N. Vogel

Publications (16)11.94 Total impact

• Article: Refraction and absorption shadow imaging of the vacuum arc cathode spot at an atomic resonance line of cathode vapors

  A.V. Batrakov, B. Juttner, S. Popov, D.I. Proskurovsky, N. Vogel
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  ABSTRACT: The resonance laser interference and absorption shadow imaging combined with the high-speed IMACON 468 camera was used for studying the dynamics of metal vapors supply into the cathode spot plasma at operation of low-current vacuum arc discharge with liquid-metal cathode. The experiments were performed with a capillary-type liquid-metal cathode made of gallium-indium alloy. The data are analyzed in terms of cyclicity of cathode spot operation. Two distinct modes of cathode spot operation were discerned in images, which are the explosive mode and the steady mode. The explosive mode takes the 2%-part of the spot operation cycle. It follows by the steady mode (∼20% of the spot cycle time). The rest time the spot is transparent at the resonant line of cathode vapors. At a discharge current above 50A, the spot is always in the transparent mode.
  IEEE Transactions on Plasma Science 11/2005; · 1.17 Impact Factor
• Article: Plasma parameters of an arc cathode spot at the low-current vacuum discharge

  A. Batrakov, S. Popov, N. Vogel, B. Juttner, D. Proskurovsky
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  ABSTRACT: This paper is devoted to the results of an experimental study of plasma parameters of cathode spot burning on a liquid-metal cathode in vacuum at a low-current (less than 200 A) vacuum arc discharge. Picosecond laser interferometry and absorption shadow imaging were used in a single experiment. Plasma fragments as dense as 10²⁶ m^-3 were observed at discharge currents less than 50 A. Such fragments were never observed in arc discharges with currents higher than 100 A or in the breakdown stage of the discharge.
  IEEE Transactions on Plasma Science 11/2003; · 1.17 Impact Factor
• Article: Resonant atomic interfero- and shadowgraphy of vacuum arc with gallium cathode

  A. Batrakov, B. Juttner, S. Popov, D. Proskurovsky, N. Vogel
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  ABSTRACT: The mechanism of the emission of neutral atoms of the cathode material into the discharge gap of a microsecond low-current vacuum arc with a liquid Ga cathode has been investigated by the method of subnanosecond resonance laser interfero- and shadowgraphy. It has been shown that the cathode material vaporization has a pronounced nonstationary character and occurs both isotropically and in the form of constricted weakly ionized jets with the atom concentration in a jet over 10¹⁷cm^-3.
  IEEE Transactions on Plasma Science 11/2003; · 1.17 Impact Factor
• Article: Interferograms of a cathode spot plasma obtained with a picosecond laser

  A. Batrakov, N. Vogel, S. Popov, D. Proskurovsky, D. Kudimov, D. Nikitine
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  ABSTRACT: Cathode spot plasmas as well as "plasma balls"-moving dense plasma blocks in vacuum arcs-were investigated by laser interferometry and absorption photography with high spatial (1.2 μm) and temporal (100 ps) resolution. The discharge was initiated between a needle-type cathode and plane anode with a cathode-anode distance of a few millimeters. The duration of the discharges was about 10 ms and the current up to 100 A. Picosecond interferometry yielded spatial-temporal electron density distributions in the arc phase of the cathode spot. An absolute electron density up to 2×10²⁶ m^-3 and plasma temperature about 1 eV in narrow plasma jets with a diameter about 5 μm were estimated
  IEEE Transactions on Plasma Science 03/2002; · 1.17 Impact Factor
• Conference Proceeding: Subnanosecond resonance laser diagnostics of the cathode spot region of low-current vacuum discharge

  S. Popov, N. Vogel, B. Juttner
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  ABSTRACT: In this paper, the supplying of neutral atoms of the cathode material into the discharge gap at low-current microsecond vacuum arc with liquid Ga cathode was investigated employing the method of subnanosecond resonance laser diagnostics. It has been shown that vapours ejection has an essentially nonstationary character and it occurs both isotropically and in the form of contracted low-ionized plasma jets with atomic concentration of more than 10¹⁷ cm^-3.
  Discharges and Electrical Insulation in Vacuum, 2002. 20th International Symposium on; 02/2002
• Conference Proceeding: Diagnostics of laser-induced spark discharges in air and vacuum

  N. Vogel, D. Nikitine, T. Blaudeck
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  ABSTRACT: In the authors' work, they present the results of their studies of self-channeling processes generated by interaction of an intense laser pulse (10¹⁵ W/cm²) with metallic and double-layer targets both in gas atmosphere and in vacuum. They report about measurements of intense X-ray radiation, the evolution of the plasma density in laser-produced plasmas by means of pulsed interferometry and shadowgraphy and the evidence of fast ions generated in plasma channels, detected by means of a plastic nuclear track detector CR-39.
  Discharges and Electrical Insulation in Vacuum, 2002. 20th International Symposium on; 02/2002
• Article: Measurements of the current density in arc cathode spots from the Zeeman splitting of emission lines

