Simulation of discharge impulses in GTE capacitance ignition systems

A possibility of enhancing the energy efficiency of the capacitance ignition system by realizing the batch mode of discharge impulse generation is substantiated. Using the numerical simulation methods, a problem is solved to study the voltage-current characteristics of such discharge units as a spark discharger and a spark plug and peculiarities of discharge formation in them; the batch mode is simulated with proper account for the influence of discharge-recurrence rate upon dynamics of electric strength recovery in the discharge units. A possibility of optimizing the capacitance ignition system parameters is theoretically evaluated to provide the maximum possible quantity of discharge impulse packet energy as well as the value of their peak capacity at the specified values of supply source power, discharge-recurrence rate, and total voltage of the entire ignition system.     

The ARTEMIS Mission

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon??s Interaction with the Sun (ARTEMIS) mission is a spin-off from NASA??s Medium-class Explorer (MIDEX) mission THEMIS, a five identical micro-satellite (hereafter termed ??probe??) constellation in high altitude Earth-orbit since 17 February 2007. By repositioning two of the five THEMIS probes (P1 and P2) in coordinated, lunar equatorial orbits, at distances of ??55?C65 R _E geocentric (??1.1?C12 R _L selenocentric), ARTEMIS will perform the first systematic, two-point observations of the distant magnetotail, the solar wind, and the lunar space and planetary environment. The primary heliophysics science objectives of the mission are to study from such unprecedented vantage points and inter-probe separations how particles are accelerated at reconnection sites and shocks, and how turbulence develops and evolves in Earth??s magnetotail and in the solar wind. Additionally, the mission will determine the structure, formation, refilling, and downstream evolution of the lunar wake and explore particle acceleration processes within it. ARTEMIS??s orbits and instrumentation will also address key lunar planetary science objectives: the evolution of lunar exospheric and sputtered ions, the origin of electric fields contributing to dust charging and circulation, the structure of the lunar interior as inferred by electromagnetic sounding, and the lunar surface properties as revealed by studies of crustal magnetism. ARTEMIS is synergistic with concurrent NASA missions LRO and LADEE and the anticipated deployment of the International Lunar Network. It is expected to be a key element in the NASA Heliophysics Great Observatory and to play an important role in international plans for lunar exploration.     

ARTEMIS Science Objectives

NASA??s two spacecraft ARTEMIS mission will address both heliospheric and planetary research questions, first while in orbit about the Earth with the Moon and subsequently while in orbit about the Moon. Heliospheric topics include the structure of the Earth??s magnetotail; reconnection, particle acceleration, and turbulence in the Earth??s magnetosphere, at the bow shock, and in the solar wind; and the formation and structure of the lunar wake. Planetary topics include the lunar exosphere and its relationship to the composition of the lunar surface, the effects of electric fields on dust in the exosphere, internal structure of the Moon, and the lunar crustal magnetic field. This paper describes the expected contributions of ARTEMIS to these baseline scientific objectives.     

The Galactic Environment of the Sun: Interstellar Material Inside and Outside of the Heliosphere

Interstellar material (ISMa) is observed both inside and outside of the heliosphere. Relating these diverse sets of ISMa data provides a richer understanding of both the interstellar medium and the heliosphere. The galactic environment of the Sun is dominated by warm, low-density, partially ionized interstellar material consisting of atoms and dust grains. The properties of the heliosphere are dependent on the pressure, composition, radiation field, ionization, and magnetic field of ambient ISMa. The very low-density interior of the Local Bubble, combined with an expanding superbubble shell associated with star formation in the Scorpius-Centaurus Association, dominate the properties of the local interstellar medium (LISM). Once the heliosphere boundaries and interaction mechanisms are understood, interstellar gas, dust, pickup ions, and anomalous cosmic rays inside of the heliosphere can be directly compared to ISMa outside of the heliosphere. Our understanding of ISMa at the Sun is further enriched when the circumheliospheric interstellar material is compared to observations of other nearby ISMa and the overall context of our galactic environment. The IBEX mission will map the interaction region between the heliosphere and ISMa, and improve the accuracy of comparisons between ISMa inside and outside the heliosphere.     

