Martin Tajmar

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• Prof. Dr.
• Professor (Full) at TU Dresden

Miniature satellites have gained popularity in recent years due to their cost-effectiveness in development. To fulfill diverse mission profiles, efficient and cost-effective propulsion systems are necessary. The proposed prototype thruster utilizes radiofrequency power and a new, ferrite-enhanced antenna for ionization. The structure, composed of a...

This work presents a process for the creation of emitter structures for liquid metal ion sources based on suspensions of iron and nickel in gallium-based room temperature liquid metal alloys. The process does not require needle etching or vacuum wetting of the emitter. Tip radii of less than 3 μm have been achieved. In addition, first measurements...

The rising deployment numbers of electric propulsion systems and the increased price of noble gas propellants have created the demand for alternative propellants. Iodine is a very promising candidate, which has already been successfully demonstrated with a variety of thruster types. The main challenge remains to design an iodine compatible neutrali...

With the introduction of aerographite in 2012, a new class of solar sail spacecrafts was devised in 2020. This class of spacecraft would give us the ability to travel into interstellar space for scientific purposes with significantly higher velocities and therefore reduced flight durations, compared to conventional propulsion systems. To ultimately...

Our investigations aim at the determination of ranges of reliable applicability of turbulence and turbulence/chemistry interaction models for the case of film cooling in liquid propellant rocket engines. Among the different models investigated have been a Reynolds-Averaged Navier-Stokes (RANS) approach with either k-or k-ω Reynolds Stress Model (RS...

A method for optimizing multiple responses in solenoids utilized in a magnetic nozzle assembly for an electric plasma thruster is presented. The primary goal is to minimize power usage while maintaining a sufficiently high magnetic flux density at the coil axis. This is especially critical during testing in a vacuum chamber, where heat dissipation...

Any means to control gravity like electromagnetism is currently out of reach by many orders of magnitude even under extreme laboratory conditions. Some often poorly executed experiments or pseudoscience theories appear from time to time claiming for example anomalous forces from capacitors that suggest a connection between the two fields. We develo...

Typical air-breathing electric propulsion (ABEP) concepts are often limited in terms of particle collection efficiency and power consumption, which significantly limits their intended use and operational altitude range. Since 2021, the Institute of Aerospace Engineering at the TU Dresden have been developing on a novel ABEP concept that uses specia...

Iodine exhibits promising characteristics as a propellant for electric propulsion systems. Its performance is comparable to xenon, yet it offers significant cost advantages. Moreover, it can be stored in a compact solid state and easily fed into the system through sublimation. Thruster operation has already been successfully demonstrated for the io...

A cold-gas test campaign has been conducted at the DLR’s P6.2 test bench in Lampoldshausen, with the objective of investigating the linear aerospike nozzle flow in interaction with secondary injection thrust vector control (SITVC). In this campaign, the influence of nozzle truncation, injection position and injection pressure on the nozzle surface...

We present the current state of the development of the electron emitter system for the planned in-orbit demonstration mission of the E.T.PACK-F project. Tasked with demonstrating the efficient deorbiting capabilities of electrodynamic tethers for satellites, the demo satellite requires an active electron emitter that can reliably operate at current...

At the Institute of Aerospace Engineering of TUD Dresden University of Technology, a compact heaterless hollow cathode with a C12A7 electride insert is under development. C12A7 electride has the advantage that it can be operated at lower temperatures, usually a few hundred degrees, compared to its state-of-the-art counterparts: barium oxide (BaO-W)...

Active electron emitters are an essential part of electrodynamic tether systems to return the flow of electrons to the space plasma environment. At TUD, several emitters based on the principle of hollow cathodes and field emission cathodes are under development. We provide an overview of the development history of these emitters and present three e...

Subgrid scale models for unresolved turbulent fluxes are investigated, with a focus on combustion for space propulsion applications. An extension to the gradient model is proposed, introducing a dependency on the local burning regimen. The dynamic behaviors of the model's coefficients are investigated, and scaling laws are studied. The discussed mo...

