed that the energy of the electron beam is spent not only on heating the sample, but also on generating active species. The initiation of PETN was simulated using three-step kinetic mechanism. Calculations have shown that taking into account the formation of active species in the mechanism of PETN initiation significantly lowers the initiation energy threshold. 相似文献
4.
The results of an experimental investigation of acoustic vibrations (their frequency, amplitude, and attenuation coefficient) generated in a gas mixture as a result of the injection of a high-current pulsed electron beam into a closed reactor are presented. It is shown that the change in the phase composition of the initial mixture under the action of the electron beam leads to a change in the frequency of the sound waves and to an increase in the attenuation coefficient. By measuring the change in frequency, it is possible to evaluate with sufficient accuracy (about 2%) the degree of conversion of the initial products in the plasmochemical process. Relations describing the dependence of the sound energy attenuation coefficient on the size of the reactor and on the thermal and physical properties of the gases under study are derived. It is shown that a simple experimental setup measuring the parameters of acoustic waves can be used for monitoring the plasmochemical processes initiated by a pulsed excitation of a gas mixture. 相似文献
5.
The mechanisms behind limitation of current of nonrelativistic high-current electron beams in the plasma-filled diode immersed
in the external guiding magnetic field whose intensity is comparable with that of the beam self magnetic field are studied.
It is shown that the beam current is limited by transmission capacity of the double layer between the cathode and anode plasma
on the one hand and, on the other hand, by charge neutralization of the beam and by the decrease of the longitudinal velocity
of the beam electrons under the action of the induced electric field and of the beam self magnetic field. The effect of the
beam self fields on its cross-sectional current density and energy distributions is studied. Results of the numerical simulations
are in good agreement with the experimental data. 相似文献
6.
E. F. Dudarev A. B. Markov A. N. Tabachenko G. P. Bakach S. D. Polevin V. P. Rotshtein N. V. Girsova 《Russian Physics Journal》2007,50(12):1205-1211
The results of investigations of fracture behavior in coarse-grained and ultrafine-grained aluminum under the action of a
nanosecond relativistic high-current electron beam in a SINUS-7 accelerator and under conditions of quasi-static tensile loading
are reported. It is shown that for both types of deformation, irrespective of the grain size, the fracture is ductile both
in deformation and structural features. Based on the examination of the fracture surface, it is found out that under quasi-static
loading decohesion of coarse-grained and ultrafine-grained aluminum occurs through shear, and under spalling condition by
rupture. It is shown for both grain structures that the thickness of the separated layer increases with the irradiated specimen
thickness.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 32–38, December, 2007. 相似文献
7.
An analyzer is created for time-resolved measurements of the electron pitch-angles in high-current microsecond relativistic electron beams in a strong magnetic field. The electron pitch-angles in a 500-keV relativistic electron beam with a current density of ∼1 kA/cm2 and a 1-μs flat-top current profile are measured. The diode proposed previously by the authors allows one to produce a high-current electron beam in which pitchangles vary only slightly with time and over the beam cross section. 相似文献
8.
V. T. Uvarov A. G. Ponomarev Yu. F. Lonin V. V. Uvarov A. N. Nikitin V. N. Robuk T. I. Ivankina V. F. Klepikov V. V. Lytvynenko S. E. Donets M. I. Bazaleev 《Physics of Particles and Nuclei Letters》2014,11(3):274-281
The characteristic manifestations of radiation-acoustic effects in metals and alloys under the irradiation of a high-current relativistic electron beam, leading to a melt surface with the partial removal of material from the surface, are studied in this paper. An increase in the acoustic emission in the samples when they are irradiated with a high-current electron beam is experimentally observed. It is shown that the primary mechanism for the generation of radiation-acoustic pulses in irradiated refractory metals is a stress-relieving mechanism. The amplitudes of the acoustic pulses after the second and subsequent electron pulses do not change, which indicates a correlation between the amplitude of the acoustic signal and the surface structure of the irradiated material. 相似文献
9.
Meisner S. N. Meisner L. L. Neiman A. A. Panin S. V. Vlasov I. V. 《Russian Physics Journal》2021,64(5):850-858
Russian Physics Journal - It is shown that by irradiating nickel titanium surfaces with a low-energy high-current electron beam of a microsecond duration at the energy densities of Es = 1.5 and 3.7... 相似文献
10.
Mesyats G.A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):683-689
The processes occurring in the diodes of high-current electron accelerators which affect the electron beam structure are discussed. Two types of diodes are analyzed: planar diodes producing large cross-section beams, and magnetically insulated diodes producing cylindrical beams. The effects considered are: the screening effect, the effect of touches, the relay effect, the ring effect, etc. They are entirely associated with the explosive electron emission occurring on the cathode of a high-current diode. Methods which can be employed to eliminate or control some of these effects are described-namely, the application of an additional magnetic field, artificial initiation of emission centers, and employment of metal-dielectric cathodes. Examples of several types of cathode are given 相似文献
11.
Using metallography, x-ray diffraction analysis, diffraction electron microscopy, and microhardness measurements we have investigated
the results of the action of a pulsed low-energy, high-current electron beam on the phase composition, defect structure, and
mechanical properties of the hard alloy WC-30% steel 110G13. We have observed and studied in detail the regions of elevated
microhardness (the microhardness of the material in these regions is 1.5–2.0 times greater than the original value) located
on the irradiated surface and in the interior of the material. We have shown that the number of zones of elevated microhardness
increases with an increase in the number of pulses in the electron beam treatment. We consider the mechanisms for hardening
of the material by a low-energy, high-current electron beam. We conclude that the increase in the microhardness of the alloy
is due to dispersion of the carbide phase, precipitation of nanometric complex carbide particles, strain hardening, and hardening
due to polymorphic transformation (γ→∈) of the binder.
