共查询到20条相似文献,搜索用时 31 毫秒
1.
Moo S.P. Chakrabarty C.K. Lee S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(3):515-519
The results of an experimental study of the ion beam properties of a 3.3-kJ, 15-kV plasma focus are reported. The plasma focus is operated at 3 torr deuterium, and neutron yield measurements are made with a copper obstacle or deuterated target placed at various axial positions from the end of the anode. It is found that in the normal operation of the focus without an obstacle or target, less than 15% of the neutrons are produced within the pinch column, and that more than 85% of the neutrons arise from the deuterium-ion-beam bombardment of the deuterium gas in the region 20-60 mm from the end of the anode. The neutron production is highest between 30-40 mm from the anode. The results are valid only for a small focus 相似文献
2.
Coulomb expansion of deuterated methane clusters irradiated by an ultrashort intense laser pulse 下载免费PDF全文
The simulations of three-dimensional particle dynamics show that when irradiated by an ultrashort intense laser pulse, the deuterated methane cluster expands and the majority of deuterons overrun the more slowly expanding carbon ions, resulting in the creation of two separated subelusters. The enhanced deuteron kinetic energy and a narrow peak around the energy maximum in the deuteron energy distribution make a considerable contribution to the efficiency of nuclear fusion compared with the ease of homonuelear deuterium clusters. With the intense laser irradiation, the nuclear fusion yield increases with the increase of the cluster size, so that deuterated heteronuelear clusters with larger sizes are required to achieve a greater neutron yield. 相似文献
3.
The results of experiments on neutron generation caused by nanosecond discharges in a deuterium medium are presented. The experiments are performed using two types of potential electrodes (anodes). One of them is fabricated from steel foil, and the other is composed of tungsten wires with split ends. In both cases, a deuterium-saturated zirconium plate is employed as a flat grounded cathode. With a tungsten anode, deuterium ions generated by field ionization are demonstrated to constitute the determining part of ions involved in the acceleration process and the neutron yield arising from the reaction 2H(d, n)3He is about four times greater than that inherent to the steel-foil anode. In this case, the maximum neutron yield is 1.2 × 104 neutron/ shot, and the duration of neutron emission from the cathode is 1.5 ns. 相似文献
4.
赵磊 徐妙华 张翌航 张喆 朱保君 姜炜曼 张笑鹏 赵旭 仝博伟 贺书凯 卢峰 吴玉迟 周维民 张发强 周凯南 谢娜 黄征 仲佳勇 谷渝秋 李玉同 李英骏 《物理学报》2018,67(22):222101-222101
在利用超强激光驱动中子源的研究和应用研究中,中子源的产额及其角分布至关重要.我们在星光Ⅲ号激光装置上采用气泡探测器对强激光驱动的中子源的产额及其角分布进行了测量.利用超强皮秒激光与碳氘薄膜靶相互作用产生高能氘离子束撞击次级碳氘靶,通过氘-氘核反应产生准单能快中子.实验发现中子束的发射具有一定的方向性,在入射氘离子的传输方向上中子束具有更高的强度,测量得到的中子束最大强度为5.13×107 n/sr.利用实验测量的氘离子能谱和角分布对中子束角分布进行了理论计算,结果与实验测量基本一致. 相似文献
5.
Effects of deuteration on the structure of NH_4H_2PO_4 crystals characterized by neutron diffraction 下载免费PDF全文
《中国物理 B》2019,(1)
A series of deuterated ammonium dihydrogen phosphate(DADP) crystals were grown and their structures were investigated by using powder neutron diffraction method. In the entire composition range, the deuterated level in the crystals is lower compared with the aqueous growth solution. The deuterium segregation coefficient in the crystals decreases with increasing deuterium content of the solution. The deuterium content in the NH_4~+ group is higher than that in H_2PO_4~- group.In addition, the variations of lattice parameters are shown here. 相似文献
6.
O. D. Dalkarov M. A. Negodaev A. S. Rusetskii A. P. Chubenko Yu. L. Pivovarov T. A. Tukhfatullin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2020,14(2):220-225
The interaction between a deuterium ion (D+) beam and deuterium-enriched Pd and Ti targets are studied using the HELIS ion accelerator (Lebedev Physical Institute). The neutron yield is determined from the DD reaction in the deuterated Pd target whose surface is irradiated with a D+-ion beam with an energy of 20 keV. The neutron flux is measured in the D+-ion-beam direction as a function of the angle β of target rotation relative to the beam axis using a multichannel detector based on 3He counters. Significant anisotropy (orientation effect) of the neutron yield is observed; it is two times higher at β = 0° than at β = ±30°. The orientation effect can be associated with channeling and the so-called flux-peaking effect. It is studied by computer simulations using the BCM-2.0 code. The enhanced density of the D+ flux between the (200) planes of a Pd crystal (where implanted D is located) at zero angle of incidence with respect to these planes makes it possible to qualitatively explain the observed orientation effect. No effect is observed in a homogeneous target of deuterated titanium. 相似文献
7.
