共查询到20条相似文献,搜索用时 15 毫秒
1.
T. Döppner S. Teuber Th. Diederich Th. Fennel P. Radcliffe J. Tiggesbäumker K. H. Meiwes-Broer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):157-160
Lead clusters are exposed to strong femtosecond light
pulses. The dependence of the recoil energy on the charge state
of the atomic ion is now investigated using a new detection
setup, i.e., a Thomson
analyser. First results show that in contrast to laser-induced
overdense plasmas at surfaces the recoil energy distribution
appears much narrower. Comparing free lead clusters with lead
clusters embedded in large helium droplets, the charging
dynamics show distinct differences on the femtosecond time
scale. In the embedded case the maximum ionization enhancement
is reached earlier. 相似文献
2.
G. L. Chen H. Y. Lu C. Wang J. S. Liu R. X. Li G. Q. Ni Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):303-307
We propose a plasma channel scheme to obtain an improved
table-top laser driven fusion neutron yield as a result of explosions of
large deuterium clusters irradiated by an intense laser pulse. A cylindrical
plasma channel is created by two moderate intensity laser prepulses at the
edge of a deuterium cluster jet along which an intense main laser pulse
propagates several nanoseconds later. With the aid of this plasma channel,
the main laser pulse will be allowed to deposit its energy into the central
region of the deuterium gas jet where the cluster sizes are larger and the
atomic density is higher. The plasma channel formation and its impact on the
deuterium ion energy spectrum and the consequent fusion neutron yield have
been investigated. The calculated results show that a remarkable increase of
the table-top laser driven fusion neutron yield would be expected. 相似文献
3.
M.A. Lebeault J. Viallon J. Chevaleyre C. Ellert D. Normand M. Schmidt O. Sublemontier C. Guet B. Huber 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):233-242
We exposed small size-controlled lead clusters with a few hundreds of atoms to laser pulses with peak intensities up to 1015 W cm-2 and durations between 60 fs to 2.5 ps. We measured kinetic energies and ionic charge of fragments as a function of the laser
intensity and pulse duration. Highly charged Pbn+ ions up to n = 26 have been detected presenting kinetic energies up to 15 keV. For comparison with our experimental results, we have performed
simulations of the laser coupling with a cluster-sized lead nanoplasma using a qualitative model that was initially proposed
by Ditmire and co-workers at LLNL for the case of rare gas clusters. From these simulations we conclude that two mechanisms
are responsible for the explosion dynamics of small lead clusters. As already observed for large rare gas clusters (n = 106), fragments with charge states below +10 are driven by Coulomb forces, whereas the higher charged fragments are accelerated
by hydrodynamic forces. The latter mechanism is a direct consequence of the strong laser heating of the electron cloud in
the nanoplasma arising from a plasmon-like resonance occurring at n
e = 3n
c. In order to obtain an optimized laser-nanoplasma coupling, our results suggest that the plasma resonance should occur at
the peak intensity of the laser pulse. Due to inertial effects, even for such small-sized clusters, the observed optimum pulse
duration is in the order of 1 ps which is in good agreement with our theoretical results.
Received 18 March 2002 Published online 19 July 2002 相似文献
4.
V. S. Lisitsa A. A. Skovoroda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):571-574
Perspectives of magnetic confinement for the increase of life times of laser
plasmas generated by femtosecond laser pulses are considered. Possibilities
that are provided by miniature magnetic cusp configurations with magnetic
fields of moderate intensities (of order of Teslas) are investigated. The
construction of micro-traps with permanent magnets, making it possible to
increase neutron yield, seems to be very simple and possible for most modern
“table top" laser experiments. 相似文献
5.
