Персона: Гасилов, Владимир Анатольевич
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Владимир Анатольевич
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- ПубликацияОткрытый доступLaser-heated capillary discharge plasma waveguides for electron acceleration to 8 GeV(2020) Gonsalves, A. J.; Nakamura, K.; Benedetti, C.; Pieronek, C. V.; Bagdasarov, G.; Gasilov, V.; Гасилов, Владимир АнатольевичA plasma channel created by the combination of a capillary discharge and inverse Bremsstrahlung laser heating enabled the generation of electron bunches with energy up to 7.8GeV in a laser-driven plasma accelerator. The capillary discharge created an initial plasma channel and was used to tune the plasma temperature, which optimized laser heating. Although optimized colder initial plasma temperatures reduced the ionization degree, subsequent ionization from the heater pulse created a fully ionized plasma on-axis. The heater pulse duration was chosen to be longer than the hydrodynamic timescale of approximate to 1ns, such that later temporal slices were more efficiently guided by the channel created by the front of the pulse. Simulations are presented which show that this thermal self-guiding of the heater pulse enabled channel formation over 20cm. The post-heated channel had lower on-axis density and increased focusing strength compared to relying on the discharge alone, which allowed for guiding of relativistically intense laser pulses with a peak power of 0.85 PW and wakefield acceleration over 15 diffraction lengths. Electrons were injected into the wake in multiple buckets and times, leading to several electron bunches with different peak energies. To create single electron bunches with low energy spread, experiments using localized ionization injection inside a capillary discharge waveguide were performed. A single injected bunch with energy 1.6GeV, charge 38 pC, divergence 1 mrad, and relative energy spread below 2% full-width half-maximum was produced in a 3.3cm-long capillary discharge waveguide. This development shows promise for mitigation of energy spread and future high efficiency staged acceleration experiments.
- ПубликацияТолько метаданныеDifference Schemes of Consistent Approximation of the Stress-Strain State and Energy Balance of a Medium(2020) Podryga, V. O.; Ladonkina, M. E.; Voloshin, A. S.; Boykov, D. S.; Poveshchenko, Y. A.; Gasilov, V. A.; Повещенко, Юрий Андреевич; Гасилов, Владимир Анатольевич© 2020, Pleiades Publishing, Ltd.Abstract: Using the support operator technique for two-dimensional problems of the elasticity theory we constructed integrally consistent approximations of the components of the strain tensor and the elastic energy of the medium for the equations of the elasticity theory in terms of displacements. Approximations are constructed for the case of irregular difference grids in the R–Z plane of a cylindrical coordinate system. We use the limiting process assuming that the azimuthal angle tends to zero for passing from the full three-dimensional approximations to the two-dimensional approximations in the R–Z plane. The used technique preserves the divergent form, self-adjointness, and sign-definiteness of the two-dimensional approximations. These properties are inherent in their 3D predecessors corresponding to the operators in the governing differential equations.
- ПубликацияТолько метаданныеCompletely Conservative Difference Schemes for Fluid Dynamics in a Piezoconductive Medium with Gas Hydrate Inclusions(2020) Podryga, V. O.; Rahimly, P. I.; Gasilov, V. A.; Poveshchenko, Y. A.; Гасилов, Владимир Анатольевич; Повещенко, Юрий Андреевич© 2019, Pleiades Publishing, Ltd.Abstract: The dynamics equations for a two-component fluid in a porous medium with gas hydrate inclusions are approximated on a structurally irregular difference grid. The case of a thermodynamically equilibrium model is considered. The support operator method is used to construct a family of completely conservative two-level difference schemes. The time approximation is based on expressions “weighted” according to grid time levels with weighting factors that generally vary in space. For a difference fluid dynamics problem, an algorithm based on splitting into physical processes is proposed.
