共查询到20条相似文献,搜索用时 15 毫秒
1.
K. Mima K. A. Tanaka R. Kodama T. Johzaki H. Nagatomo H. Shiraga N. Miyanaga M. Murakami H. Azechi M. Nakai T. Norimatu K. Nagai T. Taguchi H. Sakagami 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):259-264
Reviewed are the present status of the fast ignition researches. Since
1997, the fast ignition experiment and theory researches have been
extensively continued at the Institute of Laser Engineering of Osaka
University. In particular, the cone-shell target experiments and simulation
research have been progressing. In order to demonstrate heating of imploded
high density plasma to the ignition temperature, in the April of 2003, the
construction of heating laser of 10 kJ/10 ps/1.06 μm (Laser for Fusion
Experiment; LFEX), for FIREX-I (Fast Ignition Realization Experiment) has
started. The fabrication of DT foam cryogenic cone target is also under
development as a collaboration program between Osaka University and NIFS (National Institute for Fusion Science). The LFEX
will be completed in 2008.
After the completion of LFEX, the foam cryogenic cone shell target
experiment will start in 2008. As a new approach toward a compact ignition,
an impact fusion has been proposed, where the ablative acceleration to the
order of 108 cm/s is the key issue. The ablation acceleration related
to the impact fusion has been explored by experiments. 相似文献
2.
D. V. Il’in S. Yu. Gus’kov N. V. Zmitrenko A. A. Levkovskii V. B. Rozanov V. E. Sherman 《Journal of Russian Laser Research》2008,29(6):581-586
The fast ignition as, possibly the most efficient method of inertial confinement fusion (ICF) is based on heating a small
fusion initiation region (igniter) while the rest of the target is compressed by a compressing driver. We investigate the
influence of two factors on the efficiency of fast ignition of ICF-targets. The first factor is the spatial distribution of
thermonuclear-fuel parameters formed due to the ICF-target irradiation by the compressing driver. The second one is a mismatch
in the time moments of the target maximum compression and the igniter heating by the igniting driver. The main characteristics
of fast ignition, namely, the minimum energy of igniter needed to ignite the main ICF-target fuel (ignition energy) and the
burn efficiency (ratio between the burnt and initial fuel masses), are investigated in view of numerical simulation. The scale-invariant
dependences of the minimum ignition energy E
ig and the burn efficiency are obtained. It is shown that the burn efficiency depends on the spatial heterogeneity of the thermonuclear-fuel
parameters much weaker then the ignition energy, but a strong dependence of the burn efficiency on the mismatch in time moments
of the maximum compression and ignition is found. In particular, the ignition before the time moment of the maximum compression
is more favorable than the ignition at just this moment. 相似文献
3.
S. W. Haan M. C. Herrmann J. D. Salmonson P. A. Amendt D. A. Callahan T. R. Dittrich M. J. Edwards O. S. Jones M. M. Marinak D. H. Munro S. M. Pollaine B. K. Spears L. J. Suter 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):249-258
Targets intended to produce ignition on NIF are being simulated and the simulations are used to set specifications for target
fabrication and other program elements. Recent design work has focused on designs that assume only 1.0 MJ of laser energy
instead of the previous 1.6 MJ. To perform with less laser energy, the hohlraum has been redesigned to be more efficient than
previously, and the capsules are slightly smaller. Three hohlraum designs are being examined: gas fill, SiO2 foam fill, and SiO2 lined. All have a cocktail wall, and shields mounted between the capsule and the laser entrance holes. Two capsule designs
are being considered. One has a graded doped Be(Cu) ablator, and the other graded doped CH(Ge). Both can perform acceptably
with recently demonstrated ice layer quality, and with recently demonstrated outer surface roughness. Complete tables of specifications
are being prepared for both targets, to be completed this fiscal year. All the specifications are being rolled together into
an error budget indicating adequate margin for ignition with the new designs. The dominant source of error is hohlraum asymmetry
at intermediate modes 4–8, indicating the importance of experimental techniques to measure and control this asymmetry. 相似文献
4.