Tomsk State Architectural Design Academy; Institute of Physics of Strength and Materials Science, Siberian Branch, Russian
Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 104–110, August, 1996. 相似文献
12.
B. P. Aduev G. M. Belokurov S. S. Grechin A. V. Puzynin 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(3):449-451
The results of measurements of the velocity of shock waves generated in pressed pentaerythritol tetranitrate samples by a
pulsed electron beam (0.25 MeV, 15 J/cm2, and 20 ns) and of the velocity of expansion of the explosion products into vacuum are presented. It was demonstrated that,
during the interaction of the electron beam with pentaerythritol tetranitrate, it experiences decomposition accompanied by
a pressure rise high enough to produce a shock-wave initiation of the sample. 相似文献
13.
S. A. Atroshenko A. N. Zubareva V. A. Morozov G. G. Savenkov A. V. Utkin 《Physics of the Solid State》2018,60(2):238-243
Experimental studies of cerium at high rates and nanosecond durations of action have been performed. The isomorphic phase transition was studied upon shock compression. The spall strength of cerium has been determined. Cerium demonstrates anomalous compressibility upon dynamic loading. Stress waves dampen under action of a high-current electron beam due to the energy dissipation during fragmentation and twinning. 相似文献
14.
A. V. Agafonov 《Physics of Particles and Nuclei Letters》2006,3(1):S7-S11
The results of experimental investigation and numerical modeling of the generation of low-energy (tens of keV) high-current (up to tens of kA) electron beams in a low-impedance system consisting of a plasma-filled diode with a long plasma anode, an auxiliary hot cathode, and an explosive emission cathode. The low-current low-voltage beam from the auxiliary cathode in an external longitudinal magnetic field is used to produce a long plasma anode, which is simultaneously the channel of beam transportation by residual gas ionization. The high-current electron beam is formed from the explosive emission cathode placed in the preliminarily formed plasma. Numerical modeling is performed using the KARAT PIC code. 相似文献
15.
Current and space-charge density distribution calculation is of great significance for numerical analysis and design of high-current electron guns and beams. When the electrons’ thermal initial velocities are taken into account, though there have been some numerical methods published, the calculation is very complicated. By introducing equivalent meridional potential and projection trajectory theory, the curvilinear axis trajectory equation for electrons neighboring to a central curved trajectory in rotationally symmetric electro-magnetic fields is derived in first- and second-order approximations. The evolution equation of the current density distribution of toroidal electron sub-beams is derived and it can be used to calculate the current and charge density distribution in electron beams and guns in iteration calculation. A compact numerical algorithm for calculating round high-current electron guns and beams was developed and related program was written as well. As examples, the evolution of the current density distribution of a Pierce gun and a periodic magnetic focusing high-current electron beam is simulated. This proves that this method is effective and practical. 相似文献
16.
We analyze the properties of a high-current electron beam formed in an electron source based on a plasma-filled diode and a linear pulsed transformer. The beam parameters are determined by measuring bremsstrahlung X-rays and the beam current, as well as the photographs of the diode gap in the optical range, of the anode in X-rays, and beam autographs. A beam with a current of ~100 kA and a mean electron energy exceeding 0.7 MeV for an accelerating voltage amplitude of ~1 MV is obtained. The diameter of the generated beam is ~1 cm. The electron beam from the plasma-filled diode makes it possible to attain a high anode power density (>1010 W/cm2) for exciting shock waves, for obtaining high pressures, and for generating powerful X-rays. 相似文献
17.
G. G. Savenkov V. A. Morozov I. A. Os’kin V. A. Bragin A. A. Lukin 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(5):769-773
Experimental results on the ignition of energetic two- and three-layer potassium picrate- and lead(II, IV) oxide-based compositions with a high-current electron beam of nanosecond duration are reported. It is shown that the sustainability of explosive transformations in layered compositions depends on the boundary conditions and the additional impact of the cathode flame (high-temperature metal plasma). 相似文献
18.
Loza O.T. Strelkov P.S. Ivanov I.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(3):336-339
Experiments with a Cherenkov plasma maser (CPM) driven by a high-current relativistic electron beam of microsecond pulse duration are described. The results obtained show that the principle of operation of the CPM makes it possible to avoid the problem of microwave pulse shortening, which is inherent to vacuum devices of relativistic high-current microwave electronics. A 800-ns microwave pulse with an energy of 21 J was obtained at a peak power level of 40 MW (the efficiency being 4%) in a broad (~100%) frequency band 相似文献
19.
A. V. Gul’kin D. V. Postnikov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(2):277-281
Radiation damage of a beryllium surface by a high-current electron beam at the GSEP-3 accelerator is considered. The degree of damage of beryllium samples has been determined. The temperature fields inside the sample and the distributions of thermal stresses have been calculated. The reasons for beryllium surface cracking formation have been found. The concentrations of point defects have been calculated. The possible reasons for an increase in microhardness of the irradiated beryllium surface layer are discussed. 相似文献
20.
Evolution of vacancy defects in the surface layers of a metal irradiated with a pulsed electron beam
The distribution of vacancy defects in the surface layers of α-Fe after irradiation with a high-current pulsed electron beam is studied experimentally by unique nuclear-physical methods
— low-energy positron annihilation, Rutherford backscattering (RBS), and proton-induced x-ray emission (PIXE). Regions with
low local density, which are sources of crater formation on the surface of the irradiated sample, are observed by scanning
a proton microbeam. Positron lifetime measurements reveal that as the electron beam power increases, nonequilibrium vacancies
tend to be captured by carbon impurity atoms.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 618–622 (25 April 1997) 相似文献