Ultracold plasma expansion in quadrupole magnetic field.

We present simulation results of ultracold Sr plasma expansion in a quadrupole magnetic field by means of molecular dynamics. An analysis of plasma evolution influenced by a magnetic field is given. Plasma confinement time behavior under variation of magnetic field strength is estimated. Similarity of the time dependence of the concentration and distribution of ion velocities against the parameters of the plasma and magnetic field is established. Simulation results are in agreement with the experimental ones.

Ion wave formation during ultracold plasma expansion.

We present the results of a direct simulation of the expansion of a two-component ultracold plasma for various numbers of particles, densities, and electron temperatures. A description of the expansion process common to all plasma parameters is given. After the escape of fast electrons from the plasma cloud, the excess positive charge is localized at the outer boundary, in a narrow layer. This layer has a characteristic front shape with a sharp drop in the charge concentration. The charged layer retains the remaining electrons during the entire expansion process. As the plasma expands, the speed of movement of the charged layer becomes constant and significantly exceeds the sonic speed of ions. In addition, the dependence of the radial velocity of ions on the radius acquires a self-similar character long before the final stage of expansion. Based on the calculation results, equations and self-similar solutions are obtained. General dependencies on plasma parameters are determined, which are compared with experimental data.

[A comparative evaluation of the efficacy of the traditional combination of high-frequency and intermittent high-frequency artificial ventilation of the lungs in patients with parenchymatous acute respiratory insufficiency]. / Sravnitel'naia otsenka éffektivnosti traditsionnoi sochetannoi vysokochastotnoi i preryvistoi vysokochastotnoi iskusstvennoi ventiliatsii legkikh u bol'nykh s parenkhimatoznoi ostroi dykhatel'noi nedostatochnost'iu.

Conventional controlled lung ventilation (CLV) with positive end expiratory pressure (PEEP) (Con CLV), combined high-frequency CLV (Com HF CLV) and intermittent high-frequency CLV with PEEP (Int HF CLV) have been performed in 43 patients with parenchymatous acute respiratory failure (ARF). It has been established that Int HF CLV significantly increases PaO2 in patients with focal damages of the lung parenchyma and effective compliance (Ceff) > 0.033 l/cm H2O. Com HF CLV increases significantly PaO2 and lung compliance in patients with disseminated lung damages and Ceff < 0.030 l/cm H2O and has marked consequences. Different efficacy of various types of HF CLV under study may be to some extent accounted for by different intraalveolar maximum pressure, which (as it has been shown on the lung model) is higher in Com HF CLV and lower in Con CLV and Int HF CLV.

[Intensification of gas exchange in high-frequency artificial ventilation]. / K voprosu ob intensifikatsii gazoobmena pri vysokochastotnoi IVL.

Jet high-frequency artificial ventilation produces oscillations of some parts of the chest wall, which in its turn transmits oscillations to the lung parenchyma. It results in the mix-up of the gas in the alveolar space, which leads to the increase in the gradient of oxygen concentration on the alveolar membranes, thus, augmenting oxygen saturation of the blood. The effect is the same when oscillation artificial ventilation is performed, owing to the provocation of the oscillations amplified by the resonance in the natural acoustic circuit, formed by the adjacent parts of the chest and lung parenchyma. Derangement of the exudative adhesion to the bronchi epithelial tissue intensifies gas exchange, when the oscillations are generated in the lungs. It facilitates the removal of the exudate and lets the air into the previously obstructed parts of the lungs. Clinical studies confirm the effect of the increase in the blood oxygenation (by average 20%) at the feeding air column by pneumatic oscillations in the range of 65 Hz, when traditional artificial ventilation is performed.