Martin Tajmar

Martin Tajmar
Technische Universität Dresden | TUD · Institut für Luft- und Raumfahrttechnik

Prof. Dr.

About

334
Publications
250,287
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3,056
Citations
Citations since 2017
118 Research Items
1648 Citations
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20172018201920202021202220230100200300400

Publications

Publications (334)
Article
Full-text available
Diagnostics with force probes in plumes of electric propulsion systems for spacecraft (thrusters) are presented. This contribution focuses on showing example measurements with force probes for the most common gridless ion thruster types. The gridless thrusters are investigated at typical operation modes with a force probe at fixed or variable posit...
Preprint
Full-text available
Direct numerical simulations of non-premixed fuel-rich methane-oxygen flames at 20 bar are conducted to investigate the turbulent mixing burning of gaseous propellants in rocket engines. The reacting flow is simulated using the EBI-DNS solver, within the OpenFOAM frame. The transport of species is resolved with finite rate chemistry, using a comple...
Article
Full-text available
The usage of direct numerical simulations for research of turbulent combustion for space propulsion applications is explored. With this goal in mind, the combustion near injection of a fuel-rich methane-oxygen flame at 20 bar is simulated using a massively parallelized solver. The statistical properties of the relevant physical fields are examined...
Article
Full-text available
Hall-effect thrusters (HETs) are among the most commonly used propulsion systems for attitude and orbit control of satellites. As an arrangement in a cluster or individually, equipped with a mechanical suspension, thrust in all three spatial directions can be generated, but requires additional mechanisms and components. Therefore, the Technische Un...
Article
Full-text available
This study explores the possibility of miniaturizing magnetoplasmadynamic thrusters (MPDTs) to significantly lower power and discharge current levels compared to most conventional MPDTs. A design alternative for MPDTs using a discharge channel with a rectangular cross-section is presented that enables the implementation of strong external magnetic...
Article
Full-text available
The low‐work function material [Ca24Al28O64]4+(4e−) – named as C12A7:e‐ or electride – is a promising candidate to replace established materials such as BaO‐W or LaB6 electron emitters because of its good reported electron emission in plasma environments and decent chemical inertness. However, it has poor thermal conductivity and low mechanical beh...
Article
Full-text available
This contribution describes the investigation of flow channels which are designed to be directly integrated into an aerospike engine by means of additive manufacturing with laser powder bed fusion (LPBF). During the experimental testing of a previous aerospike engine in 2019, it was observed that high surface roughness of such additively manufactur...
Article
Full-text available
This work aims to provide support for the design of reliable DNSs for statistically planar flames. Improved simulation design strategies are developed. Therefore, design criteria for the simulative domain are discussed. The gained mathematical relations for all of the relevant physical quantities were channelled into a deterministic calculation str...
Conference Paper
Full-text available
Leading space agencies and companies identified the utilization of local resources as foundation for the continuous long-term exploration of the solar system within the Global Exploration Roadmap. In-Situ Resource Utilization (ISRU) will be one of the key technologies for sustainable space exploration and habitation missions to Moon, Mars and beyon...
Conference Paper
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The fast-paced growth of the space sector brings in new challenges especially with upcoming complex missions combining multi-orbit deliveries and/or on-orbit servicing such as Active Debris Removal (ADR). Europe has taken up the challenges and is working on extending its launchers portfolio and capabilities. In this framework, a new add-on, the kic...
Article
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This paper analyses the synergy between two innovative technologies: green propellants and electric pump feeding, for a 500 N engine thrust range. The novel approach is then compared to the legacy configuration, i.e., an MMH/NTO pressure fed system. First, a discussion of the benefits and challenges of the different technologies is presented. Subse...
Article
Full-text available
Direct numerical simulations of a turbulent premixed stoichiometric methane-oxygen flame were conducted. The chosen combustion pressure was 20 bar, to resemble conditions encountered in modern rocket combustors. The chemical reactions followed finite rate detailed mechanism integrated into the EBI-DNS solver within the OpenFOAM framework. Flame...
