共查询到20条相似文献,搜索用时 15 毫秒
1.
M. Sharif S. Hussain M. Zakaullah A. Waheed 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):337-341
A 1.8 kJ Mather-type plasma focus (PF) for argon and hydrogen
filling is examined. Two anode configurations are used. One is tapered
towards the anode face, and the other is cylindrical but the face is cut at
different angles. At optimum conditions, the system is found to emit Cu–Kα
X-rays of about 1.6±0.1 J/sr in the side-on direction for argon
filling, which
is about 32% of the total X-ray emission. In 4π-geometry, maximum
total X-ray
yield and wall plug efficiency found are 26.4±1.3 J and 1.5±
0.1%
respectively. The modified geometry may help to use the PF as a radiation
source for X-ray diffraction. 相似文献
2.
G. Tomassetti A. Ritucci A. Reale L. Palladino L. Reale S. V. Kukhlevsky F. Flora L. Mezi J. Kaiser A. Faenov T. Pikuz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):73-77
A capillary discharge soft X-ray laser operating at 46.9 nm on the transition 3p-3s (J = 0-1) of the Ne-like Ar has been realized by exciting the active medium with a long half-cycle duration current pulse of
140 ns. The current is produced by discharging a 10 nF water dielectric capacitor, initially charged to voltages lower than
200 kV by a six stage Marx generator, through a 15-cm long capillary channels. The laser amplification has been obtained by
properly adjusting all the other experimental parameters. Utilizing a 3-mm in diameter Al2O3 capillary channel initially filled with 0.3 torr of Ar pressure, a laser beam, which has a 4-mrad divergence and a time duration
of 1.3 ns, is characterized by a gain of 0.6±0.1 cm-1. The stability of the plasma compression followed by the laser emission is verified.
Received 13 December 2001 相似文献
3.
S. I. Tkachenko V. M. Romanova A. R. Mingaleev A. E. Ter-Oganesyan T. A. Shelkovenko S. A. Pikuz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):335-341
Experimental results on electrical explosion of wires in vacuum with current density A/m2, current rise rate (dI/dt) ~ 50 A/ns and current pulse with amplitude ∼10 kA are presented. The structure of the discharge
channels in vacuum has been studied using laser shadow and schlieren imaging with 7 ns frames, UV pinhole images with 5 ns
frames and X pinch X-ray backlighting. The information on the dense core material and the conducting plasma distributions
was obtained in our experiments by analyzing and comparing the results obtained from all diagnostics. 相似文献
4.
A. A. Akunets S. S. Anan’ev Yu. L. Bakshaev P. I. Blinov V. A. Bryzgunov A. S. Chernenko S. A. Dan’ko E. D. Kazakov V. D. Korolev B. R. Meshcherov S. L. Nedoseev V. G. Pimenov E. A. Smirnova G. I. Ustroev V. V. Vikhrev I. V. Volobuyev A. A. Zelenin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):499-502
On the S-300 installation at currents up to 2 MA with rise time 100 ns, the investigation of the formation process of high-temperature
plasma in fast Z-pinch was carried out. The central part of the loads was made from agar-agar and represented a deuterated
polyethylene cylinder with small density 50 and 75 mg/sm3 and 1–2 mm diameter. On the ICT images, obtained in optical and soft X-ray range of a spectrum with 3–5 ns exposition, it
is visible that on the axis of the polyethylene cylinder at the current`s rise time a cord is formed and it is separated into
bright formations. They were observed on a background of a luminous area which occupied the initial neck volume. On time-integrated
pinhole pictures obtained in SXR range (E > 1–4 keV), hot points with minimal size of 50 microns were registered. From the
chronograms results, obtained by means of the optical high-speed-streak camera mount along the neck axis with time resolution
< 1 ns, it follows that luminous formations arise sequentially during the different time moments (in 10–30 ns). Occurrence
of luminous formations was accompanied by X-ray radiation occurrence with energy E > 1 keV with short duration of 2–4 ns.