S. Yu. Gus’kov N. N. Demchenko N. V. Zmitrenko P. A. Kuchugov V. B. Rozanov R. V. Stepanov R. A. Yakhin 《JETP Letters》2017,105(6):402-407
It is shown that fast ignition can ensure the combustion of asymmetrically compressed targets for inertial confinement fusion with an efficiency close to the combustion of one-dimensionally compressed targets. This statement is valid not only for targets specially designed for fast ignition. Fast heating by an external energy source can ensure the ignition of a target designed for spark ignition, but where this ignition does not occur because inhomogeneities are formed in the temperature and density distributions owing to the development of hydrodynamic instabilities. The condition for ignition is the fast heating of the plasma in the combustion initiation region whose size is comparable with the sizes of compression inhomogeneities. Thus, fast ignition not only significantly reduces the ignition energy, but also is possibly a necessary stage in the inertial confinement fusion scheme when the spherically symmetric compression of a target requires very high engineering and financial expenses. The studies are based on the numerical simulation of the compression and combustion of inertial confinement fusion targets with one- and two-dimensional hydrodynamic codes. 相似文献
5.
Progress in direct-drive inertial confinement fusion research at the
laboratory for laser energetics
R. L. McCrory D. D. Meyerhofer S. J. Loucks S. Skupsky R. Betti T. R. Boehly T. J.B. Collins R. S. Craxton J. A. Delettrez D. H. Edgell R. Epstein K. A. Fletcher C. Freeman J. A. Frenje V. Yu. Glebov V. N. Goncharov D. R. Harding I. V. Igumenshchev R. L. Keck J. D. Kilkenny J. P. Knauer C. K. Li J. Marciante J. A. Marozas F. J. Marshall A. V. Maximov P. W. McKenty S. F.B. Morse J. Myatt S. Padalino R. D. Petrasso P. B. Radha S. P. Regan T. C. Sangster F. H. Séguin W. Seka V. A. Smalyuk J. M. Soures C. Stoeckl B. Yaakobi J. D. Zuegel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):233-238
Direct-drive inertial confinement fusion (ICF) is
expected to demonstrate high gain on the National Ignition Facility (NIF) in
the next decade and is a leading candidate for inertial fusion energy
production. The demonstration of high areal densities in hydrodynamically
scaled cryogenic DT or D2 implosions with neutron yields that are a
significant fraction of the “clean” 1-D predictions will validate the
ignition-equivalent direct-drive target performance on the OMEGA laser at
the Laboratory for Laser Energetics (LLE). This paper highlights the
recent experimental and theoretical progress leading toward achieving this
validation in the next few years.
The NIF will initially be configured for X-ray drive and with no beams
placed at the target equator to provide a symmetric irradiation of a
direct-drive capsule. LLE is developing the “polar-direct-drive” (PDD)
approach that repoints beams toward the target equator. Initial 2-D
simulations have shown ignition. A unique “Saturn-like” plastic ring
around the equator refracts the laser light incident near the equator toward
the target, improving the drive uniformity.
LLE is currently constructing the multibeam, 2.6-kJ/beam, petawatt laser
system OMEGA EP. Integrated fast-ignition experiments, combining the OMEGA
EP and OMEGA Laser Systems, will begin in FY08. 相似文献
6.
P. A. Holstein M. Casanova A. Casner C. Cherfils E. Dattolo L. Disdier D. Galmiche J. Giorla M. Houry J. P. Jadaud S. Laffite S. Liberatore P. Loiseau L. Lours L. Masse M. C. Monteil O. Morice M. Naudy F. Philippe F. Poggi F. Renaud G. Riazuelo Y. Saillard P. Seytor M. Vandenboomgaerde F. Wagon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):239-247
This article sums up the theoretical and experimental studies about
ignition. Three experiments are salient this year on the Omega laser in
collaboration with DOE laboratories (1) 3 cones of beams allow to mimic the
LMJ configuration and to get symmetry measurements. (2) We measured
perturbations due to hydro-instability in CHGe planar samples with face-on
and side-on radiographs. (3) We improved our nuclear diagnostics,
particularly the neutron image system tested on direct drive implosions. As far as LMJ target design is concerned, we defined
a preliminary domain
corresponding to the possible operation at 2ω. At 3ω we studied the low mode
instability effects on the DT deformation (due to the laser or to the
target) and on the yield. The stability is clearly improved with graded
doped CH for our nominal capsule L1215. 相似文献
7.
Summary Through numerical simulations, a target has been designed to produce, when irradiated with the appropriate heavy-ion beam,
an energy gain close to 100. The thermofluid numerical studies for the dynamical behaviour of this target, made with the 1D
code CLIFF and with the 2D code COBI-1, have shown some interesting features: the fusion fuel ignites almost contemporaneously
and ignition occurs only for asymmetries in the beam intensity between pole and equator of less than 6%. Radiation losses
play an important role when asymmetries are present. Actually, when radiation transfer is switched-off in the code, ignition
has been observed even for asymmetries of 10%.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
8.