A. Heidenreich I. Last J. Jortner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):195-202
We present a theoretical and computational study of the properties and the
response of the nanoplasma and of outer ionization in Xen clusters (n =
55–2171, initial cluster radius R0 = 8.7–31.0 ?) driven by
ultraintense near-infrared laser fields (peak intensity IM = 1015–1020 Wcm-2, temporal pulse length τ= 10–100 fs, and frequency ν= 0.35 fs-1). The positively charged high-energy nanoplasma produced by inner ionization nearly follows the oscillations of
the fs laser pulse and can either be persistent (at lower intensities of IM = 1015–1016 Wcm-2 and/or for larger cluster sizes, where the electron energy distribution is nearly thermal) or transient (at higher intensities
of IM = 1018–1020 Wcm-2 and/or for smaller cluster sizes). The nanoplasma is depleted by outer ionization that was semiquantitatively described by
the cluster barrier suppression electrostatic model, which accounts for the cluster size, laser intensity and pulse length
dependence of the outer ionization yield. The electrostatic model was further utilized for estimates of the laser intensity
and pulse
width dependence of the border radius R0
(I) for the attainment of complete outer ionization at
,
while at R0 > R0
(I) a persistent nanoplasma prevails. R0
(I)
establishes an interrelationship between electron dynamics and nuclear Coulomb explosion dynamics in ultraintense
laser-cluster interactions. 相似文献
6.
S. Borodziuk A. Kasperczuk T. Pisarczyk S. Yu. Gus'kov J. Ullschmied E. Krousky K. Masek M. Pfeifer K. Rohlena J. Skala M. Kalal J. Limpouch P. Pisarczyk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):311-317
Efficiency studies of laser driven thin metal disks
acceleration using the first harmonic (λ1=1.315 μm) of
the Prague Asterix Laser System (PALS) and subsequent craters creation
produced by collisions of these disks with massive targets are presented.
Several different disks made of aluminium and copper foils with diameters of
300 μm and 600 μm and thicknesses of 11 μm (Al) and 3.6 μ
m (Cu) were employed. Disks were placed at the distance of either 100 μ
m or 300 μm in front of aluminium massive targets. The following
irradiation conditions were used: the laser beam energy of 120 J, the focal
spot diameter of 200 μm, and the pulse duration of 0.4 ns (FWHM). A
three-frame interferometric system was employed to determine electron
density distributions in plasma corona. Shape and volume of craters were
obtained by crater replica technology and microscopy measurements. The aim
of these investigations was to analyse conditions leading to the most
effective energy transfer in the process of collision of the accelerated
disks with solid targets. The overall efficiency of these processes was
characterized by the volume of craters produced in such targets. 相似文献
7.
8.
G. Ferrante M. Zarcone S.A. Uryupin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):349-353
Collisionless absorption of linearly polarized electromagnetic wave in a plasma with anisotropic bi-Maxwellian electron velocity
distribution is investigated. Due to the wave magnetic field influence on the electron kinetics in the skin layer, the wave
absorption is found to significantly depend on the degree of the electron temperature anisotropy. Depending on the value of
the skin layer anomaly parameter, and on the electron temperature anisotropy degree, the conditions are found when a significant
decrease or increase of the collisionless absorption is expected.
Received 25 January 2002 相似文献
9.
B. Ziaja A. R.B. de Castro E. Weckert T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):465-480
We apply Boltzmann equations for modelling the radiation damage in samples
irradiated by photons from free electron lasers (FELs). We test this method
in a study case of a spherically symmetric xenon cluster irradiated with
VUV FEL photons. Qualitative agreement between the model predictions and experimental data is found. The results obtained
demonstrate the potential of the Boltzmann method for describing the complex and non-equilibrium dynamics of samples exposed
to FEL radiation. 相似文献
10.
D. Batani F. Strati B. Telaro Th. Löwer T. Hall A. Benuzzi-Mounaix M. Koenig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):99-107
In this paper we describe the quality requirements that a shock wave must fulfil to make equation of state (EOS) measurements
possible: planarity, no-preheating and stationarity of the shock. Experimental measurements have been performed at the Max
Planck Institut für Quantenoptik (Garching). We also present simple analytical models that allow to verify shock stationarity
and absence of preheating.
Received 17 June 2002 Published online 21 January 2003
RID="a"
ID="a"e-mail: batani@mib.infn.it
RID="b"
ID="b"Present address: Pro-beam, Behrinsta?e 6, 85152 Planegg b. München, Germany.
RID="c"
ID="c"UMR 7605 相似文献
11.
