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Double pulse capillary discharge assessment for nitrogen soft X-ray laser.
Hübner, Jakub ; Nevrkla, M.
The work examines possibilities of capillary discharge pinching plasma driven by combination of two electric current pulses ("pedestal" slow exponentially damped sinus t1/4 > 200 ns, peak current Ipeak < 50 kA and fast triangular pulse with a rise time about 38 ns, Ipeak > 60 kA) to obtain the maximum possible gain at wavelength l = 13.4 nm (hydrogen-like nitrogen recombination scheme). The optimal initial density ρ0 (or pressure) and start time tstart of second triangular pulse (second pulse start at peak current Ipeak of the first pulse) were determined for two capillary radii (0.5 and 1 cm) and four current peaks of the first pulse (20, 30, 40 and 50 kA).\n
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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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