  N Vogel, B Juttner
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  ABSTRACT: Copper resonance lines from low-current break arcs in a vacuum and in air have been registered with a spectral resolution <0.015 nm. Two typical profile types have been found: Stark-broadened single lines and lines split into several components. The first type is ascribed to radiation from the plasma column outside the spots, whereas the split lines are associated with the actual spot. Looking side-on, only the first profile type could be observed. In a vacuum, the Doppler shift of these lines indicates a directed velocity of (1.5-4.5)*104 ms-1. Looking end-on through a cathode hole both types of line could be distinguished. Interpreting the line splitting by the Zeeman effect, the authors conclude that there is an arc spot current density >1011 Am-2 in a vacuum as well as in air.
  Journal of Physics D Applied Physics 07/2000; 24(6):922. · 2.54 Impact Factor
• Conference Proceeding: Experimental investigation of stochastic pulsation and formation oflight bullets in a laser-produced plasmas

  N. Vogel, N. Kochan
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  ABSTRACT: Generation of an extremely stable light bullets in a preformed plasma near critical density has been observed experimentally. Optical probing measurements indicate the formation of a pulsating channel, typically of about 5 μm in diameter, directed towards to a heating laser beam, as well as a disconnected massive plasma blocks moving also towards to laser beam. The authors report time-resolved results obtained by interferometric and absorption measurements for the interaction of a 100 ps Nd:YAG laser beam at λ=1064 nm with a metallic target in air. The formation of density ripples, light bullets and their temporal evolution was investigated with high spatial and temporal evolution. The velocity of such dense plasma blocks reaches values of order of 4.5×10 8 cm/s. And they are stable during the acceleration and propagation in air. Self-generated magnetic fields up to 8 MG were observed by means of Faraday rotation of a probe laser beam. They are “frozen"” in moving plasma blocks
  Discharges and Electrical Insulation in Vacuum, 2000. Proceedings. ISDEIV. XIXth International Symposium on; 02/2000
• Article: The X-ray radiation from cathode spot fragments in laser-induced vacuum discharges

  N. Vogel
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  ABSTRACT: The temporal evolution of X-ray emission of laser-induced discharges was investigated by means of a picosecond X-ray streak camera. Point-like structures with small divergence and thin hot layers of intense X-ray radiation with life time from 30 ps to 1.5 ns in a spectral range 100 eV-10 keV have been found in a comparatively low voltage vacuum discharge (U&ap;150 V-2.7 kV) initiated by picosecond laser beam. The radiation of laser induced breakdown was investigated just after breakdown as well as with a delay time (up to 20 ns) relative to the ignition point by the laser beam in order to eliminate the X-ray radiation coming from the laser-produced plasma
  IEEE Transactions on Plasma Science 09/1999; · 1.17 Impact Factor
• Article: The X-ray emission from vacuum discharge micro fragments at comparatively low applied voltages

  N. Vogel, V. Skvortsov
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  ABSTRACT: The temporal evolution of X-ray emission of laser-induced discharges was investigated by means of a picosecond X-ray streak camera. Point-like structures with a divergence of order 10^-7 and thin hot layers of intense X-ray radiation with life time from 30 ps to 1.5 ns in spectral range 100 eV-10 keV have been found in a comparatively low voltage vacuum discharge (U=150 V-2.7 kV) initiated by picosecond laser beam. Computer simulation shows that such X-ray generation is connected with a matter transition into extreme states when in local microvolumes of dense current carrying plasma the pressures can exceed values of 5 Mbar and the specific internal energies &epsi;&ges;1 MJ/g
  IEEE Transactions on Plasma Science 03/1999; · 1.17 Impact Factor
• Source

  Available from: pppl.gov

  Conference Proceeding: Laser-induced discharges in vacuum and air: diagnostics of an extreme states of matter

  N. Vogel
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  ABSTRACT: Picosecond laser pulses at a wavelength of 1064 nm have been focused onto a copper cathode in coincidence with an electric field to produce a laser induced breakdown in vacuum and onto anode surface (Ag, Pd, W, AuNi electrodes) for laser-induced discharge in air. At a power density of about 3/spl times/10/sup -13/ W/cm/sup 2/, the formation of local regions with high pressures and temperatures in an electrode gap was investigated. As a result of an intensive energy deposition in a small volume, a strongly coupled microplasma was formed: properties varied during nonstationary processes of heating and hydrodynamic motion over a wide range of the phase diagram, from a Fermi-like to an ideal plasma. As an experimental diagnostic, the authors used laser absorption photography with high temporal (100 ps) and spatial (<1 /spl mu/m) resolution, which allowed us to determinate the spatial-temporal density distribution in the ignition phase of laser-induced discharges, as well as a registration of X-ray radiation by means of picosecond X-ray streak camera. The pulsed bursts of a strongly directed X-ray radiation reveal a nonstationary appearance of extreme states of matter in small localized plasma volume.
  Pulsed Power Conference, 1999. Digest of Technical Papers. 12th IEEE International; 02/1999
• Conference Proceeding: X-ray radiation from cathode spot fragments in low voltage vacuum arcs