A SiO2 aerogel with absorbed deuterium is proposed as a target for the fusion reaction d + d → He3 + n induced by a superintense ultrashort laser pulse. The multiple inner ionization of oxygen and silicon atoms in the aerogel skeleton occurs in the superintense laser field. All the formed free electrons are heated and removed from the aerogel skeleton by the laser field at the front edge of the laser pulse. The subsequent Coulomb explosion of the deuterated charged aerogel skeleton propels the deuterium ions up to kinetic energies of ten keV and higher. The neutron yield is estimated at up to 105 neutrons per laser pulse for ~200–500 ps if the peak intensity is 1018 W/cm2 and the pulse duration is 35 fs. 相似文献
8.
采用简化库仑爆炸模型对强激光脉冲照射氘代乙烷团簇发生的库仑爆炸过程进行数值模拟,研究了氘代乙烷团簇爆炸产生的氘核动能、中子产额与团簇尺寸的关系,且与氘代甲烷团簇产生的氘核动能及中子产额进行了比较.研究表明,尺寸为5 nm的氘代乙烷团簇在发生库仑爆炸后氘核的最大动能为20.96 keV,获得的中子产额为6.31×105,比同尺寸氘代甲烷团簇产生的氘核最大动能及中子产额更大.因此相对于氘代甲烷团簇,大尺寸的氘代乙烷团簇更适合作为激光驱动团簇库仑爆炸获得高额中子的靶材,这与报道的实验推论相一致. 相似文献
9.
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
10.
This Letter reports the order of magnitude enhancement in neutron yield from Sahand plasma focus device with krypton seeded deuterium operation. The highest average neutron yield of 2.2×109 neutrons per shot was achieved at 1.00 Torr deuterium with 3% krypton which is higher than the best average neutron yield of 3.18×108 neutrons per shot for pure deuterium operation. Estimation of average neutron energy showed that the maximum and minimum average energies are 2.98±0.6 MeV at 16 kV in 0.25 Torr deuterium with 3% Kr and 2.07±0.2 MeV at 18 kV operation in 0.5 Torr deuterium with 3% Kr, respectively. The anisotropy of neutron emission from Sahand DPF showed that the neutrons are produced mainly by beam-target mechanisms. 相似文献
11.
Results of studying low-energy nuclear reactions at the HELIS facility (LPI) are presented. Investigations of yields from DD reactions in deuterated crystal structures at deuteron energies of 10 to 25 keV show a considerable enhancement effect. It is shown that exposure of the deuterated targets to the Н+ (proton) and Ne+ beams with energies from 10 to 25 keV and an X-ray beam with the energy of 20 to 30 keV stimulates DD reaction yields. For the CVD diamond target, it is shown that its orientation with respect to the deuteron beam affects the neutron yield. The D+ beam is shown to cause much higher heat release in the TiDx target than the Н+ and Ne+ beams, and this heat release depends on the deuterium concentration in the target and the current density of the deuteron beam. 相似文献
12.
超强超短脉冲激光诱发大尺度氘团簇聚变 总被引:3,自引:3,他引:0
利用低温脉冲气阀获得了平均含有3×103氘原子的氘团簇。在飞秒激光装置上实现了氘团簇聚变,每发中子产额为1×103。中子产额对激光功率密度敏感,保持激光能量不变,随着激光焦斑的变大,DD聚变中子产额逐渐增加,最大值出现在激光焦斑为470 mm时;继续增大激光焦斑,没有观察到中子信号。实验结果还表明激光氘团簇聚变发生的区域主要是激光辐照的等离子体热区,此区域内邻近氘团簇库仑爆炸发射的高能氘离子碰撞引发聚变反应。 相似文献
13.
V. M. Milkov Ts. Ts. Panteleev A. Bogdzel V. N. Shvetsov S. Kutuzov S. B. Borzakov P. V. Sedyshev 《Physics of Particles and Nuclei Letters》2012,9(6-7):508-516
A prototype of a neutron spectrometer based on a gas proportional counter with recoil-proton registration is created at the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (FLNP JINR) in Dubna. The spectrometer is developed to measure the kinetic energy of protons scattered elastically at small angles that are produced by (n, p) reaction in an environment containing hydrogen. The elaborated prototype consists of two cylindrical proportional counters used as cathodes. They are placed in a gas environment with a common centrally situated anode wire. Studies on the characteristics of the neutron spectrometer were conducted using 252Cf and 239Pu-Be radioisotope neutron sources. Measurements were made with monoenergetic neutrons produced by the 7Li(p, n)7Be reaction when a thin lithium target was bombarded with a proton beam from an EG-5 electrostatic accelerator, as well as with neutrons from the reaction D(d, n) 3He with a gas deuterium target. 相似文献
14.
