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SMV-2023-42: Materials for thermal management
Králík, Tomáš
This contract research dealt with so-called solar white coatings with a very different ability to absorb visible radiation and emit thermal radiation. We have studied special coatings designed for the space environment with high emissivity in the field of thermal radiation and at the same time low absorption of radiation originating from the sun or reflected from cosmic bodies. This type of coating is intended for passive thermoregulation of parts of apparatus moving in the space environment. The aim was to determine the so-called total hemispheric emissivity of each of the samples at the required temperatures. For these coatings, the client's goal was also to evaluate the effect of the morphology of the sample on the resulting emission of thermal radiation. Namely, we tested the flat and pyramidal structured surface of the base material. This unique research required a special modification of the supplied samples, modification of the dedicated method for measuring emissivity and absorptivity at cryogenic temperatures, as well as a new procedure for calibration and evaluation of the received data. We used a previously developed shielding ring around the perimeter of the samples to cover the perimeter of the structured samples, which prevented part of the measured thermal radiation from escaping. The results of this research will be used in the design of the CO2M space mission for monitoring CO2 emissions.
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SMV-2023-41: Absorptive coatings for quantum computers
Králík, Tomáš
This contract research focused on the thermal analysis of absorptive layers created by anodic oxidation on aluminium alloy, which are optimized for use at extremely low temperatures. These specific layers were designed for the low-temperature parts of quantum computers, where they play a key role in eliminating the reflection of thermal radiation from the hotter areas of the computer cryostat to the ultra-low temperature areas. Other key requirements for these absorptive layers are high thermal conductivity, necessary for efficient heat transfer within a quantum computer, good mechanical stability and extremely low outgassing to ensure long-term functional behaviour of the layers in challenging low-temperature conditions. The goal of this research was not only to verify the total hemispheric emissivity of three specific types of coatings in the temperature range from 10 K to 300 K. In this case, emissivity is a suitable indicator of the thermal absorptive behaviour of the layer. A study of the emissivity of these layers in the entire spectrum of temperature conditions relevant for quantum computers was carried out. This extensive analysis was intended to provide an insight into the suitability of these absorptive layers for applications in the field of low-temperature technologies, with an emphasis on the requirements of quantum computers.
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Contemporary Health and Safety at Work Problems and their Influence on the Functioning of an Organization
Králik, Tomáš ; Svěrák, Tomáš (referee) ; Novák, Jaromír (advisor)
This diploma thesis elaborated on the subject „Contemporary Health and Safety at Work Problems and their Influence on the Functioning of an Organization“ focuses on the description of contemporary state of Health and safety at work problems in work activities, where the source of risk is represented by chemical substances, from the point of view of a company. The thesis sets out a view of legislative definition for the mentioned topic and also the possible application of safety at work management programs. This part also includes a summary description of risk analysis methods. In the practical part of the thesis, there is an organizational directive for a fictive company engaged in chemical production made. This directive will identify possible occupational risks resulting from the manufacturing process, and it will also evaluate the amount of risk for particular work activities in conjunction with hazard factors. The next part of the thesis contains a proposal of measures for risk reduction, based upon the previously mentioned evaluation. In the final part of the thesis, the author contemplates the possibilities of health and safety at work system improvement.
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Terrorism and its context
Králik, Tomáš ; Mika, Otakar Jiří (referee) ; Novák, Jaromír (advisor)
Thesis deals with terrorism and its context from the perspective of defining, historical evolution, potential causes and impacts of terrorism on security environment. The conclusion of thesis is focused on possible forms of terrorism and impacts on human society and possible means and collaboration in fight against terrorism.
