100 research outputs found
Optical Measurements of High-Density Helicon Plasma by Using a High-Speed Camera and Monochromators * )
Electric propulsion is an established high-efficiency method in deep space explorers. However, most of the applied methods feature electrodes in direct contact with the plasma, thus its lifetime is limited by the electrodes' erosion. We developed electrodeless electric propulsion systems in order to overcome this problem, and performed optical measurements to estimate the high-density helicon plasma performance of the systems. The electron and neutral particle density profiles were measured by a high-speed camera, and the velocity of the singly-charged Ar ions was determined by a high-resolution monochromator. Additionally, a preliminary experiment of a spectroscopic method using an intensity ratio based on a collisional radiative model with a CCD monochromator was performed. The plasma parameters were in good agreement with the results obtained by an electrostatic probe, and the non-invasive optical measurements presented here can constitute an effective tool for evaluating an electric propulsion system
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
Large-volume, helicon-plasma source for simulation experiments of space plasmas
12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France)A large-volume, helicon-plasma source (73.8 cm in diameter and 486 cm in axial length) has been developed to be used to investigate various wave phenomena observed in space plasmas, and its characteristics have been investigated. The discharge antenna used is a flat spiral type installed just outside the quartz-glass window at one end of the vacuum vessel, where the background magnetic field (B-field) is nonuniform. Antennae of two different sizes are used: 23 cm in diameter with 6 spiral turns and 43 cm in diameter with 4 spiral turns (the number of spiral turns is smaller for the latter so as not to increase the antenna inductance significantly). The uniform B-field in the central plasma region can be varied up to 2 kG. The plasma density after the density jump for Ar and He plasmas can exceed 10 12 cm-3 with approximately 600 W of the injected rf power at 7 MHz. The reason for this excellent discharge efficiency is discussed, considering the power balance between input and loss. It has been found that the radial density profile can be varied rather easily by applying the following two means: 1) by changing the B-field configurations near the antenna by adjusting the field strength of the auxiliary coil installed near the antenna and 2) by changing the antenna radiation-field patterns by using the different rf feeding points on the antenna. By changing the magnetic field configuration near the antenna, the threshold power and the degree of the density change in a density jump can be varied. The electron density reaches the maximum away from the antenna; then decays weakly along the axial direction
Initial Trial of Plasma Mass Separation by Crossed Electric and Magnetic Fields
Using segmented concentric rings to produce a radial electric field, an initial trial experiment on ion mass separation in a magnetized plasma with low collisionality has been successfully carried out. With the increase in electric field or the decrease in magnetic field, the azimuthal flow velocity in the Xe plasma saturated and then it decayed due to the unconfined condition. On the other hand, the Ar plasma, whose mass is lighter than the Xe one, did not show this behavior in this operational region. These results are consistent with a particle orbit analysis and a simple calculation of the balances of forces
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