Microvacuum Arc Thruster Design for a Cubesat Class Satellite

This paper describes the University of Illinois 2-cube CubeSat (10 x 10 x 20 cm) designed for April 2003 launch. The Illinois Observing NanoSatellite (ION) includes a scientific mission to view the airglow layer of the atmosphere and a CMOS camera for space and Earth photography. ION will also be used as a test bed to demonstrate a number of technologies including an active 3-axis attitude control system, with a new propulsion system used for both attitude control as well as orbital maneuvers. The new vacuum arc thruster (VAT) propulsion system produces ion velocities of up to 30,000 m/s, driven mostly by local pressure gradients. A 12 V inductive energy storage circuit is used to provide the initial breakdown and to sustain the plasma. Four thruster heads can be controlled individually to produce arc pulses with adjustable pulse width and repetition rate. Size and mass have been driven by the CubeSat requirements and amount to 4 x 4 x 4 cm and 150 g, respectively. Thrust to power ratios are expected to be ≈10μN/W. The individual impulse will be close to 1μN-s/pulse. Challenges to the design and integration of the VAT into a CubeSat size satellite are presented. On board diagnostics and methods used to verify operation of the VAT are discussed

Vacuum arc plasma thrusters with inductive energy storage driver

An apparatus for producing a vacuum arc plasma source device using a low mass, compact inductive energy storage circuit powered by a low voltage DC supply acts as a vacuum arc plasma thruster. An inductor is charged through a switch, subsequently the switch is opened and a voltage spike of Ldi/dt is produced initiating plasma across a resistive path separating anode and cathode. The plasma is subsequently maintained by energy stored in the inductor. Plasma is produced from cathode material, which allows for any electrically conductive material to be used. A planar structure, a tubular structure, and a coaxial structure allow for consumption of cathode material feed and thereby long lifetime of the thruster for long durations of time

Innovative Vacuum Arc Thruster for CubeSat Constellations

Abstract: The University of the Federal Armed Forces (UniBwM) is currently developing an innovative electric propulsion system for small satellites with extremly low space, mass and power budget. Satellites with these characteristics were built by the JustusMaximilians-Universität Würzburg (JMUW) within the international CubeSat project. the Bavarian government UniBwM and JMUW are working together to equip the new pico satellite UWE-4 (Universität Würzburg Experimentalsatellit 4) with a sufficient propulsion system for fine positioning and attitude control. JMUW is responsible for the development of the satellite and the integration of the propulsion system which is currently under development at UniBwM based on the so called Vacuum Arc Thruster. To demonstrate the positioning ability of the system the mission of UWE-4 is to chase another CubeSat and to hold its relative position. Together with the strict restrictions of the CubeSat this gives some serious challenges to be solved

Magnetically enhanced vacuum arc thruster

A hydrodynamic model of the vacuum arc thruster and its plume is described. Primarily an effect of the magnetic field on the plume expansion and plasma generation is considered. Two particular examples are investigated, namely the magnetically enhanced co-axial vacuum arc thruster (MVAT) and the vacuum arc thruster with ring electrodes (RVAT). It is found that the magnetic field significantly decreases the plasma plume radial expansion under typical conditions. Predicted plasma density profiles in the plume of the MVAT are compared with experimental profiles, and generally a good agreement is found. In the case of the RVAT the influence of the magnetic field leads to plasma jet deceleration, which explains the non-monotonic dependence of the ion current density, on an axial magnetic field observed experimentally.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49190/2/psst5_4_004.pd

Space micropropulsion systems for Cubesats and small satellites: From proximate targets to furthermost frontiers

