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Reflectivity of a mirror in XUV spectral region (46.9 nm).
Schmidt, Jiří ; Koláček, Karel ; Štraus, Jaroslav ; Frolov, Oleksandr ; Prukner, Václav ; Melich, Radek ; Psota, Pavel ; Sobota, Jaroslav ; Fořt, Tomáš
A focusing mirror as an optical element is used in our applications that require light collection (e.g. for laser ablation studies). A knowledge of the mirror reflectivity is important for determination of focused laser pulse energy, or for determination of local fluencies near the laser focus. The reflectivity of our spherical focusing mirror with(/without) multi-layer coating was measured. Reflection coefficients of this mirror in a long period of time are also reported. Further, the incidence-angle dependence of the XUV reflectivity of flat mirrors is presented as well.
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ATMOSPHERIC JET BASED ON SURFACE STREAMER DIELECTRIC BARRIER DISCHARGE
Šimek, Milan ; Prukner, Václav
We designed novel axisymmetric atmospheric jet formed by effluents produced by surface streamers suitable for various applications. Filamentary streamers are produced by the amplitude-modulated AC surface dielectric barrier discharge. The SDBD-based jet makes use of the tangential injection of the working gas into a cylindrical chamber that induces a fast vortex flow through the discharge zone and expells excited/ionized/reactive species out of the discharge area through the axial orifice in the form of a jet spinning around its axis. The jet may be easily used to treat surfaces, expose biological samples or even be injected in liquids.
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Exploze drátku ve vodě
Prukner, Václav ; Koláček, Karel ; Schmidt, Jiří ; Frolov, Oleksandr ; Štraus, Jaroslav
The paper reports on the first experimental results of a new-built apparatus which is designed as soft X-ray source of coherent radiation with wavelength 14 nm. The radiation could be produced by the wire explosion in a liquid where the proximity of liquid wall can stabilize plasma similarly as proximity of solid wall stabilizes a Z-pinch in a capillary. The first part of this paper describes construction of the new device. In the second part are published first experimental data of wire explosion tests of the device which means time dependences of charging voltage and current.
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Čtyř-segmentová vakuová XUV fotodioda
Schmidt, Jiří ; Koláček, Karel ; Frolov, Oleksandr ; Prukner, Václav ; Štraus, Jaroslav
A soft X-ray/XUV diode (XRD) is a powerful diagnostic tool for system alignment, among others, in capillary discharge experiments, which generate directional soft x-ray radiation, eventually a laser pulse. In our experimental devices (CAPEX and CAPEX-U) we usually used PIN diode or vacuum photodiode (one-segment). These diagnostics are not very suitable, mainly because many shots (more than 50) are necessary to find the optical axis. During last year we have designed and manufactured a four-segment soft X-ray vacuum diode with a golden photocathode, which detects the soft X-ray radiation emitted in the axial direction. This new diagnostic tool is capable to locate the axis of soft X-ray laser in a few capillary shots (less than 10). The description and the experimental measurement of the four-segment soft X-ray vacuum diode are a subject of this paper.
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Využití modelových spekter ke stanovení vhodných parametrů kapilárního výboje pro zesílenou emisi Balmerova alfa – přechodu H–like N (13,4 nm)
Štraus, Jaroslav ; Koláček, Karel ; Schmidt, Jiří ; Frolov, Oleksandr ; Prukner, Václav
Our capillary-discharge driver CAPEX-U, as many other pulsed-power devices, requires very accurate triggering of high-voltage gas switch. Laser-triggered switches offer many advantages over electrical triggered ones in terms of reproducibility, reliability, suitability for multi-gap or multi-channel operation and electrical isolation from the main high-voltage pulse. Results on the simultaneous initiation of four-channel high voltage spark gap by a neodymium dopped yttrium aluminium garnet (Nd:YAG, λ=1064 nm) laser are presented. The switch is pressurised with SF6 and N2 and holds off voltage about 500 kV at a gap separation of 13 mm. Electrical parameters of the spark channels are obtained from the comparison of experimental and modelling (equivalent circuit) results.
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Multikanálové laserem spínané jiskřiště
Frolov, Oleksandr ; Koláček, Karel ; Schmidt, Jiří ; Štraus, Jaroslav ; Prukner, Václav
Our capillary-discharge driver CAPEX-U, as many other pulsed-power devices, requires very accurate triggering of high-voltage gas switch. Laser-triggered switches offer many advantages over electrical triggered ones in terms of reproducibility, reliability, suitability for multi-gap or multi-channel operation and electrical isolation from the main high-voltage pulse. Results on the simultaneous initiation of four-channel high voltage spark gap by a neodymium dopped yttrium aluminium garnet (Nd:YAG, λ=1064 nm) laser are presented. The switch is pressurised with SF6 and N2 and holds off voltage about 500 kV at a gap separation of 13 mm. Electrical parameters of the spark channels are obtained from the comparison of experimental and modelling (equivalent circuit) results.
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Experiment CAPEX-U: Současnost a Budoucnost
Frolov, Oleksandr ; Koláček, Karel ; Štraus, Jaroslav ; Schmidt, Jiří ; Boháček, Vladislav ; Prukner, Václav
A new pulse capillary discharge driver with a laser-triggered main spark gap has been developed. The assembled CAPEX-U device consists of a Marx generator, of a pulse forming line, a gas-filled laser-triggered spark gap and a ceramic capillary. Its design was supported by mapping of electrostatic fields in the most exposed regions and by analysis of an equivalent circuit. Operation of the laser-triggered spark gap was tested on a single-channel model. In the paper, the results of the modelling and of the first electrical tests of the whole device (capillary current and voltage at the end of pulse forming line) are presented.
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