RADIATION LOSS DETERMINATION AT COLLISION OF ELECTRONS WITH LECTRONEGATIVE ATOMS AND IONS IN PLASMA CURRENT SWITCH DISCHARGES. PART II

Specific radiation-loss power values have been determined for a variety of electronegative elements (C, O, F, Cl) as functions of electron temperature and impurity particle concentration. The maximum radiation-loss power level has been registered for chlorine (≤770 W/cm3) at an electron/impurity density of 1014 cm-3. The minimum radiation-loss power level for the other three elements lies in the range from 0.4 to 2 W/cm3. Considerable radiation losses due to the presence of electronegative elements in the interelectrode discharge may lead to its destabilization, to the change in the plasma parameters (ne, Te), and eventually, to degradation of the current-voltage characteristic of the plasma current switch.

Microscopic Derivation of the Fröhlich Hamiltonian for the Bose Polaron in the Mean-Field Limit

We consider the quantum mechanical many-body problem of a single impurity particle immersed in a weakly interacting Bose gas. The impurity interacts with the bosons via a two-body potential. We study the Hamiltonian of this system in the mean-field limit and rigorously show that, at low energies, the problem is well described by the Fröhlich polaron model.

Impurity temperature screening in stellarators close to quasisymmetry

Impurity temperature screening is a favourable neoclassical phenomenon involving an outward radial flux of impurity ions from the core of fusion devices. Quasisymmetric magnetic fields lead to intrinsically ambipolar neoclassical fluxes that give rise to temperature screening for low enough $\unicode[STIX]{x1D702}^{-1}\equiv d\ln n/d\ln T$ . In contrast, neoclassical fluxes in generic stellarators will depend on the radial electric field, which is predicted to be inward for ion-root plasmas, potentially leading to impurity accumulation. Here, we examine the impurity particle flux in a number of approximately quasisymmetric stellarator configurations and parameter regimes while varying the amount of symmetry breaking in the magnetic field. For the majority of this work, neoclassical fluxes have been obtained using the SFINCS drift-kinetic equation solver with electrostatic potential $\unicode[STIX]{x1D6F7}=\unicode[STIX]{x1D6F7}(r)$ , where $r$ is a flux-surface label. Results indicate that achieving temperature screening is possible, but unlikely, at low-collisionality reactor-relevant conditions in the core. Thus, the small departures from symmetry in nominally quasisymmetric stellarators are large enough to significantly alter the neoclassical impurity transport. A further look at the magnitude of these fluxes when compared to a gyro-Bohm turbulence estimate suggests that neoclassical fluxes are small in configurations optimized for quasisymmetry when compared to turbulent fluxes.

ANALYSIS OF THE MATHEMATICAL MODEL OF THE WASTE OIL PURIFICATION IN A DIESEL LOCOMOTIVE ENGINE

The article analyses a mathematical model of the waste oil purification in the oil system of a diesel locomotive engine. Waste oil purification takes place directly in the engine during its operation, which enables to reduce considerably the time taken to purify, and to decrease the concentration of impurities in the oil. In the proposed system for automatic control of waste oil purification, the main monitored parameters are pressure and temperature of the oil being purified. During analyzing the analytical solution of the system, the authors studied an increase in the concentration of impurity particles, the behavior of particle velocities in the centrifuge, and determined assumptions, within the framework of which the velocity of impurity particles was simulated. The influence of the impurity particle shape in the oil was taken into account in making these assumptions.