Results of neutron counting experiments during deuterium implantation into titanium and copper are reported. Models for neutron
yield have been developed by taking into account different solid state effects like energy degradation of incident ions, energy
dependent d-d fusion cross section and diffusion of implanted deuterium possibly influenced by surface desorption and formation
of metal deuterides. The asymptotic time dependence of the neutron yield during implantation has been compared with the experimental
results. Using these results, solid state processes that might occur during deuterium implantation into these metals are inferred. 相似文献
15.
A. Yu. Didyk E. Haewska A. Hofman V. S. Kulikauskas S. V. Serushkin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(4):814-820
Using the method of the elastic recoil detection (ERD) of hydrogen nuclei and a Plasma Focus setup (PF-4), we study the processes of the storage and redistribution of hydrogen and deuterium atoms in a stack of two tantalum foils and a deuterated polyethylene film sandwiched between them under pulsed irradiation with hot nitrogen plasma. It is established that the redistribution of implanted deuterium and hydrogen occurs at greater depths in both tantalum foils after 30 pulses of nitrogen plasma. The maximum concentrations of hydrogen and deuterium, namely 7 and 45 at % are observed on the surface of the second tantalum foil which is more distant from the PF-4 setup. The redistribution of deuterium from deuterated polyethylene onto the surface and volume of both Ta foils is observed. The observed phenomenon can be explained by the breaking of chemical bonds in the deuterated polyethylene and the transfer of freed deuterium into the Ta foils under the action of strong shock waves formed in the structure, as well as the accelerated diffusion of hydrogen and deuterium in the stress field caused by the shock wave. 相似文献
16.
Pencer J Mills T Anghel V Krueger S Epand RM Katsaras J 《The European physical journal. E, Soft matter》2005,18(4):447-458
Using coarse grained models of heterogeneous vesicles we
demonstrate the potential for small-angle neutron scattering
(SANS) to detect and distinguish between two different categories
of lateral segregation: 1) unilamellar vesicles (ULV) containing a
single domain and 2) the formation of several small domains or
“clusters” (~10 nm in radius) on a ULV. Exploiting the
unique sensitivity of neutron scattering to differences between
hydrogen and deuterium, we show that the liquid ordered (lo)
DPPC-rich phase can be selectively labeled using chain deuterated
dipalymitoyl phosphatidylcholine (dDPPC), which greatly
facilitates the use of SANS to detect membrane domains. SANS
experiments are then performed in order to detect and
characterize, on nanometer length scales, lateral heterogeneities,
or so-called “rafts”, in ~30 nm radius low polydispersity
ULV made up of ternary mixtures of phospholipids and cholesterol.
For 1:1:1 DOPC:DPPC:cholesterol (DDC) ULV we find evidence for the
formation of lateral heterogeneities on cooling below 30 °C. These heterogeneities do not appear when DOPC is
replaced by SOPC. Fits to the experimental data using coarse
grained models show that, at room temperature, DDC ULV each
exhibit approximately 30 domains with average radii of ~10 nm. 相似文献
17.
18.
Effect of laser spot size on fusion neutron yield in laser--deuterium cluster interactions 下载免费PDF全文
The effect of the laser spot size on the neutron yield of table-top nuclear fusion from explosions of a femtosecond intense laser pulse heated deuterium clusters is investigated by using a simplified model, in which the cluster size distribution and the energy attenuation of the laser as it propagates through the cluster jet are taken into account. It has been found that there exists a proper laser spot size for the maximum fusion neutron yield for a given laser pulse and a specific deuterium gas cluster jet. The proper spot size, which is dependent on the laser parameters and the cluster jet parameters, has been calculated and compared with the available experimental data. A reasonable agreement between the calculated results and the published experimental results is found. 相似文献
19.
Neutrons (2.45MeV) from deuterium cluster fusion induced by the intense femtosecond (3Ors) laser pulse are experimentally demonstrated. The average neutron yield 103 per shot is obtained. It is found that the yield slightly increases with the increasing laser spot size. No neutron can be observed when the laser intensity I 〈 4.3 × 10^15 W/cm^2. 相似文献
20.
Milanese M.M. Moroso R.L. Pouzo J.O. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(4):373-377
Further results regarding the sudden drop of dense plasma focus (DPF) neutron yield at low pressure are presented. Experimental measurements of temporal evolution of magnetic piston MP (interface plasma-magnetic field) and current sheath ionizing front IF (interface plasma-neutral gas) are performed in the radial compression stage of DPF discharges. At the optimum deuterium pressure for neutron yield (1.5 mb), MP and IF have similar r(t) functions, so that the thickness of the sheath remains practically constant (~0.2 cm) in the whole stage. At the lower pressure limit for neutron yield (1 mb) the sheath begins the radial compression stage with a smaller thickness (~0.1 cm) and in the last 35 ns the IF moves forward (relatively to the MP) with a velocity of 7.5E+7 cm/s and the thickness in the layer reaches a value of ~0.5 cm. This sudden acceleration of the IF is interpreted as the main cause of the lower pressure limit in the neutron yield 相似文献