Ionization of metal clusters by ions in the Fermi velocity range 总被引:1,自引:0,他引:1
P.G. Reinhard E. Suraud C.A. Ullrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):303-311
We simulate excitation of metal clusters by highly charged, energetic ions, analyzing electron emission in terms of discrete
ionization probabilities. Our test case is the collision of on the cluster at velocities around the electronic Fermi velocity of bulk sodium. The calculations are performed with a density-functional
approach, using the time-dependent local density approximation. We find that ionization takes place on an extremely short
time scale of less than 5 fs. The preferred final charge state depends sensitively on the impact parameter. High ionization
can easily be achieved in sufficiently close collisions. Direct trapping through the by-passing ion is found to be of little
importance at the velocities considered.
Received: 28 July 1997 / Received in final form: 23 December 1997 / Accepted: 8 January 1998 相似文献
12.
W. Kleinig V.O. Nesterenko P.-G. Reinhard Ll. Serra 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):343-352
The systematics of the plasmon response in spherical K, Na and Li clusters in a wide size region is studied. Two simplifying approximations whose validity has been established previously are considered: (a) a separable
approach to the random-phase-approximation, involving an expansion of the residual interaction into a sum of separable terms,
(b) the electron-ion interaction is modeled within the pseudo-Hamiltonian jellium model (PHJM) including nonlocal effects
by means of realistic atomic pseudoHamiltonians. In cases where nonlocal effects turn out to be negligible, the Structure
Averaged Jellium Model (SAJM) has been used. The leading role of Landau damping in forming the plasmon width in medium and
large clusters is demonstrated. Good agreement with available experimental data is achieved for K, Na (using the SAJM) and
small Li clusters (invoking the PHJM). The trends for peak position and width are generally well reproduced, even up to details
of the Landau fragmentation in several clusters. Less good agreement, however, is found for large Li clusters. The possible
reasons of the discrepancy are discussed.
Received: 22 April 1998 / Accepted: 24 July 1998 相似文献
13.
G. Ferrante M. Zarcone S.A. Uryupin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):109-116
The reflection of a test electromagnetic wave normally impinging on a plasma surface is investigated within the formalism
of the surface impedance. The plasma is assumed to possess an anisotropic two-temperature bi-Maxwellian electron velocity
distribution function. The linearly polarized impinging wave during reflection transforms into an elliptically polarized one,
the degree of ellipticity depending on the electron temperature anisotropy. Polarization modifications of the reflected wave
are particularly important in the conditions of the anomalous skin-effect, when the influence of the wave magnetic field on
the electron kinetics in the skin layer is strong. Relations are reported connecting the reflected wave basic parameters to
those of the reflecting plasma surface, making possible, through the experimental determination of the reflected wave characteristics,
to find the plasma electron concentration and the two effective temperatures.
Received 21 May 2002 / Received in final form 21 August 2002 Published online 6 November 2002
RID="a"
ID="a"e-mail: zarcone@unipa.it 相似文献
14.
M. Schnürer S. Ter-Avetisyan H. Stiel U. Vogt W. Radloff M. Kalashnikov W. Sandner P.V. Nickles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):331-335
Using 50 fs ( ∼ 2×1018 W/cm2) and 2 ps ( ∼ 5×1016 W/cm2) pulses from a Ti:Sa multi-TW laser at 800 nm wavelength large Xe-clusters ( 105...106 atoms per cluster) have been excited. Absolute yield measurements of EUV-emission in a wavelength range between 10 nm and
15 nm in combination with cluster target variation were carried out. The ps-laser pulse has resulted in about 30% enhanced
and spatially more uniform EUV-emission compared to fs-laser excitation. Circularly polarized laser light instead of linear
polarization results in enhanced emission which is probably caused by electrons gaining higher energies by the polarization
dependent optical field ionization process. An absolute emission efficiency at 13.4 nm of up to 0.8% in 2π sr and 2.2% bandwidth
has been obtained.
Received 11 January 2001 and Received in final form 27 March 2001 相似文献
15.