Article
Full-text available
With regard to the space field, the number of the sensors has grown for a middle-sized spacecraft from more than 500 at the beginning of the twenty-first century [1] to several thousands for nowadays applications. Meanwhile, Reusable Launch Vehicles (RLVs) moved their steps from demonstrators to commercial working systems. As a result, Health Monit...
Article
Full-text available
Here, we present a novel torsion balance with a torsional spring that can reach a resolution in the nano-Newton range while allowing for a total experimental weight of 2 kg. The balance uses an off-the-shelf electromagnetic actuator, which was calibrated. The oscillation of the balance is damped using an adaptable eddy-current brake to fine-tune th...
Conference Paper
Full-text available
A hollow cathode is being developed as an active electron emitter for an electrodynamic tether demonstrater. For such an experiment, low emission currents in the range of a few hundred milliamps with a low overall power consumption of a few watts are required. Such requirements-especially the low current range-are difficult to meet for most state-o...
Conference Paper
Full-text available
In this contribution, the design process and the preparation of a hot-fire test campaign of an additively manufactured, annular aerospike engine is presented. The development of the engine, which is manufactured from the nickel-base superalloy INCONEL® 718 using laser powder bed fusion, is part of the cooperation project CFDµSAT between the Technis...
Article
Full-text available
A volume-averaged hollow cathode plasma model is presented that serves as a preliminary design tool for orificed hollow cathodes. The plasma discharge volume is subdivided into two computational domains with separate sub-models that are used to determine the emitter and orifice region plasma parameters. The plasma model is coupled with a lumped nod...
Article
Full-text available
The development and experimental investigation of two low-power electric propulsion concepts using compact heaterless C12A7 electride (C12A7:e-) hollow cathodes is presented. The first concept represents an electrothermal thruster, in which a cathode discharge is used to heat a gas that is subsequently accelerated in a nozzle-shaped anode. The seco...
Conference Paper
Full-text available
Within the frame of the ESA funded ASPIRER project , an additively manufactured aerospike bread-board engine, using kerosene and hydrogen perox-ide as propellants, is developed and tested. This contribution summarizes the fluid simulation activities carried out during the project with focus on the hydraulic design of the cooling channels and the ae...
Conference Paper
Full-text available
Additive Manufacturing (AM) methods drastically simplify or even enable the fabrication of complex structures such as aerospike nozzles while minimising the number of individual parts. The general advantages of additively manufactured ceramic components lie in their low density combined with high strength as well as chemical and thermal resistance....
Conference Paper
In this contribution, an overview is given about the MACARONIS project in which a cold-gas thruster system is developed, aiming for an in-orbit demonstration of a ceramic Additively Manufactured (AM) aerospike nozzle made of alumina (Al2O3). The advantages of AM ceramic components lie for the present application in their low density combined with h...
Conference Paper
Additive Manufacturing (AM) processes offer geometrical freedom to design complex shaped parts that cannot be manufactured with conventional processes. This leads to new applications including aerospace propulsion systems where the Ni-superalloy based material has to withstand high operating temperatures. In this contribution, the influence of heat...
Article
Full-text available
Does a supercurrent drag space-time or generate a gravitational field that can be measured in a laboratory environment? A number of theories suggest that space-time itself could be modeled as a superfluid, so a current of Cooper-pairs might couple to its surroundings differently compared to non-quantum matter. On the other hand, experiments appeare...
Chapter
„Science-Fiction wie Star Trek ist nicht nur Unterhaltung, sondern erfüllt auch einen ernsten Zweck: Sie erweitert die menschliche Vorstellungskraft“, schrieb Stephen Hawking (Abb. 16.1) im Vorwort des Buches „Die Physik von Star Trek“ des amerikanischen Physikers Lawrence M. Krauss. Hawking und Krauss sind bei Weitem nicht die einzigen Wissenschaf...
Article
Full-text available
As advanced nozzles may offer alternative solutions to conventional nozzles for the future class of reusable launch vehicles, a critical aspect is to tailor these novel technologies to current recovery strategies, more specifically to vertical landing sustained by retro-propulsion. Researchers at Technische Universität Dresden have developed a dedi...