Simultaneously with X-ray radiation neutrons with the maximal yield of 4.5×109 were registered. The average energy measured in 4 directions under angles with an axis of: 0○ (above the anode), 90○, 180○ (under the cathode) and 270○, were accordingly: 2.4±0.2, 2.5±0.1, 2.5±0.1, 2.5±0.1 MeV. 相似文献
5.
6.
L. I. Ivanov A. I. Dedyurin I. V. Borovitskaya O. N. Krokhin V. Y. Nikulin E. N. Peregudova A. V. Oginov A. A. Tikhomirov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):149-152
The work presents the experimental results of investigation of the possibility of the creating of high adhesive compound of
chemically noninteracting metals by means of pulse streams of high temperature dense plasma. The 4 kJ plasma focus installation
was used as a source of pulse streams of plasma. In the experiment assemblies of Cu–W and Pb–Fe samples were used. The deep
penetration of atoms Cu and Pb accordingly in W and Fe was found. The mechanisms of the penetration of chemically neutral
atoms into a material of the target can be connected with the following processes: the energy transfer from plasma pulse to
implanting atoms, the origin and distribution of shock waves in the material of a target, and also the Rayleigh-Taylor instability
of the border of two combining materials. 相似文献
7.
L. Karpinski M. Scholz J.G. Linhart A. Szydlowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(2):255-259
This paper describes experiments on foam liners performed with the PF-1000 plasma focus facility. A streak camera has been
used to observe interaction of a hydrogen plasma current sheath with a cylindrical foam target. It is shown that a thin foam
liner can be uniformly imploded by a plasma focus current sheath.
Received: 11 February 1999 / Received in final form: 30 March 1999 相似文献
8.
Y. P. Zhao Y. Xie Q. Wang T. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(3):379-382
With pure Ar and gaseous mixtures of Ar-He, the laser spike of Ne-like Ar 46.9 nm pumped by capillary discharge is measured
with XRD (X-ray diode) at low pressure. We observe the effects of the Ar pressure and the He ratio on the amplitude of laser
pulse. Compared with the laser spike of pure Ar, a mixture of Ar and a small quantity of He enhances the laser output. The
time of lasing onset and the duration of laser pulses are not affected by mixing He. In addition, a monochromator is used
to measure the laser pulse at 46.9 nm. This is the first observation of laser output with a Ar-He mixture. 相似文献
9.
P. Vrba M. Vrbova N. A. Bobrova P. V. Sasorov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):481-486
Pinching discharge in non-ablative and ablative capillaries filled by boron vapors is studied. The aim is to find out conditions
for lasing at Balmer alpha transition of hydrogen-like boron ions B4+ (λ= 26.23 nm). The primary pumping process under consideration is a three-body collisional recombination, which takes place
in non-stationary underheated plasma during the pinch expansion stage. The results of Z-pinch computer modeling including
the plasma kinetics and gain evaluation are compared for two different quarter periods of electrical current passing through
the capillary. 相似文献
10.
K. Quinn P. A. Wilson B. Ramakrishna G. Sarri L. Romagnani A. Pipahl O. Willi L. Lancia J. Fuchs D. C. Carroll M. N. Quinn P. Gallegos X. H. Yuan P. McKenna R. J. Clarke D. Neely M. Notley A. Macchi M. Borghesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):293-297
New method of neutron spectrum recovery described in the paper involves accelerated deuterons (that produce neutrons in DD
reaction) and allows getting neutron spectrum in any direction from computed time-velocity characteristics of deuterons. Time of flight signals registered in various distances and directions are used, that makes
information involved in the recovery process (Monte-Carlo simulation) more complete than in a one-directional case, although
additional assumption about axial symmetry of deuterons motion, is required. In the paper recent results of two standard tests
of the proposed method are presented demonstrating its capability to recover neutron spectrum from time-of-flight signals. 相似文献
11.
C. Lao J. Cotrino A. Palmero A. Gamero A.R. González-Elipe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):361-366
The main objective of this work is to obtain the electron temperature in an argon surface-wave-produced plasma column at intermediate
gas pressures. After proving that argon upper excited states remain in Excitation Saturation Balance, the value of electron
temperature along the plasma column has been obtained using a modified Saha equation and a corrected Boltzmann-plot. Moreover,
the electron energy distribution function has been verified to be nearly Maxwellian in a 0.8-2.8 torr intermediate pressure
range.
