Design, Verification and Validation of a Micropropulsion Thrust Stand

At the chair of Space Systems Engineering, students and staff work on the development of small propulsion systems in a wide thrust capability. Especially in recent years low thrust propulsion systems have gained an increased amount of interest in the entire department of Space Engineering. To support the development of these propulsion systems, there is a need for the testing of micropropulsion systems that provide a thrust in the 1 ?N to 5 mN range. This capability complements the existing measurement equipment of the Delft Aerospace Rocket Thrust Stand facility of 0.5 mN to 1 N. To provide a solution to this need, the research question for this research is phrased as: "How can the DARTS facility be upgraded to measure thrust levels in the 1 ?N to 5 mN range and impulse bits in the 1 ?Ns to 1 mNs range?". Using numerical modelling the answer to that question is found in an upgraded design of the TB-2m thrust stand that was developed in 2010 by Perez-Grande. By introducing several improvements, amongst which are the replacement of the sensor system by a capacitive displacement sensor and the use of a segmented counter mass, the range of the TB-2m has been extended and the accuracy has been improved to meet the new requirements. A complementary calibration system is designed that allows an in situ calibration for the measurement of both the thrust and impulse bits. Where typical calibration actuators supply a force that is non-linear with engagement distance and have to rely on displacement measurements to linearize the calibration force, the new actuator is able to provide a force that is independent on the distance to the target. Using a specially designed solenoid that has a linearly varying turn-density along its length, the magnetic field is shaped to provide a constant magnetic gradient. The thrust stand and calibration system are manufactured and tested. Using a previously tested cold gas thruster that is provided by Bradford Engineering, the complete thrust measurement system is validated with hardware-in-the-loop. This process has shown that the pendulum is in a state constant of oscillation. It is expected that this oscillation is removed by the introduction of a Foucault damper in the next design iteration. The validation process has shown that the thrust range is on par with the requirements. Also impulse bits can be measured, but the constant state of oscillation prohibited the detection of the smallest impulse bits of 1 ?Ns. Future experiments have to show whether the required and predicted accuracies are achieved.Space Systems EngineeringSpace EngineeringAerospace Engineerin

Towards a heat transfer based distance sensor for measuring sub-micrometer separations

In this thesis a proof-of-principle demonstration is developed that uses the heat flux between a probe and a sample as a proxy for their separation. The proposed architecture uses a probe that consists of a bilayer cantilever with an attached sphere at its free end. The deflection of the cantilever that is caused by the heat input is measured using the optical beam deflection method. To eliminate temperature dependent effects the temperatures of the probe and the sample are kept constant. Moreover, a total internal reflection microscopy is included to provide an independent measurement of the separation between the probe and the sample. This architecture allows the measurement of the heat flux as a function of only the separation. An equation is derived that relates the output signal of the instrument directly to the heat flux that is absorbed by the probe. It couples the top-level design parameters to the system output and is used to study and design the separate elements. In addition to the design of the instrument, the research contributes a detailed study of the influences of the microsphere and the microcantilever on the heat flux measurement. Structural Optimization and Mechanic

Design of a calorimeter for near-field heat transfer measurements and thermal scanning probe microscopy

Multilayer cantilever beams are used in the measurement of near-field radiative heat transfer. The materials and dimensions of the cantilever probe are chosen in order to improve system performance in terms of sensitivity and noise. This is done using an analytical model that describes the thermo-mechanical and mechanical behavior of the cantilever and its influences at the system level. In the design, the optical reflectance and the sensitivity of cantilever rotation to the heat input are maximized under constraints for thermal noise, temperature drift, and a lower bound for the spring constant. The analytical model is verified using finite element analysis, which shows that the effects of radiative losses to the environment are insignificant for design purposes, while the effects of ignoring three-dimensional heat flow introduces larger errors. Moreover, the finite element analysis shows that the designed probes are up to 41 times more sensitive than the often used commercial-of-the-shelf benchmark and have a four times lower thermal noise. Experimental validation of the designed probes shows good agreement with the theoretical values for sensitivity. However, the most sensitive designs were found to be susceptible to damage due to overheating and carbon contamination. Structural Optimization and Mechanic

