Ústav fyziky plazmatu

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2019-02-13
17:43
Electric probe measurements in the anode area of a DC arc plasma torch at low pressure
Ondáč, Peter ; Mašláni, Alan ; Hrabovský, Milan
We measured radial profiles of the electric field, plasma electrical potential and electron temperature in the hot anode area of a hybrid water-argon DC arc plasma torch with an external anode. The measurements were made under different values of the ambient pressure, during the restrike mode with a constricted anode arc attachment or during a supersonic mode with a diffuse anode arc attachment. The results provide first experimental data on plasma electrical potential in that anode area.

Úplný záznam
2019-02-13
17:43
Realizace tenkých vrstev na optických komponentech
Budasz, Jiří
Zpráva se zabývá realizací tenkých vrstev na optických elementech určených pro funkční vzorky a prototypy. Popisuje rovněž zátěžové testování soustav vrstev na vzorcích.

Úplný záznam
2019-02-13
17:43
Vývoj procesu mytí a příprava povrchu před depozicí
Budasz, Jiří
Zpráva popisuje vývoj mycího postupu substrátů pro výrobu superodrazných zrcadel. Zahrnuje také vývoj procesu ošetření povrchu ve vakuu.

Úplný záznam
2019-02-13
17:43
Large displacement and deformation measurement by frequency sweeping digital holography
Psota, P. ; Lédl, Vít ; Kaván, František ; Matoušek, O. ; Doleček, R.
Recently, a digital holographic method called Frequency Sweeping Digital Holography (FSDH) for high precision measurements of surface topography of mechanical parts has been introduced. The greatest advantage of the presented FSDH is the fact that the measurement is absolute. i.e. optical path difference is independently retrieved in every single pixel. This approach can therefore be used also for measurement of large displacements and deformation. FSDH is particularly suitable in cases where the common digital holographic methods fail due to e.g. 2π unambiguity problem or speckle decorrelation. Measurement method principles, setup details, an some features of the method are discussed.\n

Úplný záznam
2019-02-13
17:43
Surface profilometry by digital holography
Psota, Pavel ; Lédl, Vít ; Kaván, František ; Matoušek, O. ; Mokrý, P.
This paper presents newly developed method for measurement of surface topography based on frequency scanning digital holography. Digital holography allows for direct computation of the phase field of the wavefront scattered by an object. A tuning of the light source optical frequency results in linear phase variation with respect to the optical frequency. Slope of the linear function in every single pixel corresponds to absolute measurement of optical path difference and thus topography map of the surface can be retrieved. Principle of this contactless method is introduced and experimentally verified. The method can be used for measurement of complex geometries of common manufacturing parts as well as for topography measurement of complex composite structures, and active acoustic metasurfaces.

Úplný záznam
2019-02-13
17:43
Využití holografie pro měření a charakterizaci povrchu
Kaván, František
Tento výzkum je zaměřen na využití digitální holografie pro měření tvaru optických a jiných ploch. Pro první experimenty jsme použili standardní metodu dvojvlnné holografické interferometrie. Ta posloužila jako reference. Hlavním zaměřením je však Frequency Sweeping Digital Holography (FSDH) neboli skenovací digitální holografie, která využívá plynule přeladitelných DFB laserových diod. Přesnost této metody lze dále vylepšit spojením měření z více vlnových délek - více diod. Při spojení je možno pomocí této metody dosáhnout přesnosti až 2 µm.

Úplný záznam
2019-01-07
14:42
NEOSTEL Fly-Eye Optics Alignment Aid System (AAS) - design
Budasz, Jiří ; Lédl, Vít ; Pleštil, Jan ; Steiger, Kateřina ; Steiger, Lukáš ; Václavík, Jan ; Veselý, Martin ; Vít, T.
The aim of this document is to describe the design of the Fly-Eye Optics Alignment Aid System.

Úplný záznam
2019-01-07
14:42
On tungsten spraying using inductively coupled plasma system - First results
Klečka, Jakub ; Mušálek, Radek ; Vilémová, Monika ; Lukáč, František
Thanks to its unique properties such as high melting point and density, tungsten and tungsten-based alloys are commonly used in a wide range of applications. Among others, these materials are promising candidates for the plasma facing components in the future fusion reactors. One of considered ways of production of these parts is plasma spraying. There are however several limitations for conventional gas stabilized torches, mainly in plasma enthalpy (i.e. the ability to efficiently melt tungsten particles in considerable feed rates) and susceptibility of tungsten to oxidation (which complicates spraying in oxidizing open-air atmosphere). The radio frequency inductively coupled plasma torch (RF-ICP) is a unique system which can potentially overcome both these problems and can be used for efficient tungsten spraying. The tungsten powder, which can be finer than the one used for the conventional systems, is fed axially into the hot plasma core; both factors lead to a more efficient melting of the particles. The deposition is performed in a chamber with controlled atmosphere of inert gas or decreased pressure, the oxidation is therefore suppressed. In this first study carried out with the newly commissioned RF-ICP system TekSpray 15 (Tekna), samples of tungsten coatings on graphite substrates were prepared. The X-ray diffraction and SEM images of the free surfaces and cross-sections were obtained, documenting high purity of the deposits and appropriate flattening of the splats leading to a dense coating microstructure. The effect of substrate preheating on the microstructure, porosity and hardness was also studied.

Úplný záznam
2019-01-07
14:42
Thin nitride layers as permeation barriers
Veverka, Jakub ; Matějíček, Jiří ; Lukáč, František ; Pospíšil, D. ; Cvrček, L. ; Nemanic, V.
Permeation barriers represent one of the crucial fields in materials development for thermonuclear fusion. Primary objective of the barriers is to suppress the permeation of hydrogen isotopes (mainly tritium) from future thermonuclear fusion facilities. Secondary objective is to reduce their retention in structural materials. Expected reactor conditions put high demands on the material, as well as on the final barrier quality. Key properties are tritium permeation reduction, absence of defects (especially cracks), high-temperature stability and corrossion resistance, and compatibility with structural materials (mostly ferritic-martensitic steels). Thin nitride layers, identified as promising permeation barriers, were prepared by diffusion-based nitridation and physical vapour deposition (PVD), and characterized.

Úplný záznam
2019-01-07
14:42
Study on polishing of CaF2 plane-parallel elements
Procháska, František ; Thoř, Tomáš ; Šípová, Gabriela
Determination of technological procedure for processing of plane-parallel and plano-convex CaF2 optical elements. That includes optical polishing as well as preparation of samples for polishing, i.e. cementing and grinding.

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