  N. Vogel
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  ABSTRACT: Temporal evolution of X-ray emission of laser-induced discharges was investigated by means of a picosecond X-ray streak camera. Point-like structures and thin hot layers of intensive X-ray radiation with life time from 30 ps to 1.5 ns in a spectral range 100 eV-10 keV and hence temperature T&ges;100 eV have been found at first in a comparatively low voltage vacuum discharge (U&ap;150 V-2.7 kV) initiated by picosecond laser beam. The radiation of laser-induced breakdown was investigated just after ignition as well as with a long delay time (up to 20 ns) relative to the ignition point by the laser beam in order to eliminate the X-ray radiation coming from the laser-produced plasma
  Discharges and Electrical Insulation in Vacuum, 1998. Proceedings ISDEIV. XVIIIth International Symposium on; 09/1998
• Article: Plasma parameters within the cathode spot of laser-induced vacuum arcs: experimental and theoretical investigations

  N. Vogel, V.A. Skvortsov
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  ABSTRACT: Cathode spot formation in laser-induced breakdown in vacuum was investigated by laser absorption photography with high spatial (0.5 μm) and temporal (100 ps) resolution. The discharge was initiated between Cu electrodes with a cathode-anode distance of 15-250 μm. The duration of pulsed discharges was 750 ns and dc discharges some milliseconds; the current was below 10 A. Picosecond momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density >5×10²⁶ m^-3 in narrow plasma fragments with a diameter smaller than 5 μm was estimated. Mathematical modeling has satisfactorily explained the formation of the narrow plasma channel due to the bulk current self-focusing, as well as due to the generation of nonstationary emissive centers at the moving boundary of the expanding cathode spot plasma
  IEEE Transactions on Plasma Science 09/1997; · 1.17 Impact Factor
• Conference Proceeding: The dynamic of matter transition into extreme states initiated by high power micro beam of heavy ions

  V. Skvortsov, N. Vogel, A. Lebedev
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  ABSTRACT: This paper deals with numerical investigation of interaction of short pulse (about of 100 ps) intense (with intensities up to 3×10 ¹⁶ W/cm²) micro beams of heavy ions with condensed matter. It had been established, that the extreme states of matter with compression in Gbar pressure range can be produced by the beam-generated strong shock waves. The original scheme of initiation of controlled thermonuclear fusion in micro volume of gold target with D-T mixture is considered where two colliding plasma fluxes (shock waves) are generated using only one ion micro beam
  Discharges and Electrical Insulation in Vacuum, 1996. Proceedings. ISDEIV., XVIIth International Symposium on; 08/1996
• Conference Proceeding: Plasma parameters within the cathode spot of laser-induced vacuumarcs: experimental and theoretical investigations

  N. Vogel, V. Skvortsov
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  ABSTRACT: The cathode spot formation in laser-induced breakdown in a vacuum was investigated by laser absorption photography with high spatial (0.5 μm) and temporal (100 ps) resolution. The discharge was initiated between Cu-electrodes with cathode-anode distance of 25-250 μm. The discharge duration was 750 ns and some milliseconds, the current below 10 A. Picosecond momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density value >5×10²⁶ m^-3 in narrow plasma fragments with diameter smaller than 5 μm was estimated. Principal new physical objects-“shooting solitons”-nonstationary plasma emissive centers, generated at the moving boundary of the expanding cathode spot plasma, obtained during the analysis of computer simulations give a satisfactory explanation of the current transfer in laser-induced breakdown
  Discharges and Electrical Insulation in Vacuum, 1996. Proceedings. ISDEIV., XVIIth International Symposium on; 08/1996
• Article: Measurement of cathode spot parameters with pulsed laser diagnostics

  N. Vogel, J. Heinzinger, F. Cichos
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  ABSTRACT: The cathode spot formation in air within the first 170 ns was investigated by laser absorption photography and ps-pulse interferometry. The discharge was initiated between electrodes made from Ag or Pd with cathode-anode distance below 300 μm, the arc duration was some milliseconds, and the arc current 5-10 A. Picosecond holographic interferometry and momentary absorption photography yielded spatial-temporal density distributions in the ignition phase of the cathode spot. An absolute electron density value on the order of 4×10²⁶ m^-3 has been found. In contrast to vacuum, the cathode spot plasmas broaden little with increasing distance from the cathode, thus narrow plasma channels are observed in the vicinity of the cathode surface having diameters <20 μm
  IEEE Transactions on Plasma Science 01/1996; · 1.17 Impact Factor