Effect of the magnetic field on the energy of deuterium ions accelerated in the collision of magnetosonic shock waves

A study is made of the effect of the initial magnetic field magnitude on the energy of deuterium ions accelerated in the collision of two magnetosonic shock waves propagating in a deuterium plasma quasi-perpendicularly to the magnetic field. Experiments were carried out at a constant plasma density of ?2.5×10¹³ cm^?3. It is found that, as the external magnetic field decreases from 1.4 to 0.7 T and, accordingly, the magnetic Mach number increases from 1.02 to 2.3, the energy of accelerated ions increases from 3.2 to 7.5 MeV. The maximum number of accelerated ions attains 10⁵–10⁶ particles per shot.     

Solitary fast magnetosonic waves propagating obliquely to the magnetic field in cold collisionless plasma

Solutions describing solitary fast magnetosonic (FMS) waves (FMS solitons) in cold magnetized plasma are obtained by numerically solving two-fluid hydrodynamic equations. The parameter domain within which steady-state solitary waves can propagate is determined. It is established that the Mach number for rarefaction FMS solitons is always less than unity. The restriction on the propagation velocity leads to the limitation on the amplitudes of the magnetic field components of rarefaction solitons. It is shown that, as the soliton propagates in plasma, the transverse component of its magnetic field rotates and makes a complete turn around the axis along which the soliton propagates.     

Current shunting and formation of stationary shock waves during electric explosions of metal wires in air

Results of experiments on the generation of shock waves during electric explosions of fine copper and tungsten wires in air are analyzed. The generation mechanism of stationary shock wave by a plasma piston formed during the shunting breakdown of the electrode gap in the course of a wire explosion is investigated. The role of structural elements of such discharges, such as the core, corona, and wire environment, is analyzed.     

Inflation waves induced by axial acceleration of the aorta

The phenomenon of high-amplitude inflation waves resulting from a sharp axial acceleration of the aorta, as may occur in road accidents, is investigated theoretically. The aorta is modeled as an axisymmetric tapered membranic shell (tube) made of an incompressible, nonlinear viscoelastic material with cylindrical orthotropy. It is filled with an inviscid, incompressible fluid whose flow is considered as quasi-one dimensional along the tube axis. The equations of motion of the tube and of the fluid are solved numerically, by using a two-step explicit scheme, for several axial acceleration profiles. The solutions shows that an inflation wave is generated and it propagates in opposite direction to that of the acceleration. The wall stresses, deformations and their time derivatives as well as fluid velocity and pressure are determined along the tube at different time intervals. Peak axial and circumferential stresses are high, with the latter far exceeding the former. These stresses may cause rupture of the aorta.     

Formation of a steady-state shock front of a fast magnetosonic wave in a turbulent plasma

The question of the existence of a steady-state shock front of a fast magnetosonic wave propagating across the magnetic field against the background of turbulent Alfvén waves is considered. It is shown that the steady-state shock front can form as a result of energy transfer from the turbulent Alfvén wave to the fast magnetosonic wave.     

Collective ion acceleration during the decay of a high-current Z-pinch

A study is made of the Z-pinch plasma expansion after the current is switched off. Measurements were carried out in experiments on the implosion of tungsten wire arrays in the Angara-5-1 facility. It is found experimentally that, at a distance of 2 m from the pinch, the ion velocity in the expanding Z-pinch plasma is about (2.5–4.0) × 10⁷ cm/s, which substantially exceeds the thermal velocity of tungsten ions. A model describing the plasma expansion process is proposed that is based on the ambipolar acceleration mechanism. The results of numerical simulations are compared with the experimental data.     

alphaC domains of fibrinogen molecules as the structures accelerating fibrin assembly

Preparation of monomeric fibrin lacking intact alpha C-domains (monomeric X1-fragment), but fully clottable, is described. The assembly process of both monomeric fibrin and monomeric X1-fragment has been studied by electron microscopy and light scattering methods. It was shown that both proteins form similar fibrils with characteristic cross-banding. Upon dilution a sharp elevation of the differences between the assembly rates of monomeric X1-fragment and monomeric fibrin was revealed. The results obtained show that alpha C-domains take part in fibrin clot formation not as structural components but as the factor accelerating the ordered assembly of complex fibrin structure. The possible mechanism of alpha C-domains participation in fibrin clot formation are regarded.     

Measurements of the load resistance of a poloidal antenna and the phase velocity of fast magnetosonic waves during ICR plasma heating in the L-2M stellarator

The propagation and damping of waves excited by a poloidal antenna in a hydrogen plasma at the ion cyclotron resonance (ICR) frequency were investigated. The longitudinal wavenumber and damping length of waves excited in the ohmically heated plasma of the L-2M stellarator, the dependence of the damping length of fast magnetosonic waves on the magnetic field strength, and the dependence of the antenna load resistance on the plasma density were measured. It is the first time that such complex measurements were performed in experiments on ICR heating of a hydrogen plasma at the fundamental harmonic of the ion gyrofrequency in toroidal magnetic confinement systems.     

Simulation of thermoregulation in serotonin-depleted rats subjected to acceleration fields

A computer simulation of thermoregulation in mammals during and following exposure to hypergravitational fields is developed. This simulation includes the effects of a neurotransmitter, serotonin, and the initial transients of the system when the animal is first placed in a hypergravitational field. Experimental data on the response of rats to serotonin depletion helps place the site at which serotonin acts in the model.     

On the formation of unique dissipative structures

We consider a simple model for the formation of dissipative structures. In general there exists a multitude of stable final states. We show, however, that when the diffusion constant increases during the development of the system, a stationary state is reached which does not depend on the choice of initial conditions. We also show that a uniquely defined final state builds up when the system is initially strongly excited on one side.     

Effects of centimeter waves on the immune system of mice in endotoxic shock

The effects of centimeter waves (8.15-18 GHz, 1 microW/cm2, 1 h daily for 10 days; MW) on the production of the tumor necrosis factor alpha, interleukin-lalpha, interleukin-1beta, interleukin-2, and the expression of interleukin-6, interleukin-10, interferon-gamma, nitric oxide and HSP27, HSP72 and HSP90alpha in mice irradiated before or after LPS injection were studied. An acute endotoxic model was produced by a single LPS injection. The effects of microwaves on nitric oxide, interleukin-6, tumor necrosis factor-alpha, and interferon-gamma were dependent on the functional status of exposed animals. Thus, an exposure of healthy mice to microwaves for 10 days was followed by a decrease in nitric oxide and interferon-gamma production, and an increase in the production of the tumor necrosis factor-alpha and interleukin-6. On the contrary, an exposure to MW before intoxication resulted in an increase in the synthesis of nitric oxide and interferon-gamma as well as a decrease in the concentration of the tumor necrosis factor-alpha and interleukin-6 in blood of mice in endotoxic shock. When microwave exposure was used after LPS injection, it did not provide any protective effect, and preliminary irradiation enhanced the resistance of the organism to endotoxic shock.     

Dependence of the ion energy on the parameters of the laser pulse and target in the radiation-pressure-dominated regime of acceleration

When the dominant mechanism for ion acceleration is the laser radiation pressure, the conversion efficiency of the laser energy into the energy of relativistic ions may be very high. Stability analysis of a thin plasma layer accelerated by the radiation pressure shows that Raleigh-Taylor instability may enhance plasma inhomogeneity. In the linear stage of instability, the plasma layer decays into separate bunches, which are accelerated by the radiation pressure similarly to clusters accelerated under the action of an electromagnetic wave. The energy and luminosity of an ion beam accelerated in the radiation-pressure-dominated regime are calculated.