- ПубликацияТолько метаданныеIntegral-Consistent Numerical Technique for Self-gravitating Medium Model(2019) Sharova, Y. S.; Smirnova, N. S.; Podryga, V. O.; Poveshchenko, Y. A.; Gasilov, V. A.; Повещенко, Юрий Андреевич; Гасилов, Владимир Анатольевич© 2019, Springer Nature Switzerland AG.The supercompression of matter caused by gravitational coupling or self-gravitational forces leads to density growth by several orders in magnitude. Keeping in mind the importance of self-gravitation in astrophysical processes like supernovae star evolution we consider it reasonable to develop a numerical technique based on the consistent approximation to the terms describing gravitational energy transfer into the kinetic energy of a matter in the star along its life cycle. The so-called completely conservative gas-dynamics difference schemes including the gravitation effects are the proper numerical technique able to simulate correctly the problems concerning gravitational coupling effects. The accounting for gravitational forces in the construction of completely conservative difference schemes is a significant complication. In the paper, we propose an integrally-consistent difference scheme that utilizes the method of support difference operators thus providing a possibility to conform the balance between kinetic and gravitational energy increments or losses. According to this method, we use the result of the total gravitational energy varying and construct the symmetrized strain rate tensor as the base operator. The result of varying the gravitational energy of the system is a discrete convolution of the Newton gravitational tensor in the difference media under study, which exhaustively answers all the gravitational processes unfolding against the background of the hydrodynamic motion of matter. The symmetrized strain tensor governs the kinematic motion in a considered system. The conjugate operator related to the convolution of these tensors automatically gives the approximation to the gravitational forces acting in the interior of the balance volume of the difference model built via the support operator approach.
- ПубликацияТолько метаданныеIntegral-consistent numerical technique for gravitationally coupled medium model(2019) Sharova, Yu. S.; Podryga, V. O.; Poveshchenko, Y. A.; Gasilov, V. A.; Повещенко, Юрий Андреевич; Гасилов, Владимир Анатольевич© 2019 Author(s).The supercompression of matter caused by gravitational coupling, or self-gravitational forces, leads to density growth by several orders in magnitude. Keeping in mind the importance of self-gravitation in astrophysical processes like supernovae star evolution we consider it reasonable to develop a numerical technique based on the consistent approximation to the terms describing gravitational energy transfer into the kinetic energy of a matter in the star along its life cycle. In the paper, we propose an integrally-consistent difference scheme that utilizes the method of support difference operators thus providing a possibility to conform the balance between kinetic and gravitational energy increments or losses. According to this method, we use the result of the total gravitational energy varying and construct the symmetrized strain rate tensor as the base operator. The result of varying the gravitational energy of the system is a discrete convolution of the Newton gravitational tensor in the difference media under study, which exhaustively answers all the gravitational processes unfolding against the background of the hydrodynamic motion of matter. The symmetrized strain tensor governs the kinematic motion in a considered system. The conjugate operator related to the convolution of these tensors automatically gives the approximation to the gravitational forces acting in the interior of the balance volume of the difference model built via the support operator approach.
- ПубликацияОткрытый доступIntegrally-consistent techniques for modeling of magneto-hydrodynamic phenomena in gravitationally-bounded structures(2019) Poveshchenko, Y. A.; Sharova, Y. S.; Podryga, V. O.; Gasilov, V. A.; Гасилов, Владимир Анатольевич© 2019 Author(s).We develop an integral-consistent difference scheme by means of a support-operator method. The basic difference operator is constructed via the first variation of the energy functional related to the coupled matter-electromagnetic field system. This operator gives rise to other difference approximations in our discrete model. It can be represented as a discrete convolution of Maxwell stress tensor. Using the support-operator approximation we construct this operator in a form which naturally provides the Lorentz force approximation.