Non-contact distance measurement and profilometry using thermal near-field radiation towards a high resolution inspection and metrology solution

Optical near-field technologies such as solid immersion lenses and hyperlenses are candidate solutions for high resolution and high throughput wafer inspection and metrology for the next technology nodes. Besides sub-diffraction limited optical performance, these concepts share the necessity of extreme proximity to the sample at distances that are measured in tens of nanometers. For the instrument this poses two major challenges: 1) how to measure the distance to the sample? and 2) how to position accurately and at high speed? For the first challenge near-field thermal radiation is proposed as a mechanism for an integrated distance sensor (patent pending). This sensor is realized by making a sensitive calorimeter (accuracy of 2:31nW root sum squared). When used for distance measurement an equivalent uncertainty of 1nm can be achieved for distances smaller than 100 nm. By scanning the distance sensor over the sample, thermal profilometry is realized, which can be used to inspect surfaces in a non-intrusive and non-contact way. This reduces wear of the probe and minimizes the likelihood of damaging the sample.Structural Optimization and Mechanic

Towards an effective reduction of intensity noise in laser diodes

Structural Optimization and Mechanic

A new horizon: Using heat to measure distance in high performance metrology solutions

Structural Optimization and Mechanic

Reduction of laser diode intensity noise in optical beam defection systems

Structural Optimization and Mechanic

Meta-instrument: An opto-mechanical platform for imaging near-field optical instruments

Structural Optimization and Mechanic

Advanced Nano Telescope: A cornerstone solution in Earth Observation

Recent developments in satellite industry gaining strong attention are so called nanosatellites. These small satellites, with sizes of about a milk carton, are easy to build and much more adordable, promising great advantages for future space missions. Up until today no reliable mid-resolution Earth observation instrument has been build that can be operated on such a small, low cost satellite. In light of these events this years Design Synthesis Exercise group 9 developed such a camera system which is called the Advanced Nano Telescope (ANT) providing a novel instrument that can be carried as payload by nanosatellites. The novelty lies in the applied principles of miniaturization and intelligent distribution in order to compete with a single large scale instrument. The strength of the instrument developed lies in the fact that it can take images with 7.5 meter resolution, requiring a volume of only 10 x 10 x 15 cm at an estimated cost about EUR 100,000. The small dimensions allow it to ft into half a standard 3 unit CubeSat such as the Delfi-n3Xt. The resolution is achieved by limiting the system to sense a narrow band around a single color, making use of a well designed combination of lenses and mirrors folding the light path enabling a long focal length. The thermo-mechanical design is designed such that the instrument functions in the hostile space environment from altitudes of 540 to 1440 km altitude. ANT has a smart modular structure that allows a mission designer to simply purchase the instrument and plug it into a satellite. Since all required electronic components are already present in the instrument the host satellite only needs to provide power and pointing capability to be able to achieve a fully functional system. One ANT by itself can take mid-resolution mono-chromatic images, but its real value will show when it is launched in a constellation, something which the low cost per unit allows. Multiple constellations of ANT's can outperform single satellites systems with similar ground resolutions in terms of development time, construction costs, operating costs and revisit time, enabling color composite imagery and promising improved availability at a lower price per image. Furthermore dedicated relay satellites can be added to achieve higher data rates. Overall catastrophic failures are eliminated as multiple satellites performing independent tasks are present offering redundancy and the possibility of replacement. The conclusion is that the system developed holds a promising future with a wide range of possible applications. The instrument itself is striking due to its apparently simple but intelligent and robust design enabling Earth observation without the need of expensive large scale satellites. For future work it is recommended to further develop the concept in order to prototype and test the actual performance of the ANT instrument.Bachelor Aerospace EngineeringSpace EngineeringAerospace Engineerin