Rapid evolution of miniaturized, automatic, robotized, function-centered devices has redefined space technology, bringing closer the realization of most ambitious interplanetary missions and intense near-Earth space exploration. Small unmanned satellites and probes are now being launched in hundreds at a time, resurrecting a dream of satellite constellations, i.e., wide, all-covering networks of small satellites capable of forming universal multifunctional, intelligent platforms for global communication, navigation, ubiquitous data mining, Earth observation, and many other functions, which was once doomed by the extraordinary cost of such systems. The ingression of novel nanostructured materials provided a solid base that enabled the advancement of these affordable systems in aspects of power, instrumentation, and communication. However, absence of efficient and reliable thrust systems with the capacity to support precise maneuvering of small satellites and CubeSats over long periods of deployment remains a real stumbling block both for the deployment of large satellite systems and for further exploration of deep space using a new generation of spacecraft. The last few years have seen tremendous global efforts to develop various miniaturized space thrusters, with great success stories. Yet, there are critical challenges that still face the space technology. These have been outlined at an inaugural International Workshop on Micropropulsion and Cubesats, MPCS-2017, a joint effort between Plasma Sources and Application Centre/Space Propulsion Centre (Singapore) and the Micropropulsion and Nanotechnology Lab, the G. Washington University (USA) devoted to miniaturized space propulsion systems, and hosted by CNR-Nanotec - P.Las.M.I. lab in Bari, Italy. This focused review aims to highlight the most promising developments reported at MPCS-2017 by leading world-reputed experts in miniaturized space propulsion systems. Recent advances in several major types of small thrusters including Hall thrusters, ion engines, helicon, and vacuum arc devices are presented, and trends and perspectives are outlined.This work was supported in part by the following funds and organizations: OSTIn-SRP/EDB through National Research Foundation and in part by MoE AcRF (Rp6/16 Xs), Singapore; National Natural Science Foundation of China (Grant Nos. 51777045 and 51477035); National Technical Basic Scientific Research of China, Grant No. JSZL2016203c006; NASA DC Space Grant Consortium; Grant-in-Aid for Scientific Research under Grant S: 21226019 and Grant B: 17H02295 through the Japan Society for the Promotion of Science, and by NIFS budget code NIFS17KLER063, and KAKENHI grant: Grant-in-Aid for Scientific Research (S), No. JP16H06370; S.S. thanks late Professor K. Toki, late Dr. K. P. Shamrai, Dr. Kuwahara, and the HEAT project members for their contribution Y.R. acknowledges the support from the US DOE under Contract No. DE-AC02-09CH11466; I.L. acknowledges the support from the School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology; special thanks to L. Xu, M. Lim, S. Huang, and the entire PSAC/SPCS for their help

Інформаційна технологія для класифікації наукових текстів на основі методу модифікованої логістичної регресії

Об’єкт дослідження: процес класифікації наукових текстів та практичне використання технологій обробки природної мови в освітніх додатках, з метою підвищення ефективності освітнього процесу. Предмет дослідження: методи, моделі машинного навчання та обробки природньої мови у задачах класифікації наукових текстів. Мета магістерської роботи: вдосконалення та пришвидшення процесу класифікації текстів з допомогою моделі логістичної регресії, з метою застосування її у освітніх додатках для покращення освітнього процесу. Методи дослідження. Для створення рекомендаційного та навчального асистента були використані засоби та методи машинного навчання, теорії множин, лінейної алгебри й обробки природної мови. Наукова новизна полягає у тому, що вдосконалено та розширено можливості методу логістичної регресії на основі комбінування його з методом ранжування, що в результаті дозволило використати метод логістичної регресії для навчального асистенті. Практична цінність полягає у тому, що в результаті роботи, було створено прототип навчального асистента, що використовує скомбіновану з методом ранжування модель логістичної регресії для класифікації текстів. Використані методи та підходи у прототипі можуть застосовуватись як при розробці «інтелектуальних» навчальних систем, так й в практиці викладання дисциплін, пов’язаних з обробкою природної мови

Experimental Characterization of the Capacitively Coupled RF-Plasma Thruster

A novel design of a neutralizer-free plasma thruster is proposed. This setup features a capacitively coupled RF discharge for plasma generation combined with a magnetic nozzle configuration for acceleration. Characteristics of the plasma plume and ions flux are investigated with the help of emissive probes and retarding potential analyzers (RPA). Essential parameters of the thruster like ions energy, ions flux, utilization efficiencies, and thrust are estimated. The investigated system produces a beam of ions accelerated to an energy of 10 eV when operated at power levels of ~20 W and a mass flow of 1.2 mg/s. The ion energy coincides with the potential drop in the plasma plume indicating that the acceleration takes place due the formation of an ambipolar electric field in the expanding plasma. The design is compared to the data available of other similar thrusters

Investigations and New Physical Behaviour of Special DC-Plasma Generator Mettech "Axial III"

The use of plasma generators for thermal surface coating has grown enormously in the field of thermal insulation and wear resistant coatings, especially with regard to deposition of refractory oxide ceramic layers using powders such as aluminum oxide, alumina / titania, zirconia and chromium oxide. Nonetheless, innovative plasma sources are still being developed to provide more-efficient, tailor-made solutions due to their specific characteristics. A brief overview of the DC plasma generator Mettech “Axial III” are shown, which generator are allowed to use the central injection (advantage for suspension applications). In this paper first diagnostic results characterized the physical behaviour and special plasma symmetry, which can be described by three partial plasma jets. Thereby computer tomography (CT), high speed camera investigations coupled with time-adjusted current-voltage measurements, particle parameter detections and first resulting coatings are presented and discussed. The complete paper concludes with an outlook for future diagnostic measurements and possible future applications for this DC-plasma torch