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SMV-2022-43: Absorptivity and emissivity of materials for use in space
Králík, Tomáš
This contractual research was aimed at verifying the thermal radiation properties of the emissivity of coatings and covering foils for space probes. Half of the experiments were focused on thermal regulation coatings, the purpose of which is to passively maintain the optimal temperature of the device, the balance between thermal radiation and absorption of visible radiation. Some foils had unique thermochromic properties, where their thermal radiative properties change sharply with their own temperature. The second part of the research was focused on the effect of contamination of a clean metal surface with dust simulating lunar regolith on the absorption of thermal radiation. As part of this research, five differently contaminated surfaces were measured. This unique data will enable the contractor to better design apparatus for work on the surface of the Moon or other planets. The contractor selected and supplied\nsamples of materials in the form of foils and coated sheets, which had to be modified into a sample suitable for the apparatus operated at the ISI Brno. A material labelled EAC‐1A was used as a lunar regolith simulant. The goal of the project was to evaluate the so‐called total hemispheric emissivity or absorptivity in the temperature range from 20 K to 300 K.
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SMV-2022-42: Emissivity of coatings for space mission ARIEL
Králík, Tomáš
This contractual research was aimed at verifying the thermal emissivity of materials planned for use in the optical system of the ARIEL infrared telescope located in orbit around the earth. The contractor selected several samples of the coating with high light absorption. However, the thermal radiation properties of this coating were not yet known. The goal of the project was to evaluate the so-called total hemispheric emissivity in the temperature range from 20 K to 300 K. The results will enable the customer to model the temperature distribution inside the optical path of the telescope.
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Low-temperature emissivity of thin Al2O3 layers deposited on copper substrate
Frolec, Jiří ; Králík, Tomáš ; Nyman, L. ; Pudas, M. ; Kallio, E.
Copper is commonly used in cryogenic systems due to its high thermal and electrical conductivity along with excellent solderability. Very low emissivity values of copper surface also reduce in cryogenic systems heat load transferred by thermal radiation. These values may be, however, enhanced by a prospective coating, deposited usually in order to prevent chemical changes on highly reactive copper surface. This paper focuses on protective layers of Al2O3 with thicknesses up to 28 nm, deposited on polished copper. We measured total hemispherical emissivity at cryogenic temperatures before and after the coating process. Contribution of Al2O3 layer to original copper emissivity increased with rising temperature of the layer and with the layer thickness. However, emissivity of the coated copper stayed below 2%, allowing usage of the coated copper in systems where low heat load by thermal radiation is needed. Preliminary tests with oxygen plasma shows that deposited layers can effectively protect the copper surface against oxidation and maintain the original thermal-radiative properties.
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SMV-2021-42: Thermal properties of MLI spacers
Králík, Tomáš
Super insulations are special types of thermal insulations used in industrial applications of low temperatures and the apparatuses for the exploration of Space. They are composed of many layers of reflective foils interleaved by thin fabric- the spacer. The goal of the project was the experimental evaluation of the heat transfer across the sample of the spacer used in the super insulation. The evaluation was done under defined compression of the sample in vacuum and temperatures in the range from 10 K to 300 K. The thickness of the sample was simultaneously measured together with the thermal properties of the sample by using electrical capacity. All measurements were done in a unique apparatus Spaceman at conditions simulating the real environment where the materials are used.
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SMV-2021-40: Thermal emission of CFRP material in vaccum
Králík, Tomáš
This contractual research was focused on the evaluation of the thermal emissivity of material for the structural beam of the space telescope ARIEL. The material is a carbon fibre composite. The knowledge of the thermal emissivity of this material is important for modelling the temperature of the telescope. Its temperature should be passively kept at 55 K only by thermal radiation. The goal of the project was to evaluate the total hemispherical emissivity of the composite in the temperature range from 20 to 300 K. The data was used to decide if the structural beams should be coated with an additional highly emissive layer or not.
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SMV-2021-41: Emissivity of the materials for space missions
Králík, Tomáš
This contractual research was focused on evaluation of the thermal emissivity of materials used for space probes to ensure optimal passive thermal control of the device. The ordering party has chosen several types of materials in a form of foils or coated sheets. The materials were shaped to fit in the measurement apparatus. Goal of the project was to evaluate the total hemispherical emissivity in temperature range from 20 to 300 K. The results will help the ordering party to model the temperature distribution cooled in space only by the thermal radiation.
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