Direct observation of anomalously low longitudinal electron heat conductivity in the course of collective relaxation of a high-current relativistic electron beam in plasma

Аржанников, А. В.; Astrelin, V. T.; Burdakov, A. V.; Иванов, И. А.; Koǐdan, V. S.; Mekler, K. I.; Поступаев, В. В.; Rovenskikh, A. F.; Polosatkin, S. V.; Sinitskii, S. L.

doi:10.1134/1.1581960

Cited by 35 publications

(15 citation statements)

References 3 publications

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“…Figure 3 shows the distributions of velocity, density, electron temperature, and total temperature at the times t = 1, 2, 3, and 4 µsec (curves 1, 2, 3, and 4, respectively) for the prescribed distribution of the magnetic field. In accordance with the hypothetical mechanism of ion acceleration and with the GOL-3 experimental data (see [11]), the plasma is heated nonuniformly by the electron beam because of the magnetic-field nonuniformity: the temperature increases rather appreciably at the edges of the mirror system and to a smaller extent at the center of the well. The nonuniformity of pressure results in acceleration of the plasma toward the center of the cell.…”

Section: Simulation Of Plasma Heating and Motionsupporting

confidence: 75%

“…To test the algorithms and their capability in modeling the plasma-heating mechanism within the framework of the proposed physical model [2], we simulated plasma dynamics under conditions of a special GOL-3 experiment with a single magnetic cell [11,12]. Undisturbed values of the sought quantities were initially (t = 0) set in a channel of length L = 12.32 m: n = 1, V = 0, and T i = T e = 0.001.…”

Section: Simulation Of Plasma Heating and Motionmentioning

confidence: 99%

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Numerical Simulation of Plasma Dynamics in a Nonuniform Magnetic Field

Astrelin

Burdakov

Kovenya

et al. 2006

J Appl Mech Tech Phys

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An efficient algorithm is proposed enabling numerical simulations of plasma dynamics in a nonuniform magnetic field. The present numerical data are in good agreement with experimental data obtained in a GOL-3 setup and with previous simulations. The experimentally observed effect of fast transfer of energy to ions is confirmed.Introduction. In GOL-3 experiments on plasma heating and confinement in a multiple-mirror trap, fast heating of plasma is ensured by a relativistic electron beam with an energy up to 1 MeV (current up to 30 kA, duration up to 8 µsec, and energy up to 120-150 kJ) [1]. A deuterium-plasma column of density n ≈ 10 15 cm −3 , length of 12.3 m, and diameter of 4-5 cm is formed in a corrugated magnetic field consisting of 55 cells, each 22 cm long, with a magnetic ratio B max /B min = 5.2/3.2 T. The plasma column is confined by edge magnetic mirrors with a magnetic field of B max ≈ 9 T. Collective heating of the plasma by the beam proceeds under conditions of developed Langmuir turbulence and lengthwise electron heat conduction being suppressed by turbulent electric fields; in the corrugated field, such a situation gives rise to periodic longitudinal modulation of the electron temperature and pressure. The pressure gradient initiates formation and acceleration of plasma flows toward the centers of magnetic cells. Experiments showed that collisions between the flows result in neutron outbursts of thermonuclear nature, followed by fast thermalization of the directional energy of plasma motion accompanied by neutron emission [1]. Measurements confirmed a fast growth of ion energy (up to 1-2 keV for the period of beam action), which could not be explained by the Coulomb electron-ion collisions. To investigate the above-mentioned mechanism of fast transfer of energy to ions, the dynamics of a two-component plasma was numerically simulated in [2] with the use of traditional computational algorithms [3] in the hydrodynamic approximation, because the ion temperature in the plasma generated by a direct discharge in deuterium is low at the initial stage of heating and the free path of ions is much shorter than the length of one cell in the multiple-mirror trap. As a numerical analysis showed and an experiment confirmed [1], the dynamics of the plasma under such conditions is accompanied by generation of high-amplitude nonlinear waves, which requires more efficient algorithms to be developed to model the process of interest.To numerically solve strongly nonlinear problems, algorithms with enhanced stability, capable of predicting solutions over long time intervals, are required (see [4]). Such algorithms can be developed on the basis of predictorcorrector schemes, where the required stability is ensured at the predictor stage and conservatism is re-established at the corrector stage, thus providing for satisfaction of differential conservation laws. A predictor-corrector scheme was proposed in [5,6] for the numerical solution of gas-dynamic equations. The technique of splitting in terms of physical processes...