In the context of the European Space Agency (ESA)-funded activity, LUNAR In-Situ LANDing Structures (LUNAR ISLANDS), the feasibility of in-situ manufactured structures to decrease the exposure of surroundings to high-velocity particles of lunar regolith is explored. These particles get ejected as a consequence of the engine's plume interacting with...

Subgrid scale models for unresolved turbulent fluxes are investigated with a focus on combustion for space propulsion applications. An extension to the gradient model is proposed, introducing a dependency on the local burning regime. The dynamic behavior of the model's coefficients is investigated, and scaling laws are studied. The discussed models...

Experiments were performed in vacuum to examine a modified Kaluza–Klein theory. Originally proposed by Mbelek and Lachièze-Rey, the 5D Kaluza–Klein-ψ theory includes an external scalar field ψ to couple gravitational and electromagnetic fields and can be used to explain some misunderstood phenomena in physics. The theory predicts that a pendulum wi...

The electric solar wind sail, or E-sail, is a propellantless interplanetary propulsion system concept. By deflecting solar wind particles off their original course, it can generate a propulsive effect with nothing more than an electric charge. The high-voltage charge is applied to one or multiple centrifugally deployed hair-thin tethers, around whi...

Inertial electrostatic confinement fusion has developed into a widespread academic field since its inception in the 1950s and 1960s. This paper provides an overview of the different research groups (universities and research institutes) and companies involved in the field of IECF and their scientific publications. A list of over 970 publications fr...

Inertial electrostatic confinement fusion (IECF) devices often use two concentric spherical electrodes to converge ions in a plasma electrostatically. Using a highly transparent inner cathode, the ions can move through the cathode and collide at the center to undergo fusion reactions. This is a simple method to build a neutron source. Past research...

Hollow cathodes are crucial components for many electric propulsion systems used for space applications. However, they also represent a challenging and sometimes even limiting element for the propulsion systems. Particularly in recent times when alternative propellants are under evaluation for the thruster, and the design and the limits of the cath...

This study investigates the application of Advanced Nozzles to Reusable Launch Vehicles (RLVs) through Mission Analysis, MDO and GNC Missionisation tools for autonomous re-entry vehicles. In this context, it is offered an assessment of Mission and Recovery Capabilities for an adapted version of RETALT1, an European VTVL-RLV concept (H2020 project)...

For the operation of electric propulsion systems in space, efficient electron sources are crucial components. Hollow cathodes have been established for many applications since they allow sufficient current ranges at reasonable power requirements and have been proven to operate for several thousands of hours. New approaches are being evaluated to im...

CubeSats have a 65% success rate. Failures derive from design mistake or components malfunctions. To improve the success rate, Technical University of Dresden and FHWN (University of Applied Sciences Wiener Neustadt) developed GREATCUBE+, a software tool for the conceptual design of CubeSats. Its layered structure comprises three levels: empirical,...

One of the main challenges for sustainable lunar operations are the potential adverse effects on surface infra-structure caused by regolith particles, covering the lunar surface. Due to the lack of atmosphere, these particles are not affected by weathering and remain sharp and jagged. Thus, they can damage lander and/or launch vehi-cles whose engin...

To gain access to very low Earth orbits (VLEO) for low latency communications or more detailed Earth observation, air-breathing electric propulsion (ABEP) represents an interesting key technology. Current designs of ABEP thrusters have an active ionization stage that requires some additional electrical power for particle ionization. This paper prov...

Rotating detonation engines (RDEs) emerge as a promising technology in the field of propulsion, potentially offering improved efficiency compared to traditional combustion engines. Nonetheless, the combustion process within RDEs currently lacks a comprehensive understanding. This study endeavors to bridge this knowledge gap by examining the flow be...

Within the SR Dorado-project, which started in July 2022, a sounding rocket and its corresponding ground support equipment and test facilities are being developed and manufactured. This work is done mainly by undergraduate students at Technische Universität Dresden in cooperation with STAR Dresden, the student Space Flight Working Group in Dresden....

