2011

Ryzhanskii V. A., Syrunin M. A. Explosion resistance of a steel cylindrical shell // Combustion, Explosion, and Shock Waves. 2011. Т. 47. № 1. С. 115 - 122.

Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

This paper gives an overview of experimental data on the behavior of steel cylindrical shells filled with water or air and repeatedly loaded by an explosion from inside, up to failure. Semi - empirical formulas are obtained which provide fairly easy and reliable estimates of the main parameters of impulsive deformation of the shells within experimental scatter.

---

Sosnin E. A.^1,2, Avdeev S. M.¹, Panarin V. A.¹, Tarasenko V. F.¹, Pikulev A. A.³, Tsvetkov V. M.³ The radiative and thermodynamic processes in dbd driven xebr and krbr exciplex lamps // The European Physical Journal D - Atomic, Molecular and Optical Physics. 2011. Т. 62. № 3. С. 405 - 411.

¹ Institute of High Current Electronics SB RAS, Tomsk, Russia
² Tomsk State University, Tomsk, Russia
³ Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

The radiative and thermodynamic parameters of a dielectric barrier discharge XeBr and KrBr excilamp were studied. The power expended in heating the gas mixture and the excilamp bulb was determined by measuring the fast and slow components of a pressure jump. The power consumed by the exilamp was estimated using oscillograms of voltage and current pulses. The maximum UV power and efficiency of a XeBr excilamp were 3,8 W and 7,5%, respectively. For the same conditions the maximum UV power and efficiency of a KrBr excilamp were 1,6 W and 3%, respectively. Analysis of the experimental results shows that at low mixture pressures most of the discharge power is expended in heating the gas and at the elevated pressure the most of the discharge power goes into the generation of acoustic waves and heating of the excilamp bulb walls through electron and ion bombardment. The concept proposed earlier for the energy balance in DBD lamps as thermodynamic systems was verified.

---

Zhernokletov M. V.¹, Kovalev A. E.¹, Komissarov V. V.¹, Novikov M. G.¹, Zocher M. A.², Cherne F. J.² Study of cerium phase transitions in shock wave experiments // Journal of Experimental and Theoretical Physics. 2011. Т. 112. № 2. С. 212 - 219.

¹ Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
² Los Alamos National Laboratory, Los Alamos, New Mexico, USA

Cerium has a complex phase diagram that is explained by the presence of structural phase transitions. Experiments to measure the sound velocities in cerium by two methods were carried out to determine the onset of cerium melting on the Hugoniot. In the pressure range 4 – 37 GPa, the sound velocity in cerium samples was measured by the counter release method using manganin - based piezoresistive gauges. In the pressure range 35 – 140 GPa, the sound velocity in cerium was measured by the overtaking release method using carbogal and tetrachloromethane indicator liquids. The samples were loaded with plane shock wave generators using powerful explosive charges. The onset of cerium melting on the Hugoniot at a pressure of about 13 GPa has been ascertained from the measured elastic longitudinal and bulk sound velocities.

---

Babich L. P., Bochkov E. I. Deterministic methods for numerical simulation of high-energy runaway electron avalanches // Journal of Experimental and Theoretical Physics. 2011. Т. 112.№ 3. С. 494 – 503.

Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

The possibilities of two deterministic methods for describing the kinetics of high - energy runaway electrons ( REs)  are analyzed as alternatives to stochastic methods requiring unrealistically large computing resources in problems of numerical simulation of electric discharges in dense gases involving REs. One of the methods being developed in recent years is based on multigroup equations for the moments of the electron distribution function, while the second method, which is conventionally used to solve problems in gas discharges, is based on the diffusion - drift equation. The modern method of multigroup equations allows one to calculate the RE energy distribution and the spatial RE distribution along the electric force, which are close to these distributions obtained by the Monte Carlo method if the number N of energy groups is chosen properly. The diffusion - drift equation does not give the energy distribution, but its advantage is the possibility of obtaining spatial RE distributions using small computing resources not only along but also perpendicular to the electric force, which are close to those calculated by the Monte Carlo method. To simulate discharges by the method of multigroup equations, it is necessary to know a priori the number N of groups providing good accuracy, the characteristic RE multiplication timete, and the energy runaway threshold ɛth as functions of the electric - field overvoltage. The diffusion - drift equation requires the specification, along with te, of the directed RE velocity and longitudinal and transverse diffusion coefficients calculated by the Monte Carlo method.

---

Buchirina O. A., Derkach I. N., Eremin A. A., L’vov L. V., Sukharev S. A., Chernov I. E. Interferometric studies of the radiation wave front on the luch setup // Plasma Physics Reports. 2011. Т. 37. № 3. С. 232 - 238.

Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

A radial shear interferometer for studying the shape of the wave front and aberrations of the optical system of the Luch setup were designed and created. To improve the interferometric pattern, the interferometer was simulated numerically by using the Fresnel software package. The parameters of the interferometer were optimized. The interferometer allows one to record interferograms of pulsed radiation at the first and second harmonics of a neodymium laser, as well as of continuous IR radiation with a short coherence length. A new method was developed for recovering the wave front by using the WinFringe software for interferograms with a reference front. Aberrations introduced by different parts and the entire optical system of the setup were measured. The wave fronts of the first and second harmonics obtained in full – scale experiments are presented. The experimental results agree with the radiation divergence measured by other methods.