A general concept of fast ignition by a hydrodynamic pulse is developed. The main statements of the concept are formulated
having in mind the need to ignite the pre-compressed thermonuclear fuel of the inertial confinement fusion (ICF) target. Initially,
combustion must be initiated inside the hydrodynamic flow during its action on the target. The conditions for propagating
a self-sustaining thermonuclear-detonation wave from an igniter on the thermonuclear fuel of the ICF-target must be provided.
For this, the deuterium–tritium (DT) igniter placed in the forward part of the hydrodynamic flow should not only be heated
up to thermonuclear temperature, but also compressed to a density close to the density of the ICF-target fuel. It is shown
that the detonation of the multilayer conical target (containing DT-ice and a heavy pusher) enables fast ignition of the ICF
target fuel of 200–500 g/cm3 density at an implosion velocity of 300–500 km/s. 相似文献
9.
在局域热动平衡近似下, 利用能量平衡关系, 建立热核系统整体点火能量平衡方程, 对该方程求解得到热核反应系统点火阈值. 在计算和分析的基础上给出参数空间的点火关系, 以及该条件受装量、核子数比以及返照率等因素的影响情况. 点火时刻面密度越大, 则对应的点火温度越低, 并且电子-辐射温度脱离越小, 越接近三温平衡的点火状态; 反之则在点火时刻对应较大温度脱离. 更重要的是, 该分析方法还可以根据点火时刻系统的物理状态, 通过线性稳定性分析方法, 描述出系统的后续行为, 也就是说, 可以判断出这样的热核系统能否继续升温并实现深度燃烧. 相似文献
10.
Lei AL Tanaka KA Kodama R Kumar GR Nagai K Norimatsu T Yabuuchi T Mima K 《Physical review letters》2006,96(25):255006
We propose a foam cone-in-shell target design aiming at optimum hot electron production for the fast ignition. A thin low-density foam is proposed to cover the inner tip of a gold cone inserted in a fuel shell. An intense laser is then focused on the foam to generate hot electrons for the fast ignition. Element experiments demonstrate increased laser energy coupling efficiency into hot electrons without increasing the electron temperature and beam divergence with foam coated targets in comparison with solid targets. This may enhance the laser energy deposition in the compressed fuel plasma. 相似文献
11.
A. A. Andreev S. Yu. Gus’kov D. V. Il’in A. A. Levkovskii V. B. Rozanov V. E. Sherman 《Journal of Experimental and Theoretical Physics》2001,92(1):69-77
The thermonuclear gain G for bulk and spark ignitions are calculated using a mathematical simulation of thermonuclear combustion in a DT plasma of laser targets for various parameters of the target plasma and (isobaric and isochoric) ignitors. The critical parameters of ignitors at which an effective nuclear burst occurs with G ~ 100 are calculated. It is shown that a further increase in the temperature and size of the ignitors virtually does not affect the efficiency of DT fuel burnup. Irrespective of the ignition technique, the value of G can be estimated with the help of a simple asymptotic formula. At the same time, the critical parameters of ignitors are determined to a considerable extent by the mode of ignition and by the target parameters. Spark ignition with an isochoric ignitor corresponding to the fast ignition mode is considered in detail. It is shown that the main critical parameter for optimal isochoric ignitors is their thermal energy liberated upon absorption of an auxiliary ultrashort laser pulse. The critical values of this energy are calculated. 相似文献
12.
G. V. Kuznetsov P. A. Strizhak 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(1):93-100
A theoretical analysis of the ignition of a liquid fuel vapor-air mixture by a moving small source of heating was performed.
A gas-phase model of the ignition with consideration given to heat transfer, liquid fuel evaporation, diffusion and convective
motion of fuel vapor in the oxidizer medium, crystallization of the heating source, kinetics of the vaporization and ignition
processes, temperature dependence of the thermophysical characteristics of the interacting substances, and character of motion
of the heating source in the vapor-gas mixture was developed. The values of the ignition delay time τ
d
, the main characteristic of the process, were determined. It was established how τ
d
depends on the initial temperature, heating source sizes, velocity and trajectory of the heating source, and ambient air
temperature. 相似文献
13.