With interstellar mission concepts now being under study by various space agencies and institutions, a feasible and worthy interstellar precursor mission concept will be key to the success of the long shot. Here we investigate interstellar-bound trajectories of solar sails made of the ultra-light material aerographite, known for its low density (0....

The electric solar wind sail, or E-sail, is a novel deep space propulsion concept which has not been demonstrated in space yet. While the solar wind is the authentic operational environment of the electric sail, its fundamentals can be demonstrated in the ionosphere where the E-sail can be used as a plasma brake for deorbiting. Two missions to be l...

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 by using an EBI-DNS solver within an OpenFOAM frame. The transport of species is resolved with finite-rate chemistry by using a comp...

Concurrent engineering is an approach to the development of complex systems that is characterised by direct communication between the disciplines involved. Key to this approach is the access to the most current design data by all participants at all times. This can be done via a dedicated software solution, for which both commercial and open-source...

The experimental campaign at Technische Universität Dresden tests the performance of annular-aerospike, dual-bell and expansion-deflection nozzles compared with conventional nozzles in various subsonic counter-flow regimes and atmospheric conditions. This manuscript offers comparative results between advanced nozzles (aerospike and expansion-deflec...

A cold-gas test campaign has been conducted at the DLR’s P6.2 test bench in Lampoldshausen to investigate linear aerospike nozzles in interaction with secondary injection thrust vector control (SITVC). Nozzle truncation and injection position are analysed w.r.t. their influence on the nozzle surface and base pressure. While the effects of injection...

CubeSats are a type of spacecraft which have become popular since the early 2000. They are known for their quick development time and low cost, when comparing them to larger satellites. However, there is a significant drawback which has been recorded during these years of operations, namely an high failure rate which turns almost half of them into...

In this work, we present observations about the transport of 15.2 keV electrons with a beam current of 21 μA through macroscopic dielectric capillaries. These capillaries are made of borosilicate glass with an inner diameter of about 6 mm, and samples with a bending angle of 90° and 360° were investigated. The electron gun was adjusted, and the bea...

Consumable-free electron emitters are presently not feasible for autonomous tether-based deorbit devices such as E.T.PACK due to their power requirement. The bare-photovoltaic-tether (BPT) concept combines the bare tether electron collection with a tether segment, coated with thin film Copper Indium Gallium Selenide solar cells to harvest additiona...

Trapping ions, such as deuterium and tritium, inside a potential well to generate neutrons is a well-established technology through electric and magnetic fields via the inertial electrostatic confinement fusion (IECF) and the tokamak, respectively. In the IECF, the straightforward configuration is a concentric cathode connected to a negative bias,...

When it comes to deorbiting spacecraft at their end of life to avoid future space debris, electrodynamic tethers (ET) are promising, offering fully propellantless operation. However, generating thrust or drag requires the ET to close the electric circuit with the surrounding plasma environment with a cathode, which to date still requires an externa...

This contribution presents an overview of the research and development activities within the research group for Space Transportation, which is part of the Institute of Aerospace Engineering at Technische Universität Dresden. The research focuses mainly on chemical propulsion systems, including the cutting edge academic investigations on additively...

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...

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 behavio...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

Air-breathing electric propulsion (ABEP) systems generate thrust by using the residual atmosphere as a propellant in Very Low Earth Orbits (VLEO). A nearly continuous, small thrust is required to overcome the drag forces acting on the satellite as a result of the residual atmosphere. Conventional ABEP concepts are based on three-stage systems: Firs...

Simulating the Low Earth Orbit (LEO) environment in terrestrial vacuum chambers is essential to determine interactions between LEO space environment and spacecrafts, like degradation of materials, damages due to radiation, collisions with micro meteorites or space debris as well as buildup of electric charges which can damage sensitive electronics....

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...

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...

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...

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...

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....

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...

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...

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...

„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...

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...

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...

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...

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...

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...

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...

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...

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...