Article
Full-text available
A turbulent methane-oxygen diffusion flame is studied using a direct numerical simulation setup. The operating regime and turbulence characteristics are chosen to resemble those of a modern methane rocket combustor. Local flame characteristics and dimensionless numbers are defined, evaluated, and their relationship with the turbulent kinetic energy...
Conference Paper
Full-text available
Concurrent engineering is an approach to the development of complex systems that is char- acterised by direct communication between the disciplines involved. Instead of processing the individual disciplines one after the other, as in sequential design, or processing via a single contact person, as in centralised design, all systems work simultaneou...
Conference Paper
The field of access to space is wide and complex, and it involves several disciplines and areas of expertise such as propulsion physics, software development, experimental studies, numerical simulations, thermodynamics, missionisation, etc. A gap in the training of young European researchers at doctoral level has been identified in this field, as n...
Article
In Low Earth Orbit, it is possible to use the ambient plasma and the geomagnetic field to exchange momentum with the Earth's magnetosphere without using propellant. A device that allows an efficient momentum exchange is the electrodynamic tether (EDT), a long conductor attached to the satellite. EDT technology has been demonstrated in several past...
Article
Propellantless propulsion concepts based on electromagnetic waves like the EMDrive are claimed to be far superior with respect to the state of spacecraft propulsion systems. Such devices consist of enclosed cavities with different geometric shapes that are injected with electromagnetic waves, producing unidirectional thrust without expelling propel...
Article
Full-text available
The generation of periodic synthetic turbulence through superposition of Fourier modes is investigated. The introduction of directional biases and mismatches in the second-order statistics associated to the enforcement of periodicity is analyzed and quantified. Two strategies for mitigation of these disparities are proposed. The suggested approache...
Conference Paper
Full-text available
Propellantless propulsion concepts based on electromagnetic waves like the EMDrive are claimed to be far superior with respect to the state of spacecraft propulsion systems. Such devices consist of enclosed cavities with different geometric shapes that are injected with electromagnetic waves, producing unidirectional thrust without expelling propel...
Conference Paper
Full-text available
The bell-shaped nozzle deserves its role in modern rocket science as key technology that contributed to making space accessible. Nevertheless, recent achievements in the main stage recovery of the current class of Reusable Launch Vehicles (RLVs) force the community to question the effectiveness of bell nozzle design for this scenario. Indeed, bell...
Conference Paper
The growing demand for cheaper space access calls for a more economically and environmentally sustainable approach for launchers. Concurrently, the shift to smaller satellites and the rise of constellations necessitate launchers capable of precise multi-payload/multi-orbit injection. ASCenSIon (Advancing Space Access Capabilities-Reusability and Mu...
Conference Paper
Full-text available
Within the framework of the ESA funded ASPIRER project, an additively manufactured aerospike breadboard thrust chamber using kerosene and hydrogen peroxide as propellants is developed and tested. This contribution summarizes the design and test planning activities carried out during the project. In this regard, the overall system design is discusse...
Patent
Die Erfindung bezieht sich auf das Gebiet der Messverfahren und der Umwelttechnik und betrifft ein Verfahren zur thermo-optischen Analyse von Schnee- und Eisschichtungen sowie ein thermo-optisches Analysesystem. Aufgabe der Erfindung ist es, ein Verfahren zur Analyse von Schnee- und Eisschichtungen und ein Analysesystem bereitzustellen, mit dem ein...
Article
Full-text available
The EMDrive is a proposed propellantless propulsion concept claiming to be many orders of magnitude more efficient than classical radiation pressure forces. It is based on microwaves, which are injected into a closed tapered cavity, producing a unidirectional thrust with values of at least 1 mN/kW. This was met with high scepticism going against ba...
Conference Paper
Journal Lessons Learned, TU Dresden, ISSN: 2749-1293 (Print); 2749-1307 (Online) Concurrent engineering is an approach to the development of complex systems that is characterised by direct communication between the disciplines involved. Learning this interaction and understanding what information needs to be communicated between disciplines are amo...
Conference Paper
Full-text available
Facing the ever-growing commercialisation of space, particularly within low earth orbit, the academic space sector has reached a pivotal point that will define its role in the upcoming decades. At the same time, space exploration has reached its biggest momentum since the Apollo era. In the Global Exploration Roadmap, the leading space fairing nati...