Austen H. Motily Je Ir Ryu Keunsoo Kim Kenneth Kim Chol-Bum M. Kweon Tonghun Lee 《Proceedings of the Combustion Institute》2021,38(4):5665-5672
Fuel-flexible aircraft propulsion systems using compression ignition engines will require novel strategies for reducing the ignition delay of low-reactivity fuels to feasible timescales. Hot surface ignition of fuel sprays has been implemented in some practical situations, but the complex nature of flame formation within the spray structure poses significant challenges. In order to design next-generation ignition devices, the capacity of hot surface heating elements to promote fuel spray ignition must be investigated. In this study, a rapid compression machine (RCM) was used to examine the ignition process of a single kerosene-based F-24 jet fuel spray with a cylindrical heating element inserted into the spray periphery. The experiments, performed with moderately high injection pressures of 40 MPa, have demonstrated two modes of ignition governed by surface temperature and insertion depth of the heating element. There exists an optimal position where the heating element tip is located in the fuel vapor cone around the liquid spray. For this configuration, a critical surface temperature was identified (~1250 K), above which short ignition delays associated with a “spray ignition” mode are consistently achieved. In this case, a local ignition flame kernel propagates downstream to the flame lift-off length before full ignition of the spray. In comparison, below the critical temperature a slower “volumetric” mode results. The extended ignition delays associated with this mode may be impractical for compression ignition engines operating at high speeds and increased altitude. 相似文献
14.
获得能量增益实现点火是目前激光惯性约束聚变领域研究的主要方向和标志性成果. 在点火靶的设计中有多种可能的候选靶丸,包括碳氢掺杂锗、铍掺杂铜、聚酰亚胺、 碳化硼和金刚石靶丸,其中碳氢和铍靶丸是最主要的候选靶丸.文中主要总结了几种候选靶丸的优缺点及目前研制现状.在国外,碳氢靶丸是目前点火靶的首选靶丸. 与铍靶丸相比,不存在明显的微结构缺陷,制备较容易;靶丸光学透明, 适宜于燃料分层和表征;靶丸在制备上更容易达到点火靶要求. 美国的碳氢点火靶靶丸基本达到了设计要求,这些要求包括几何尺寸、壳层密度、 壳层缺陷、表面光洁度、掺杂水平和杂质含量等.我国的点火靶靶丸研究还处在起步阶段. 相似文献
15.
E. I. Moses R. E. Bonanno C. A. Haynam R. L. Kauffman B. J. MacGowan R. W. Patterson Jr R. H. Sawicki B. M. Van Wonterghem 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):215-218
The National Ignition Facility (NIF) is a 192-beam laser
facility presently under construction at LLNL. When completed, NIF will be a
1.8-MJ, 500-TW ultraviolet laser system. Its missions are to obtain fusion
ignition and to perform high energy density experiments in support of the
US nuclear weapons stockpile. Four of the NIF beams have been commissioned
to demonstrate laser performance and to commission the target area including
target and beam alignment and laser timing. During this time, NIF
demonstrated on a single-beam basis that it will meet its performance goals
and demonstrated its precision and flexibility for pulse shaping, pointing,
timing and beam conditioning. It also performed four important experiments
for Inertial Confinement Fusion and High Energy Density Science. Presently,
the project is installing production hardware to complete the project in
2009 with the goal to begin ignition experiments in 2010. An integrated plan
has been developed including the NIF operations, user equipment such as
diagnostics and cryogenic target capability, and experiments and
calculations to meet this goal. This talk will provide NIF status, the plan
to complete NIF, and the path to ignition. 相似文献
16.
D. O. Glushkov A. V. Zakharevich P. A. Strizhak S. V. Syrodoy 《Thermophysics and Aeromechanics》2016,23(6):887-898
The macroscopic patterns of a temperature change at the center of a droplet of three-component (coal, water, petroleum) composite liquid fuel (CLF) were studied using a low-inertia thermoelectric converter and system of high-speed (up to 105 frames per second) video recording during the induction period at different heating intensity by the air flow with variable parameters: temperature of 670?870 K and motion velocity of 1?4 m/s. The studies were carried out for two groups of CLF compositions: fuel based on brown coal and coal cleaning rejects (filter cake). To assess the effect of liquid combustible component of CLF on characteristics of the ignition process, the corresponding composition of two-component coal-water fuel (CWF) was studied. The stages of inert heating of CLF and CWF droplets with characteristic size corresponding to radius of 0.75?1.5 mm, evaporation of moisture and liquid oil (for CLF), thermal decomposition of the organic part of coal, gas mixture ignition, and carbon burnout were identified. Regularities of changes in the temperature of CLF and CWF droplets at each of identified stages were identified for the cooccurrence of phase transitions and chemical reactions. Comparative analysis of the times of ignition delay and complete combustion of the droplets of examined fuel compositions was performed with varying droplet dimensions, temperatures, and oxidant flow velocity. 相似文献
17.
