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Title: Characteristics of Neutron Pulses at PF- 1000

Abstract

The energy of neutrons and time of their generation are determined from seven scintillation detectors positioned in the axial direction. At the onset, each neutron pulse has beam-target origin with downstream energies in range of 2.7-3.2 MeV. The final part of neutrons has isotropic energy distribution with energies up to 2.6-2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the axis layer of the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with the structure of the dense plasma at the bottom of the dilating current sheath, similarly to the first pulse. The possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed.

Authors:
; ; ;  [1]; ; ; ; ; ;  [2]; ;  [3];  [4]
  1. CTU Prague, Technicka 2, 166 27 Prague (Czech Republic)
  2. Institute of Plasma Physics and Laser Microfusion, 23 Hery, 00-908 Warsaw (Poland)
  3. A. Soltan Institute forf Nuclear Studies, 05-400 Otwock-Swierk n. Warsaw (Poland)
  4. ICDMP, 23 Hery, 00-908 Warsaw (Poland)
Publication Date:
OSTI Identifier:
20729247
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 808; Journal Issue: 1; Conference: 6. international conference on dense Z-pinches, Oxford (United Kingdom), 25-28 Jul 2005; Other Information: DOI: 10.1063/1.2159351; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; DEUTERONS; ELECTRIC CURRENTS; ENERGY SPECTRA; LAYERS; LONGITUDINAL PINCH; MEV RANGE; NEUTRONS; PLASMA; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA HEATING; PLASMA SHEATH; PULSES; SCINTILLATION COUNTERS

Citation Formats

Kubes, P., Kravarik, J., Barvir, P., Klir, D., Scholz, M., Paduch, M., Tomaszewski, K., Ivanova-Stanik, I., Bienkowska, B., Karpinski, L., Sadowski, M.J., Skladnik-Sadowska, E., and Schmidt, H.. Characteristics of Neutron Pulses at PF- 1000. United States: N. p., 2006. Web. doi:10.1063/1.2159351.
Kubes, P., Kravarik, J., Barvir, P., Klir, D., Scholz, M., Paduch, M., Tomaszewski, K., Ivanova-Stanik, I., Bienkowska, B., Karpinski, L., Sadowski, M.J., Skladnik-Sadowska, E., & Schmidt, H.. Characteristics of Neutron Pulses at PF- 1000. United States. doi:10.1063/1.2159351.
Kubes, P., Kravarik, J., Barvir, P., Klir, D., Scholz, M., Paduch, M., Tomaszewski, K., Ivanova-Stanik, I., Bienkowska, B., Karpinski, L., Sadowski, M.J., Skladnik-Sadowska, E., and Schmidt, H.. Thu . "Characteristics of Neutron Pulses at PF- 1000". United States. doi:10.1063/1.2159351.
@article{osti_20729247,
title = {Characteristics of Neutron Pulses at PF- 1000},
author = {Kubes, P. and Kravarik, J. and Barvir, P. and Klir, D. and Scholz, M. and Paduch, M. and Tomaszewski, K. and Ivanova-Stanik, I. and Bienkowska, B. and Karpinski, L. and Sadowski, M.J. and Skladnik-Sadowska, E. and Schmidt, H.},
abstractNote = {The energy of neutrons and time of their generation are determined from seven scintillation detectors positioned in the axial direction. At the onset, each neutron pulse has beam-target origin with downstream energies in range of 2.7-3.2 MeV. The final part of neutrons has isotropic energy distribution with energies up to 2.6-2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the axis layer of the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with the structure of the dense plasma at the bottom of the dilating current sheath, similarly to the first pulse. The possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed.},
doi = {10.1063/1.2159351},
journal = {AIP Conference Proceedings},
number = 1,
volume = 808,
place = {United States},
year = {Thu Jan 05 00:00:00 EST 2006},
month = {Thu Jan 05 00:00:00 EST 2006}
}
  • The paper reports on spectroscopic studies of high-current plasma discharges performed at different gas fillings within the large PF-1000 facility. To study visible radiation (VR) the use was made of a MECHELLE registered 900-spectrometer equipped with the CCD readout. The observations of a PF pinch column were performed at an angle of about 65 deg. to the z-axis, and the viewing field was at a distance of 40-50 mm from the electrode ends. Optical measurements were carried out at 0.5-{mu}s exposition synchronized with a chosen period of the investigated discharge. Differences in the optical spectra, recorded at various deuterium-helium mixtures,more » were analyzed. Intensities of HeI lines were computed for an assumed electron temperature and compared with the experiment. Estimated plasma concentration in pure-deuterium discharges amounted to 8x1018 cm-3, while that in pure helium shots was (4-7)x1017 cm-3 only. Estimates of the electron temperature, from the ratio of intensities of the chosen spectral lines and the continuum, gave values ranging from 5 eV to 50 eV. The paper presents also some spectra from 'weak shots', which show distinct impurity lines caused by different reasons.« less
  • At the signals of x-rays usually 2 peaks were observed. The first peak corresponded to the time of the minimum diameter of the imploding plasma sheath (pinch phase) recorded by the visible frames. The second peak occurred 150-200 ns later at the time of the development of instabilities. High-energy electrons registered in the upstream and downstream directions differed in the intensity (ratio 3:1) and in the time of production. Their peaks correlated with x-rays. The energy of neutrons and time of their generation were determined by time-of-flight method from the pulses of seven scintillation detectors positioned in the axial direction.more » At the rise-time, each neutron pulse has registered downstream energies in range of 2.7-3.2 MeV. The final part of neutron pulse has isotropic energy distribution with energies up to 2.6-2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the dense plasma in the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with existence of the structure of the dense plasma positioned at the bottom of the dilating current sheath, similarly to the first pulse. The neutrons have a non-thermal beam-target origin. A possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed.« less
  • The main stages of the plasma current sheath (PCS) dynamics on two plasma focus (PF) facilities with different geometries of the electrode system, PF-3 (Filippov type) and PF-1000 (Mather type), were studied by analyzing the results of the current and voltage measurements. Some dynamic characteristics, such as the PCS velocity in the acceleration phase in the Mather-type facility (PF-1000), the moment at which the PCS reaches the anode end, and the plasma velocity in the radial stage of plasma compression in the PF-3 Filippov-type facility, were determined from the time dependence of the inductance of the discharge circuit with amore » dynamic plasma load. The energy characteristics of the discharge circuit of the compressing PCS were studied for different working gases (deuterium, argon, and neon) at initial pressures of 1.5–3 Torr in discharges with energies of 0.3–0.6 MJ. In experiments with deuterium, correlation between the neutron yield and the electromagnetic energy deposited directly in the compressed PCS was investigated.« less
  • The paper reports on spectroscopic studies of the interaction of high-current Plasma-Focus (PF) discharges with a CD2 100-{mu}m-fiber within the PF-1000 facility operated at 600-650 kJ. Visible radiation (VR) spectra were recorded with a MECHELLE registered 900 spectrometer at different instants. The exposition was varied from 100 ns to 200 {mu}s. Hydrogen- or deuterium- and carbon-ion-lines were identified. The electron concentration of the core, as estimated from the Stark broadening of the CII-CIV lines, was above 1019 cm-13. From the intensity ratio of carbon-ion lines (CIII/CII and CIV/CIII) it was estimated that the electron temperature of the core was abovemore » 5 eV. For deuterium shots it was observed that the CD2-fiber induced a decrease in the neutron yield (to about 1010), but the obtained spectroscopic data are of interest for understanding of the physical processes.« less