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Section: Simulation Of Plasma Heating and Motionsupporting

confidence: 75%

Section: Simulation Of Plasma Heating and Motionmentioning

confidence: 99%

Numerical Simulation of Plasma Dynamics in a Nonuniform Magnetic Field

Astrelin

Burdakov

Kovenya

et al. 2006

J Appl Mech Tech Phys

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“…The greater the value of k 00 , the faster the electron and ion temperatures become equalized, after which the plasma can be considered as one-fluid and one-temperature. The results of the present calculations offer an adequate description of the physics of the phenomenon under study and are in good qualitative and quantitative agreement with available results of physical and numerical experiments [1][2][3][4][5]8].…”

supporting

confidence: 74%

“…Rapid heating of ions in the plasma to a temperature commensurable with the electron temperature is observed thereby. This heating can be attributed to a collective character of ion acceleration under the gradient of the electron pressure of the plasma rather than to electron-ion collisions [1,2]. To study the above-described mechanism of fast transfer of energy from electrons to ions, Arzhannikov et al [3] and Astrelin et al…”

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confidence: 99%

Numerical simulation of plasma motion in a magnetic field. Two-dimensional case

Astrelin

Kovenya

Kozlinskaya

2007

J Appl Mech Tech Phys

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A model of dynamics and heating of a plasma cloud in a magnetic field is considered in a twotemperature approximation. Based on a predictor-corrector-type implicit difference scheme, spreading of a plasma cloud in an external magnetic field is numerically simulated, and the influence of this field on spread dynamics is evaluated. Introduction.In experiments on plasma heating and confinement in a multiple-mirror trap in a GOL-3 setup, rapid heating of the plasma can be ensured by using a relativistic electron beam. Experiments demonstrated that the electron component of the plasma is heated under conditions of a developed Langmuir turbulence suppressing electron-type heat conduction. Rapid heating of ions in the plasma to a temperature commensurable with the electron temperature is observed thereby. This heating can be attributed to a collective character of ion acceleration under the gradient of the electron pressure of the plasma rather than to electron-ion collisions [1,2]. To study the above-described mechanism of fast transfer of energy from electrons to ions, Arzhannikov et al. [3] and Astrelin et al.[4] modeled the dynamics of a two-component plasma in a one-dimensional hydrodynamic approximation by different numerical methods. Numerical and experimental results show that plasma motion under these conditions is accompanied by emergence of high-amplitude nonlinear waves. This required a special numerical method to be developed [4,5], which would be stable in a wide range of plasma parameters and sufficiently accurate for solving problems of this class.A refined two-dimensional model is proposed in the present paper to describe the motion of a one-fluid two-temperature plasma with allowance for the effects of heat conduction, electrical conduction, thermal forces, and friction forces arising in collisions between ions and electrons. A predictor-corrector-type implicit difference scheme was proposed for the numerical solution of magnetohydrodynamic problems in one-dimensional and multidimensional approximations [5,6]. This model is extended below to the case of a two-temperature plasma. The problem of spreading of an originally spherical hot plasma cloud under the action of hydrodynamic forces and a magnetic field is solved. At the present stage of research, dissipative effects are neglected, but it is assumed that the initial ion and electron temperatures may be different. The influence of an external magnetic field and initial temperature distribution within wide ranges of their values on the characteristics of plasma motion is studied.Physicomathematical Model. The problem of propagation of a dense plasma cloud in an external magnetic field is considered. The original plasma cloud is assumed to have a spherical shape and to have parameters (pressure, density, and temperature) whose values are several orders higher than the background level. Under the action of hydrodynamic and magnetic pressures, this cloud starts spreading over the background plasma. The flow is assumed to be axisymmetric and is simulated ...

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“…The suggestion of anomalous scattering was not trivial, because primary beam-pumped Langmuir turbulence is too fast to effectively interact with slow bulk electrons and other usual mechanisms for anomalous resistivity [19] should not work at the discussed parameters. Later, special experiments [20] directly demonstrated transport anomalities during the beam injection time. In this experiment, a magnetic well was formed in the central part of the solenoid with uniform magnetic field (Fig.…”

Section: Turbulent Suppression Of Axial Electron Heat Transportmentioning

confidence: 99%

Multiple-mirror trap: Milestones and future

Burdakov

Поступаев

2016

AIP Conference Proceedings

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Abstract.A fusion reactor concept on the basis of a linear trap is developing in BINP. These studies incorporate multiple-mirror sections which should reduce significantly longitudinal plasma losses from a confinement zone. In the paper, physics on the multiple-mirror confinement relevant to plasma behavior at reactor conditions will be discussed. Basic results were received in the GOL-3 multiple-mirror trap in which plasma of 10 21 m -3 density was heated by a highpower electron beam up to 2 -4 keV temperature. The key milestones were: the demonstration of effective plasma heating by the electron beam due to collective effects, the achievement of theoretically predicted level of energy confinement time under optimal conditions, and finally, the discovery of a bounce instability that improves longitudinal confinement. Direct demonstration of a confinement improvement by multi-mirror sections in the magnetic configuration relevant to the reactor one will be done in the GOL-NB facility that will be created in BINP. In addition, a new plasma device SMOLA with a helical multiple-mirror magnetic field for an active confinement control is discussed.

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Direct observation of anomalously low longitudinal electron heat conductivity in the course of collective relaxation of a high-current relativistic electron beam in plasma

Cited by 35 publications

References 3 publications

Numerical Simulation of Plasma Dynamics in a Nonuniform Magnetic Field

Numerical Simulation of Plasma Dynamics in a Nonuniform Magnetic Field

Numerical simulation of plasma motion in a magnetic field. Two-dimensional case

Multiple-mirror trap: Milestones and future

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