Simulation results are presented for thermal treatment and ignition of coal-water fuel drops under conditions of radiative-convective heating. The data demonstrate reasonbble compliance between theory and experiment for the integral parameter of ignition process — the delay time of ignition. The radiative component of heat transfer is significant for parameters and conditions of ignition. The increase in the fuel particle size makes this influence bigger. Prognostic potential was evaluated for differnet models of radiative heat tarnsfer. The delay time of ignition obtained from radiative heat transfer model “grey wall” is in good agreement with experimental data. Meanwhile, the method based on radiation diffusion approximation gives the simulation data for delay time much higher than experimental data. It is confirmed that while the process of inflammation of a coal-water particle, the key impotance belongs not to fuel-oxidizer reactions, but rather to a chain of heat treatment events, such as radiative-convective heating, water evaporation, and thermal decomposition of fuel. 相似文献
18.
提出通过离子-电子非平衡物理模型来降低惯性约束聚变中心热斑点火的聚变点火条件。在该物理模型中,强调离子比电子具备更高的温度,从而使得热斑的热核聚变反应增强,轫致辐射和电子热传导造成的能量漏失相对降低。通过对中心热斑的自加热分析和热斑燃烧动力学分析,发现相对于平衡聚变点火模型,非平衡模型可以显著扩大聚变点火区在热斑面密度和热斑温度空间的范围。同时采用LARED-S程序的数值模拟,研究了通过尖峰脉冲波形、二次冲击物理机制强化中心热斑聚变点火的非平衡性。 相似文献
19.
In depth fusion flame spreading with a deuterium-tritium plane fuel density profile for plasma block ignition
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B. Malekynia S. S. Razavipour 《中国物理 B》2012,(12):317-321
<正>Solid-state fuel ignition was given by Chu and Bobin according to the hydrodynamic theory at x = 0 qualitatively. A high threshold energy flux density,i.e.,E* = 4.3×1012 J/m2,has been reached.Recently,fast ignition by employing clean petawatt-picosecond laser pulses was performed.The anomalous phenomena were observed to be based on suppression of prepulses.The accelerated plasma block was used to ignite deuterium-tritium fuel at solid-state density. The detailed analysis of the thermonuclear wave propagation was investigated.Also the fusion conditions at x≠0 layers were clarified by exactly solving hydrodynamic equations for plasma block ignition.In this paper,the applied physical mechanisms are determined for nonlinear force laser driven plasma blocks,thermonuclear reaction,heat transfer, electron-ion equilibration,stopping power of alpha particles,bremsstrahlung,expansion,density dependence,and fluid dynamics.New ignition conditions may be obtained by using temperature equations,including the density profile that is obtained by the continuity equation and expansion velocity.The density is only a function of x and independent of time.The ignition energy flux density,Et*,for the x≠0 layers is 1.95×1012 J/m2.Thus threshold ignition energy in comparison with that at x = 0 layers would be reduced to less than 50 percent. 相似文献
20.
D. Besnard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):207-213
The French Commissariat à l'énergie Atomique (CEA) is
currently building the Laser MegaJoule (LMJ), a 240-beam laser facility, at
the CEA Laboratory CESTA near Bordeaux. LMJ will be a cornerstone of CEA's
“Programme Simulation”, the French Stockpile Stewardship Program. LMJ is
designed to deliver about 2 MJ of 0.35 μm light to targets for high
energy density physics experiments, among which fusion experiments. LMJ
technological choices were validated with the Ligne d'Intégration Laser
(LIL), a scale 1 prototype of one LMJ bundle, built at CEA/CESTA. Plasma
experiments started at the end of 2004 on LIL, which is already open to the
scientific community through the Plasma and Lasers Institute. The
construction of the LMJ building itself started in March of 2003. LMJ will
be gradually commissioned from early 2011, and after an experimental program
to progress toward fusion, the first fusion experiments will begin late
2012. 相似文献