Received 24 July 2000 and Received in final form 19 January 2001 相似文献
12.
N.L. Tsintsadze P.K. Shukla L. Stenflo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):109-115
The electroweak coupling between intense neutrino beams and strongly degenerate relativistic dense electron-positron magnetoplasmas
is considered. The intense neutrino bursts interact with the plasma due to the weak Fermi interaction force, and their dynamics
is governed by a kinetic equation. Our objective here is to develop a kinetic equation for a degenerate neutrino gas and to
use that equation to derive relativistic magnetohydrodynamic equations. The latter are useful for studying numerous collective
processes when intense neutrino beams nonlinearly interact with degenerate, relativistic, dense electron-positron plasmas
in strong magnetic fields. If the number densities of the plasma particles are of the order of 1033 cm-3, the pair plasma becomes ultra-relativistic, which strongly affects the potential energy of the weak Fermi interaction. The
new system of equations allows several neutrino-driven streaming instabilities involving new types of relativistic Alfvén-like
waves. The relevance of our investigation to the early universe and supernova explosions is discussed.
Received 11 September 2002 Published online 4 February 2003
RID="a"
ID="a"Permanent address: Department of Physics, Tbilisi State University, Chavchavadze 3, Tbilisi 38028, Georgia.
RID="b"
ID="b"Also at the Department of Plasma Physics, Ume? University, 90187 Ume?, Sweden; and the Center for Interdisciplinary Plasma Science,
Max-Planck Institut für Plasmaphysik und extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany. e-mail: ps@tp4.ruhr-uni-bochum.de
RID="c"
ID="c"Permanent address: Department of Plasma Physics, Ume?University, 90187 Ume?, Sweden. 相似文献
13.
An ingenious method for fabricating network of polyaniline nanowires at room temperature in microsecond timescale is demonstrated by using the pulsed electron beam of a plasma focus device. The electron beam of the plasma focus device having a wide range of energies (10-200 keV) was irradiated on to the freestanding polyaniline film. The growth of polyaniline nanowires on the surface of film sample is confirmed by field emission scanning electron microscope images showing nanowires of about 50-80 nm in diameter and up to few tens of micrometers in length. 相似文献
14.
H. Toki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):177-180
We critically review the present relativistic mean-field theory from the viewpoint of missing pions. We introduce the interesting
experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear
surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin
response functions and others. The radioactive ion beams are the tools of studying the unstable nuclei, which have extended
nuclear surfaces. We shall start with radioactive ion beams the nuclear surface science, which includes the surface pion condensation
as the important ingredient in addition to spin-orbit splitting and surface pairing.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
15.
V. Milosavljević S. Djeniže 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):385-390
On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low-pressure, pulsed
arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent
agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation
for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and N) are not possible. Besides, on the basis of the observed asymmetry of the Stark broadened line profile we have obtained its
ion broadening parameter (A) caused by influence of the ion microfield to the line broadening mechanism and also the influence of the ion dynamic effect
(D) to the line shape. Our A and D parameters represent the first data obtained experimentally using the line profile deconvolution procedure. We have found
stronger influence of the ion contribution to the 706.52 nm He I line profile than the existing theoretical approximations
estimate. This can be important for plasma modeling or for diagnostics.
Received 30 October 2002 Published online 15 April 2003
RID="a"
ID="a"e-mail: vladimir@ff.bg.ac.yu 相似文献
16.
E. Arrigoni G.C. Strinati 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):433-448
We study the zero-temperature spin fluctuations of a two-dimensional itinerant-electron system with an incommensurate magnetic
ground state described by a single-band Hubbard Hamiltonian. We introduce the (broken-symmetry) magnetic phase at the mean-field
(Hartree-Fock) level through a spiral spin configuration with characteristic wave vector Q different in general from the antiferromagnetic wave vector Q
AF, and consider spin fluctuations over and above it within the electronic random-phase (RPA) approximation. We obtain a closed system of equations for the generalized wave vector and frequency dependent susceptibilities, which are equivalent to the
ones reported recently by Brenig. We obtain, in addition, analytic results for the spin-wave dispersion relation in the strong-coupling
limit of the Hubbard Hamiltonian and find that at finite doping the spin-wave dispersion relation has a hybrid form between that associated with the (localized) Heisenberg model and that associated with the (long-range) RKKY exchange interaction.