Article
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A correction to this paper has been published: https://doi.org/10.1007/s12567-021-00372-6
Article
Full-text available
Two electric propulsion concepts have been developed at Technische Universität Dresden as spin-off devices of regular hollow cathodes and initial testing has been conducted. Both devices represent millinewton thrusters that take advantage of thermionic electron emission using the low work function materials C12A7, LaB6, and thoriated tungsten in di...
Patent
[eng] The invention involves a protective film for frequency-selective shielding of electromagnetic radiation. The protective film comprises a thin film (1) formed with carbon nanotubes. In the thin film (1) or on at least one surface of the thin film (1), a structuring is formed in such a way that electromagnetic radiation impinging on the thin fi...
Patent
Die Sensorvorrichtung zum Bestimmen der relativen Feuchtigkeit in einem Gasvolumen umfasst einen Sensorträger (1) und ein Kompositmaterial (2), das auf einer Oberfläche des Sensorträgers (1) angeordnet ist. Dabei ist das Kompositmaterial (2) mit einem Epoxidharz, einem Silikon oder einem sulfonierten, perfluorierten Polymer und Kohlenstoffnanoröhre...
Article
Full-text available
This work presents experiments about the transmission of electrons with an energy of around 15 keV with beam currents up to 20 µA through macroscopic glass capillaries. A systematic study was conducted to experimentally investigate the transmission of electrons through borosilicate glass capillaries with curve angles of 90°, 180°, 270° and 360° for...
Article
Full-text available
Since modern propulsion systems are insufficient for large-scale space exploration, a breakthrough in propulsion physics is required. Amongst different concepts, the EMDrive is a proposed device claiming to be more efficient in converting energy into propulsive forces than classical photon momentum exchange. It is based on a microwave resonator ins...
Conference Paper
Full-text available
A miniaturized hollow cathode is being developed and tested in the advanced propulsion laboratory of the Institute of Aerospace Engineering at the Technische Universität Dresden. The cathode features the use of C12A7 electride as emitter material. Although most recent measurements of work functions do indicate a value in the order of 2.4 eV to 2.8...
Conference Paper
Full-text available
Concepts for propellantless space propulsion are carefully investigated using high-precision balances in the framework of the SpaceDrive Project. The Mach-Effect-Thruster, an original design from Woodward that relies on the particular vibration of an asymmetric, piezoelectric stack actuator to produce thrust, is one concept that was extensively tes...
Conference Paper
Full-text available
Since modern propulsion systems are insufficient for large-scale space exploration, a breakthrough in propulsion physics is required. Amongst different concepts, the EMDrive is a proposed device claiming to be more efficient in converting energy into propulsive forces than classical photon momentum exchange. It is based on a microwave resonator ins...
Conference Paper
Full-text available
The EMDrive is a proposed propellantless propulsion concept claiming to be many orders of magnitude more efficient than classical radiation pressure forces. It is based on microwaves, which are injected into a closed tapered cavity, producing a unidirectional thrust with values of at least one mN/kW. This was met with high scepticism going against...
Conference Paper
Full-text available
In this contribution, numerical analyses are performed to predict the asymmetrical pressure distributions on the surface of linear, truncated aerospike nozzles due to aerodynamic thrust vectoring. Furthermore, the occurring flow features such as separation shocks and the penetration height of the developing Mach disk within the primary flow field i...
Conference Paper
Full-text available
Linear and annular aerospike nozzles with thrust vector control through secondary fluid injection (SITVC) are investigated at Technische Universität Dresden. For that purpose, a cold-flow test bench with a six-degree of freedom (6-DOF) force balance has been set up and mounted into a vacuum chamber for higher nozzle pressure ratios. In this contrib...
Article
Full-text available
State-of-the-art electrodynamic tethers reach a steady electric current by using a bare segment to capture electrons passively from the ambient plasma (anodic contact) and an active electron emitter or a tether segment coated with a low-work-function material (cathodic contact) to emit electrons back and close the electrical circuit. This work prop...
