Development and Testing of Electric Propulsion Systems at TU Dresden

Bock, Daniel; Drobny, Christian; Laufer, Philipp; Kößling, Matthias

doi:10.2514/6.2016-4848

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…We use the attocube FPS laser interferometer with superior resolution and drift characteristics which results in sub nano-Newton thrust resolutions and very low drifts which makes it one of the best thrust balances available today 15 . The torsion balance is mounted inside a large vacuum chamber (1.5 m length and 0.9 m diameter) which sits on top of a Newport optical table to damp it from outside vibrations (see Fig.…”

Section: B Torsion Balance Setup In Vacuum Chambermentioning

confidence: 99%

Direct Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects

Fiedler¹

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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The EMDrive has been proposed as a revolutionary propellantless thruster using a resonating microwave cavity. It is claimed to work on the difference in radiation pressure due to the geometry of its tapered resonance cavity. We attempted to replicate an EM Drive and tested it on both a knife-edge balance as well as on a torsion balance inside a vacuum chamber. After developing a numerical model to properly design our cavity for high efficiencies in close cooperation with the EM Drive's inventor, we built a breadboard out of copper with the possibility to tune the resonance frequency in order to match the resonance frequency of the magnetron which was attached on the side of the cavity. After measuring the Q-factor of our assembly, we connected the EMDrive to a commercial 700 W microwave magnetron. After a thermal mapping of the surfaces, we performed thrust measurements with a knife-edge balance as well as with a torsion balance in vacuum chamber. Our measurements reveal thrusts as expected from previous claims after carefully studying thermal and electromagnetic interferences. For the first time, measurements were also performed in high vacuum. Due to a low Q factor of <50, we observed thrusts of +/-20 µN. We identified the magnetic interaction of the power feeding lines going to and from the liquid metal contacts as the most important possible side-effect that is not fully characterized yet. Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far. Nevertheless, we do observe thrusts close to the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Nomenclature c = speed of light = 3×10 8 m/s f = frequency F = force P = power

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Section: B Torsion Balance Setup In Vacuum Chambermentioning

confidence: 99%

Direct Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects

Fiedler¹

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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“…In fact, NASA has started experiments with devices like Shawyer's one and constantly has improved it. Besides, Chinese researchers have also obtained much higher forces [7] in their studies involving the engine and other groups also have developed research in the area, involving advances in technology of propulsion, in studies of microwave devices or thrusters and photonic propulsion [29–32], showing how important has been the study of such a subject nowadays. The phenomenon of breakage of wires in which elevated currents flow has not been theoretically explained for a long time.…”

Section: Theoretical Descriptionmentioning

confidence: 99%

On the anomalous forces in microwave cavity‐magnetron systems

Porcelli

Filho

2019

J. eng.

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“…Although comprising two insulating oxides, it exhibits high electronic conductivity at room temperature, is chemically inert, and its work function is extremely low. Two research groups working in electric propulsion measured extremely low-work-function values (0.76 eV [36] and 0.6 eV [37]), but the intrinsic work function should be higher (2.1 eV [38] and 2.4 eV [39]). Besides the work function, the final optical properties of the coated tether surface are also critical.…”

Section: Lwt Materials Selectionmentioning

confidence: 99%

Modeling and Performance of Electrodynamic Low-Work-Function Tethers with Photoemission Effects

Sánchez‐Arriaga

Chen

2018

Journal of Propulsion and Power

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A low-work-function tether is a long conductor coated with a low-work-function material that orbits around a planet with both the magnetic field and ionosphere. Depending on the work function W of the coating and the tether temperature T, the photoelectron emission can be relevant within the cathodic tether segment. Thus, this mechanism needs to be added to the thermionic emission considered in previous works. An emission model for low-work-function tethers, including a typical solar photon spectrum, a Fowler-DuBridge law for the photoelectron yield of the coating, and a Richardson-Dushman law for the thermionic emission, is presented, and used to organize the thermionic and photoelectric dominated regimes of low-work-function tethers within the W-T plane. For T ≈ 500 K and W ≈ 1.5 eV, the photoemission and thermionic emission can be of the same order and have similar efficiency as the electron collection. The emission model is combined with orbital-motion theory for all the plasma and emitted particles, and the longitudinal bias and current profiles throughout a low-work-function tether are determined for typical low-Earth-orbit environmental values. Results for the average current are presented. The study highlights the main electrical, mechanical, and optical properties that should be considered in the design of low-work-function tethers, and it briefly discusses some promising materials.

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Development and Testing of Electric Propulsion Systems at TU Dresden

Cited by 6 publications

References 7 publications

Direct Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects

Direct Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects

On the anomalous forces in microwave cavity‐magnetron systems

Modeling and Performance of Electrodynamic Low-Work-Function Tethers with Photoemission Effects

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