- ПубликацияТолько метаданныеHomogeneous Difference Schemes for the Coupled Problems of Hydrodynamics and Elasticity(2019) Tsygvintsev, I. P.; Krukovskiy, A. Y.; Poveshchenko, Y. A.; Gasilov, V. A.; Повещенко, Юрий Андреевич; Гасилов, Владимир АнатольевичFinite-di (R) erence approximations of elastic forces on the staggered moving grid were constructed. For the displacement vectors at the irregular grids in which topological and geometrical structures are subjected to minimal reasonable restrictions, with regard to the nitedi (R) erence schemes of the elasticity theory problems, approximations of the vector analysis operators in plane and cylindrical geometries were constructed. Taking into account the energy balance of the medium, the families of integral consistent approximations of the vector analysis operators, which are su +/- cient for the discrete modeling of these processes considering the space curvature caused by the cylindrical geometry of the system, were built. The schemes, both using a stress tensor in the full form and dividing it into volumetric and deviator components, were studied. This separation is used to construct homogeneous equations that are applicable for solid body and vaporized phase. The linear theory of elasticity was used. The resulting expressions for the elastic forces were presented in the explicit form for two-dimensional degrees at and axisymmetric geometries for a mesh consisting of triangular and quadrangular cells. Generalization of the method for other cases (non-linear strain tensor, non-Hookean relation between strain and stress, full 3D geometry, etc.) can be performed by analogy, but this was not a subject of the current paper. Using the model problem, comparison between di (R) erent temporal discretizations for the obtained ordinary di (R) erential equations system was carried out. In particular, we considered fully implicit approximation, conservative implicit approximation (Crank Nicolson method), and explicit approximation, which is similar to the \leap-frog" method. The analysis of full energy imbalance and calculation costs showed that the latter is more advantageous. The analysis of the e (R) ectiveness of various temporal approximations was performed via numerical experiments.
- ПубликацияТолько метаданныеInteraction of plasma flows and magnetic field with the formation of a shock wave in nested arrays(2019) Aleksandrov, V. V.; Branitsky, A. V.; Boldarev, A. S.; Grabovskiy, E. V.; Gasilov, V. A.; Гасилов, Владимир Анатольевич© EPS 2019. All rights reserved.The results of plasma compression studies of nested wire and fiber arrays with current flowing through them are presented in this work. Experiments were made on the Angara-5-1 facility with current up to 4 MA. Current implosion of nested arrays represents a unique opportunity to simulate the interaction of a plasma flow with a magnetic field. Different plasma flow regimes in the space between the inner and outer arrays were obtained: sub-Alfven (VrV?) and a mode with the formation of a transition region-shock wave (SW)-between the arrays, depending on the radii ratio of the inner and outer arrays. The dependence of these flow regimes on the plasma production rate of the inner and outer arrays is shown. At certain parameters of nested arrays, a quasi-closed shell is formed in the azimuthal direction around the inner array. At the same time, the plasma of the outer array surrounds the inner and stabilizes its compression. The suppression of MRT instabilities during plasma compression of the inner array leads to the formation of a stable, compact Z-pinch and the generation of a short-time soft X-ray pulse.
- ПубликацияТолько метаданныеProgress in researching the implosion of nested arrays of mixed composition and the generation of soft X-ray power pulse(2022) Mitrofanov, K. N.; Aleksandrov, V. V.; Branitski, A. V.; Grabovskiy, E. V.; Gasilov, V. A.; Гасилов, Владимир Анатольевич© 2022 IOP Publishing Ltd.The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft X-ray radiation (SXR), carried out on a pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances m˙ (in μg(cm2 ns)-1) (Mitrofanov et al 2020 Plasma Phys. Rep. 46 1150-80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov et al 2018 Plasma Phys. Rep. 44 203-35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power P SXRmax∼10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays: P SXRmax∼5 TW and FWHM ∼10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.
- ПубликацияТолько метаданныеPetawatt Laser Guiding and Electron Beam Acceleration to 8 GeV in a Laser-Heated Capillary Discharge Waveguide(2019) Gonsalves, A. J.; Nakamura, K.; Daniels, J.; Benedetti, C.; Bagdasarov, G.; Gasilov, V.; Гасилов, Владимир АнатольевичGuiding of relativistically intense laser pulses with peak power of 0.85 PW over 15 diffraction lengths was demonstrated by increasing the focusing strength of a capillary discharge waveguide using laser inverse bremsstrahlung heating. This allowed for the production of electron beams with quasimonoenergetic peaks up to 7.8 GeV, double the energy that was previously demonstrated. Charge was 5 pC at 7.8 GeV and up to 62 pC in 6 GeV peaks, and typical beam divergence was 0.2 mrad.