Article
Full-text available
Successful interstellar venture depends on the development of propellantless propulsion with a thrust-to-power ratio much greater than a photon rocket and without the limitations of solar sails. Claims of μN thrust for Woodward's MEGA Drive, along with predicted mass fluctuations as a consequence of the Mach-Effect have initiated a few decades of t...
Article
An inertial electrostatic confinement (IEC) fusion device accelerates ions, such as deuterium (D) or tritium (T), to produce nuclear fusion and generate neutrons. The IEC's straightforward configuration consists of a concentric spherical transparent cathode at a negative bias surrounded by a grounded spherical anode. The effects of cathode properti...
Preprint
Full-text available
This work presents experiments about the transmission of electrons with an energy of around 15 keV with beam currents up to 20 µA through macroscopic glass capillaries. A systematic study was conducted to experimentally investigate the transmission of electrons through borosilicate glass capillaries with curve angles of 90°, 180°, 270° and 360° for...
Article
The calcium aluminate electride [ Ca 24 Al 28 O 64 ] 4 + ( e − ) 4 (C12A7: e −) is chemically and thermally stable in ambient atmosphere, offers strong electron donating capabilities and exhibits an intrinsic work function of 2.4 eV. Thus, it is an attractive material for electron emitter and low work function applications. For an implementation in...
Preprint
Special relativity predicts a very small influence of temperature on mass of around ${\Delta}m/m{\approx}10^{-14}$. More than 100 years ago, experiments were performed that revealed a limit of $<10^{-8}$ for changes of a few degree at room temperature. A similar limit was obtained with a magnetic suspension balance at cryogenic temperatures. Recent...
Article
Full-text available
This paper presents two technology experiments – the plasma brake for deorbiting and the electric solar wind sail for interplanetary propulsion – on board the ESTCube-2 and FORESAIL-1 satellites. Since both technologies employ the Coulomb interaction between a charged tether and a plasma flow, they are commonly referred to as Coulomb drag propulsio...
Article
Full-text available
Special relativity predicts a very small influence of temperature on mass of around Δmm≈10-14. More than 100 years ago, experiments were performed that revealed a limit of <10⁻⁸ for changes of a few degree at room temperature. A similar limit was obtained with a magnetic suspension balance at cryogenic temperatures. Recently, some measurements clai...
Article
Full-text available
Kaluza was the first to realize that the four-dimensional gravitational field of general relativity and the classical electromagnetic field behave as if they were components of a five-dimensional gravitational field. We present a novel experimental test of the macroscopic classical interpretation of the Kaluza fifth dimension. Our experiment design...
Conference Paper
Full-text available
The trend towards smaller satellites and mega-constellations has enormously changed the space sector and its uti-lisation in the last decades, allowing new players to enter the market and to introduce stringent requirements to enable a variety of novel applications. Alongside, also the launcher market is undergoing a transformation epoch: the devel...
Conference Paper
Full-text available
In this contribution, the results of a hot fire test campaign using a 500 N truncated annular aerospike engine are discussed as well as the underlying investigations. The designed aerospike serves as a proof of concept for the additive manufacturing of such an engine by the means of laser powder bed fusion (LPBF). Manufacturing, thermal treatment a...
Preprint
Full-text available
State-of-the-art electrodynamic tethers reach a steady electric current by using a bare segment to capture electrons passively from the ambient plasma (anodic contact) and an active electron emitter or a tether segment coated with a low-work-function material (cathodic contact) to emit electrons back and close the electrical circuit. This work prop...
Article
This works presents a system level analysis of a Deorbit Kit (DK) based on electrodynamic tether technology. The analysis is focused on two relevant scenarios for deorbiting space debris: (i) Earth Observation (EO) satellites with mass in the range of 700 kg -1000 kg and initial orbital altitude of 800 km and 98° inclination, and (ii) Mega Constell...
Article
Full-text available
Several claims appeared in the literature that a charged high-voltage capacitor produces thrust. This dates back to the so-called Biefeld-Brown effect that was later explained as a Corona-wind effect. However, part of the claim was that the capacitor still moves even if no ionization takes place and a dielectric is used. Recently, theories appeared...