Spiral descent of an unmanned aerial vehicle

An intensive unsteady spiral descent of an unmanned aerial vehicle with an approach to target (object) at the design altitude and specified minimal flight speed is considered. The decisive equations describing the motion of the FV center-of-mass are solved by time intervals. The influence of controlling parameters on the spiral radius, the maneuver speed and time is studied.     

Calculation of the thermostressed state of a turbine nozzle vane

We present a technique and results of calculating the cooling air pressure and flowrate in the turbine nozzle deflector vane duct, coefficients of heat transfer through air and from gas taking into account the influence of an air film heated in the perforation holes as well as temperature and thermal stresses in the vane elements and its thermal barrier coating in the GTE takeoff operational conditions. The effect of oval grooves in the coating behind the holes in the gas flow downstream direction and possible cracking of material on the thermal stress distribution in metal is considered.     

Mathematical modeling and experimental investigations of oxygen-methane fuel combustion at coaxial-jet supply into the combustion chamber of liquid-propellant rocket engine

The numerical results are presented for the case of coaxial-jet supply at the different ratio of mass component velocities at the combustion chamber inlet with the constant and variable relationship of oxygen-methane components. The experimental investigations of coaxial-jet mixing elements as part of the model setup chamber operating on corrosive producer gas and gaseous methane were carried out. A qualitative pattern of the $ overline {rho u} $ overline {rho u} parameter influence on the chamber economic feasibility was obtained: as $ overline {rho u} $ overline {rho u} decreases, the combustion efficiency coefficient grows.     

Ion-marking aerodynamic angle and airspeed sensor with logometric informative signals and interpolation processing scheme

We reveal a functional diagram, design features of a receiver electrode system, a principle of forming primary informative signals, a technique for synthesizing angular characteristics and estimating indicated errors, channel realization and algorithms of forming output signals of an ionmarking aerodynamic angle and airspeed sensor with logometric informative signals and interpolation processing scheme.     

Magnetic Turbulence in the Geospace Environment

Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere, and the interaction region between the magnetosphere and the solar wind. Recent spacecraft observations of magnetic turbulence in the ion foreshock, in the magnetosheath, in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere are reviewed. It is found that: 1. A large share of magnetic turbulence in the geospace environment is generated locally, as due for instance to the reflected ion beams in the ion foreshock, to temperature anisotropy in the magnetosheath and the polar cusp regions, to velocity shear in the magnetosheath and magnetotail, and to magnetic reconnection at the magnetopause and in the magnetotail. 2. Spectral indices close to the Kolmogorov value can be recovered for low frequency turbulence when long enough intervals at relatively constant flow speed are analyzed in the magnetotail, or when fluctuations in the magnetosheath are considered far downstream from the bow shock. 3. For high frequency turbulence, a spectral index α?2.3 or larger is observed in most geospace regions, in agreement with what is observed in the solar wind. 4. More studies are needed to gain an understanding of turbulence dissipation in the geospace environment, also keeping in mind that the strong temperature anisotropies which are observed show that wave particle interactions can be a source of wave emission rather than of turbulence dissipation. 5. Several spacecraft observations show the existence of vortices in the magnetosheath, on the magnetopause, in the magnetotail, and in the ionosphere, so that they may have a primary role in the turbulent injection and evolution. The influence of such a turbulence on the plasma transport, dynamics, and energization will be described, also using the results of numerical simulations.     

Gasdynamics of the solar wind interaction with the interstellar medium

A survey of the present-day situation in gasdynamical models of solar wind interaction with the local interstellar medium is presented. A role of these models in interpreting a number of observed physical phenomena is investigated. Experimental data and possible observations are considered from the viewpoint of their interpretation on the basis of theoretical models. Our attention is concentrated on the main limitations of the gasdynamical models, in particular, two-shocks model developed by Baranovet al. (1981, 1982).