K. Shigemori D. Ichinose T. Irifune K. Otani T. Shiota T. Sakaiya H. Azechi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):301-305
We present a novel scheme to measure sound velocity of
shock-compressed iron of geophysical interest. The sound velocity of
laser-irradiated iron foils was obtained with side-on X-ray radiograph
technique from measured rarefaction wave velocity of shocked iron. Iron
foils were irradiated with a two-stepped square laser pulse to reach Earth's
core condition by double compression. The experimental parameters of
temperature and pressure were very close to the Earth's core condition. 相似文献
16.
M. Temporal S. Atzeni D. Batani M. Koenig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(3):509-511
The impedance mismatch effect in a two-layer (low density plastic foam, and solid aluminum, respectively) plane target compressed
by a laser driven shock wave is considered. In such targets the ablative pressure generated by absorption of laser light in
the foam layer is amplified when crossing the foam-aluminum interface. In this paper an analytical model is developed to evaluate
the shock pressure in the aluminum layer as a function of the density and thickness of the foam layer and of the laser parameters.
The model is in good agreement with previously published experimental results [A. Benuzzi et al., Phys. Plasmas 5, 2827 (1998)].
Received 20 January 2000 and Received in final form 16 May 2000 相似文献
17.
T. Mocek B. Rus M. Kozlová J. Polan P. Homer K. Jakubczak M. Stupka D. Snopek J. Nejdl M. H. Edwards D. S. Whittaker G. J. Tallents P. Mistry G. J. Pert N. Booth Z. Zhai M. Fajardo P. Zeitoun J. Chalupsky V. Hájková L. Juha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):439-444
An overview of recent advances in applications of currently the most energetic X-ray laser at 21 nm is given. The unique parameters
of this half-cavity based X-ray laser such as record output energy of 10 mJ, highly symmetric beam, robustness and reproducibility,
have made it possible to carry out a number of multidisciplinary scientific projects featuring novel applications of intense
coherent X-ray radiation. Selected results obtained in these experiments are reviewed, including X-ray laser probing of dense
plasmas, measurements of transmission of focused soft X-ray radiation at intensities of up to 1012 W cm-2, measurements of infrared laser ablation rates of thin foils, and ablative microstructuring of solids. 相似文献
18.
D. Batani C. Bleu Th. Löwer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(2):231-243
In this paper we analyze the use of phase plates to obtain homogeneous laser intensity profiles. We studied the dependence
of intensity distribution on phase plates characteristics, we obtained analytical solution for the intensity profile in the
focal plane for plane waves and developed a numerical simulator to calculate the intensity distribution with a generic initial
beam and at any propagation plane. We defined criteria to evaluate the quality of profiles produced by different phase plates.
Finally we compared experimental results obtained at the Max-Planck Institut für Quantenoptik of Garching with our numerical
simulations.
Received 23 July 2001 and Received in final form 8 January 2002 相似文献
19.
D. Batani C. Botto M. Moret M. Milani G. Lucchini K. Eidmann F. Cotelli C. Lora Lamia Donin G. Poletti T. Ford A. Stead 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):167-179
In this paper the results of an experiment on soft X-ray contact microscopy using a laser-plasma source are presented. A resolution
of 50 nm has been achieved imaging pig sperm cells, while other specimens, such as algae and yeast cells, showed internal
details, proving the technique to be a powerful tool for biological investigations. Original biological information has been
obtained and the conditions for optimal image formation have been studied.
Received 5 June 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: batani@mib.infn.it 相似文献
20.
C. Kohl S.M. El-Gammal F. Calvayrac E. Suraud P.-G. Reinhard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):271-274
We investigate spin modes in the ground state and the polarized first isomer of the Na12 cluster describing the valence electrons in time-dependent local-spin-density approximation (TDLSDA) and the detailed ionic
background using local pseudopotentials. The spin modes show a collective redshift compared to the unperturbed particle-hole
excitations. They are strongly fragmented and the average energy of the modes along the principal axes are related to the
underlying geometry (triaxial or axially symmetric). For the polarized isomer, we find significant cross talk between the
spin modes and the dipole plasmon, which hints at a possible spectroscopic identification.
Received: 22 June 1998 / Accepted: 29 July 1998 相似文献