We also find an instability of the spin-wave spectrum in a finite region about the center of the Brillouin zone, which signals
a physical instability toward a different spin- or, possibly, charge-ordered phase, as, for example, the stripe structures
observed in the high-T
c materials. We expect, however, on physical grounds that for wave vectors external to this region the spin-wave spectrum that
we have determined should survive consideration of more sophisticated mean-field solutions.
Received 15 September 2000 相似文献
17.
R.L. Leheny Y.S. Lee G. Shirane R.J. Birgeneau 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):287-290
Inelastic neutron scattering with high wave-vector resolution has characterized the propagation of transverse spin wave modes
near the antiferromagnetic zone center in the metastable domain state of a random field Ising magnet. A well-defined, long
wavelength excitation is observed despite the absence of long-range magnetic order. Direct comparisons with the spin wave
dispersion in the long-range ordered antiferromagnetic state reveal no measurable effects from the domain structure. This
result recalls analogous behavior in thermally disordered anisotropic spin chains but contrasts sharply with that of the phonon
modes in relaxor ferroelectrics.
Received 2 November 2002 / Received in final form 4 February 2003 Published online 11 April 2003
RID="a"
ID="a"leheny@pha.jhu.edu 相似文献
18.
J. ?ech P. S?ahel Z. Navrátil 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):259-264
In this work we have studied the influence of electrode gap width (inter-electrode distance) on plasma properties of the diffuse
coplanar surface barrier discharge. The outer conditions and discharge configuration can substantially influence properties
of the discharge. Better understanding of these effects can lead to optimization of the discharge parameters for industrial
applications. In this work the discharge was operated in nitrogen at atmospheric pressure. The electrode gap width was varied
in the range from 0.6 to 2.2 mm. The input voltage, electrode temperature and gas flow was kept constant for all cases. Plasma
parameters were studied by the means of time and space resolved optical emission spectroscopy and oscilloscopic measurements.
These measurements gave us time and space distribution of discharge luminosity (e.g. intensities of second positive and first
negative systems of nitrogen) and 1D-spatial profiles of rotational and vibrational temperature of nitrogen. 相似文献
19.
F. S. Krasniqi O. Renner E. Dalimier E. Dufour R. Schott E. Förster 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):439-444
A systematic study of the Langmuir-wave-caused dips (L
dips) observed in profiles of the Al Ly γ line emitted from
laser irradiated sandwich targets indicates that these fine
spectral features can be used as a tool for density diagnostics in
intermediately coupled plasmas. The spectroscopic data required
for a reliable identification of L dips were collected by a
vertical-geometry Johann spectrometer providing high spectral and
spatial resolution. The electron densities deduced from the
evolution of the L dips along the laser target axis compare well
with those derived from hydrosimulations and from measurements of
the line widths and shifts. 相似文献
20.
L. Torrisi A. Borrielli D. Margarone F. Caridi A. M. Mezzasalma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):343-348
A pulsed Nd:Yag laser, at intensities of the order of 1010 W/cm2, is employed to irradiate different thick metallic targets (Ti, Fe, Ag, and Ni) placed in vacuum. The obtained non-equilibrium
plasmas are investigated with various analytical techniques. An electrostatic ion energy analyzer and different ion collectors
are employed to monitor in situ the ions ejected from the plasma and to determine the core plasma temperature, the ion energy
distributions and the ion angular emission. An optical spectrometer is employed to analyze the plasma corona emitted light
vs. wavelength and to identify the emitted characteristic lines. The optical spectroscopy permitted to evaluate the electron
temperatures and densities. Results show strong temperature and density gradients occurring in the laser-generated plasma
plume. 相似文献