---

Bobrova A. A., Dubinov A. E., Esin M. I., Zolotov S. V., Maksimov A. N., Selemir V. D., Sidorov I. I., Shubin A. Y. Probe measurements of the electron distribution function in an electron-beam - produced ytterbium plasma // Plasma Physics Reports. 2011. Т. 37. № 1. С. 82 - 86.

Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

A no equilibrium anisotropic plasma produced by an electron beam in the residual air with a low content of ytterbium vapor was investigated by the probe method. It is found that a minor ( at a level of a few ppm ) admixture of ytterbium to low-pressure air substantially modifies the electron energy distribution function ( EEDF ): the main peak corresponding to thermal electrons broadens, and new peaks appear. It is shown that the observed change in the EEDF is caused by the low ionization energy of ytterbium, due to which one beam electron can ionize several ytterbium atoms. The new peaks in the EEDF correspond to the final energies of a beam electron after each subsequent ionizing collision with ytterbium atoms.

---

Bat’kov Y. V.¹, Ignatova O. N.¹., Kondrokhina I. N.¹, Malyshev A. N.¹, Nadezhin S. S.¹, Podurets A. M.¹, Raevskii V. A.¹, Skokov V. I.¹, Tyupanova O. A.¹, Zocher M. A.², Preston D. L.² Specific features of the damage nucleation stage under severe loading of copper // Physics of the Solid State. 2011. Т. 53. № 4. С. 768 - 772.

¹ Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
² Los Alamos National Laboratory, Los Alamos, New Mexico, USA

The nucleation and evolution of damage in annealed coarsely crystalline M1 - type copper subjected to fast loading to a pressure P ~ 32 GPa, followed by the action of tensile stresses σp with an intensity of ≈ − 2,0 GPa for a time t ≈ 0,3 – 1,5 μs, have been investigated numerically and experimentally. It has been shown that, at a specific combination of amplitude - time characteristics of the tensile stress pulse, damage localization in some cases at t < 1 ?s has been observed in zones ( ~ 10 – 14 mm in size ) alternating with «dead» zones ( ~ 3 - 5 mm in size ) containing no visible damages. Pores are connected by «yield streamlets». The existing multistage models of fracture kinetics have neither explained nor predicted the formation of a «band» damage structure or the presence of «yield streamlets» in specimens.

---

Sosnin E. A.^1,2, Tarasenko V. F.^1,2, Pikulev A. A.³ Optical characteristics of cylindrical exciplex and excimer lamps excited by microwave radiation // Technical Physics. The Russian Journal of Applied Physics. 2011. Т. 56. № 4. С. 526 - 530.

¹ Institute of High Current Electronics SB RAS, Tomsk, Russia
² Tomsk State University, Tomsk, Russia
³ Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

The object of investigation is the optical characteristics of Br2, Cl2, XeBr, and XeCl excilamps excited by microwave radiation. The power of the microwave discharge is determined from a pressure jump in the bulb of the lamp. Conditions for the effective generation of XeCl* and XeBr* exciplexes in cylindrical lamps are found. The efficiency of generation of these exciplexes equals 7,2 and 7,8%, respectively.

---

Donets E. D.¹, Donets E. E.¹, Syresin E. M.¹., Dubinov A. E.², Makarov I. V.², Sadovoi S. A.², Saikov S. K.², Tarakanov V. P.³  Nonlinear dynamics of longitudinal structures in the electron cloud of a coaxial electron string ion source // Technical Physics. The Russian Journal of Applied Physics. 2011. Т. 56. № 5. С. 690 - 696.

¹ Joint Institute for Nuclear Research, Dubna
² Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
³ Joint Institutes for High Temperature, Russian Academy of Science, Moscow

The results of 2,5 D particle – in - cell simulation of a coaxial electron trap with an internal anode are reported. It is found that, when the circulating current reaches the value of the ultimate vacuum current, first a virtual cathode arises in the trap and then the beam compresses (distributed virtual cathode). The transient preceding the compressed state exhibits complicated nonlinear dynamics, when compressed regions alternate with regions that are in a two - flow state ( phase - space bubbles or phase - space holes) . Physically, phase - space holes are similar to the well - known Bernstein – Greene - Kruskal plasma structures. Three types of phasespace holes with different dynamics (oscillating holes, flying holes, and chaotic holes) are revealed. Consideration of phase - space holes as quasi - particles makes it possible to find several channels of their interaction in pair collisions. The feasibility of the coaxial trap as a source of highly charged ions is analyzed. Although the compressed beam mode provides a larger amount of accumulated electrons compared with the conventional two - flow mode, the mean kinetic energy in the presence of a virtual cathode turns out to be much lower. A way of elevating the mean kinetic energy is suggested that consists in increasing the limit vacuum current in the axial configuration with an internal electrode.

---

Dubinov A. E., Makarov I. V., Sadovoi S. A., Saikov S. K., Tarakanov V. P. Specific features of accumulating electrons in high - current trap // Technical Physics Letters. 2011. Т. 37. № 3. С. 230 - 232.

Russian Federal Nuclear Center (VNIIEF), Sarov, Russia

A symmetric dynamics of the virtual cathode (VC) formation in an electron beam and a scenario for attaining a compressed electron beam state have been numerically simulated. The parameters of this process are determined, including the moment of VC appearance and the total amount of charge accumulated by this moment. The established symmetric scenario qualitatively differs from those previously described in the literature.

Page:

I 1 I

2 I

3 I

4 I