Algorithm for calculating the problem of unilateral frictional contact with an increscent external load parameter

The subject of the study is the contact interaction of deformable elements of linear complementarity problem (LCP). To solve the linear complementarity problem, the Lemke method with the introduction of an increasing parameter of external loading is used. The proposed approach solves the degenerated matrix in a finite number of steps, while the dimensionality of the problem is limited to the area of contact. To solve the problem, the initial table of the Lemke method is generated using the contact matrix of stiffness and the contact load vector. The unknowns in the problem are mutual displacements and interaction forces of contacting pairs of points of deformable solids. The proposed approach makes it possible to evaluate the change in working schemes as the parameter of external load increases. The features of the proposed formulation of the problem are shown, the criteria for stopping the stepwise process of solving such problems are considered. Model examples for the proposed algorithm are given. The algorithm has shown its efficiency in application, including for complex model problems. Recommendations on the use of the proposed approach are given

High Power Electric Propulsion: MARS plus EUROPA – Already Beyond 2025!

It’s mid-term realization plus global strategic investments: the results of the European Russian DEMOCRITOS project (Horizon 2020) related to the MW class INPPS (International Nuclear Power and Propulsion System) flagship will be described. INPPS flagship includes high power electric thrusters cluster, supplied electric power by the nuclear reactor (successfully tested in Russia) and a solar power ring. Two INPPS versions were studied – the wide and arrow wing versions. Both versions have a futuristic design with standardized interfaces for several flagship subsystems. Especially the high payload mass of INPPS allows the transport of – for example – up to 12 t to JUPITER moon EUROPA and about 18 t to MARS – as a function of specific impulse of electric thrusters. INPPS flagship not only allows scientific, but especially commercial and communication payloads as well. This means industrial-scale production of space flight systems for robotic and human space exploration. International cooperation related to INPPS realization are necessary within an International High Power Space Transportation program to realize the DEMOCRITOS core, ground and space components until 2025. DEMOCRITOS project included partners from Europe, Russia and a Brazilian guest observer and received several inputs from NASA Cleveland and JAXA Tokyo

The interaction of a concentrated electron beam in a dense gas medium

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation into the ionization and acceleration regions shift in a Hall thruster channel

Location of the ionization and acceleration regions determines erosion belt location and thruster’s maximum throughput consequently. For Hall thrusters with wide throttle ratio the location of the ionization and acceleration regions in each operating mode could vary significantly, which makes it difficult to provide necessary throughput for multi-mode operation. In this article, the shift of the ionization and acceleration region location caused by the change of operating mode is studied with the help of numerical method. Numerical investigation was conducted with 1D3V hybrid-PIC simulations. According to the results, the ionization and acceleration regions could move upstream significantly with gas flow rate increase and magnetic field decrease. In addition, it was proved that an increase in the magnetic field gradient shifts the ionization and acceleration region location outside of the channel significantly. The trends obtained in numerical simulations were experimentally testified. The acceleration region trend validation was carried out with electrical probe measurements on a 1.5 kW laboratory Hall thruster. The ionization region shift was validated with the shift of the maximum light intensity of the xenon inside the channel of a 2.3 kW laboratory Hall thruster. Moreover, experimental investigations indicate that the ionization and acceleration regions could move significantly when oscillation mode changes

Development of ion thruster IT-500

A high-power ion thruster IT-500 was designed, manufactured and tested at Keldysh Research Center within a transport-power module project. This module is being designed to perform near-Earth space and interplanetary transport missions. In its nominal operation mode, IT-500 provides thrust in the range from 375 to 750 mN at specific impulse of 70 000 m/s and thrust efficiency of 0.75. Due to a high cost of the experimental testing of a large thruster, the emphasis was placed on the numerical optimization of the thruster design. The thruster completed performance tests and a 300 h wear test. The output characteristics of the thruster, obtained during the tests, confirmed the correctness of the provisional numerical optimization. IT-500 design, performance, and validation of the design approaches are discussed in this paper

INPPS Flagship: Cluster of Electric Thrusters

This paper describes the results of the European-Russian DEMOCRITOS and MEGAHIT projects related to the electric thrusters on board the International Nuclear Power and Propulsion System (INPPS) flagship. INPPS flagship is a high power space transportation hybrid tug (power supply primary by nuclear power, by auxiliary solar power ring and chemical propulsion due to subsystems transport for assembly at high Earth orbit above 800 km) for Mars, Europa, Moon and asteroid exploration flights. In dependence from the actual exploration mission, mission phases, trajectory, and preferred international high power electric thrusters (about 20 - 50 kW) with different specific impulse, the results will be discussed in detail - also as a function of the transportable payload mass. Because of the 1 MWe nuclear reactor (successful ground based test confirmed by Russia in 2018) as the power supply for INPPS a cluster of about 15 or more electric thrusters were studied in the DEMOCRITOS project for MARS and EUROPA INPPS flagships. Issues related to power processing units for the electric thrusters were identified and will be discussed. In addition, low power (kW) electric thrusters for an INPPS flagship co-flying small inspection satellite are sketched too. Insofar the presentation is directly highlighting aspects of disruptive electric propulsion subsystems, within the INPPS space system and applied to visionary Mars (including non-human and human) and Europa exploration and space transport tug flights