Lafleur, T.Takahashi, K.Charles, C.Boswell, R. W.2015-12-072015-12-071070-664Xhttp://hdl.handle.net/1885/17050It is shown analytically that the thrust from a simple plasma thruster (in the absence of a magnetic field) is given by the maximum upstream electron pressure, even if the plasma diverges downstream. Direct thrust measurements of a thruster are then performed using a pendulum thrust balance and a laser displacement sensor. A maximum thrust of about 2 mN is obtained at 700 W for a thruster length of 17.5 cm and a flow rate of 0.9 mg s1, while a larger thrust of 4 mN is obtained at a similar power for a length of 9.5 cm and a flow rate of 1.65 mg s1. The measured thrusts are in good agreement with the maximum upstream electron pressure found from measurements of the plasma parameters and in fair agreement with a simple global approach used to model the thruster.Dr. K. Takahashi would like to thank the Faculty of Engineering at Iwate University (sabbatical year), the TEPCO Research Foundation in Japan, the MEXT in Japan (Grant-in-Aid for Young Scientists A 22684031), and the SP3 laboratory (Australian Research Council Discovery Grant No. DP 1096653) for financial support.4 pages©2011 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Physics of Plasmas and may be found at http://doi.org/10.1063/1.3610570 http://publishing.aip.org/authors/copyright-reuse http://www.sherpa.ac.uk/romeo/issn/1070-664X Author can archive publisher's version/PDF (Sherpa/Romeo as of 7/12/2015).thrustplasma thrustermaximum upstream electron pressureplasma diverges downstreampendulum thrust balancelaser displacement sensor2 mN700 W17.5 cm0.9 mg s1201110.1063/1.36105702015-12-08