Effect of Internal Breeding of Tritium and Helium-3 on the Ignition of an ICF Fuel Pellet

Self-heating condition and following ignition in an Inertial Confinement Fusion (ICF) fuel pellet is evaluated by calculating the power equations, dynamically. In fact, the self-heating condition is a criterion that determines the minimum parameters of a fuel (such as temperature, density and areal density) that can be ignited. Deuterium is the main component of ICF fuels as large amounts of it are naturally available. In addition, the use of deuterium as a fuel in ICF causes the production of tritium and helium-3. However, pure deuterium has a high ignition temperature (\(\hbox {T}\ge 40\,\hbox {keV}\)) which makes it inefficient. In this paper, the power equations are solved, dynamically, and it has been indicated that internal tritium and helium-3 production at early evolution of compressed deuterium fuel causes ignition at lower predicted temperatures.     

Ignition of a Deuterium Micro-Detonation with a Gigavolt Super Marx Generator

The Centurion–Halite experiment demonstrated the feasibility of igniting a deuterium–tritium micro-explosion with an energy of not more than a few megajoule, and the Mike test, the feasibility of a pure deuterium explosion with an energy of more than 10⁶ MJ. In both cases the ignition energy was supplied by a fission bomb explosive. While an energy of a few megajoule, to be released in the time required of less than 10⁻⁹ s, can be supplied by lasers and intense particle beams, this is not enough to ignite a pure deuterium explosion. Because the deuterium–tritium reaction depends on the availability of lithium, the non-fission ignition of a pure deuterium fusion reaction would be highly desirable. It is shown that this goal can conceivably be reached with a “Super Marx Generator”, where a large number of “ordinary” Marx generators charge (magnetically insulated) fast high voltage capacitors of a second stage Marx generator, called a “Super Marx Generator”, ultimately reaching gigavolt potentials with an energy output in excess of 100 MJ. An intense 10⁷ Ampere-GeV proton beam drawn from a “Super Marx Generator” can ignite a deuterium thermonuclear detonation wave in a compressed deuterium cylinder, where the strong magnetic field of the proton beam entraps the charged fusion reaction products inside the cylinder. In solving the stand-off problem, the stiffness of a GeV proton beam permits to place the deuterium target at a comparatively large distance from the wall of a cavity confining the deuterium micro-explosion.

Measurement of Neutron Flux Distribution in Critical Assembly with Position-Sensitive Helium-3 Proportional Counter

Neutron flux distributions in the Kyoto University Critical Assembly were measured with a position-sensitive ³He proportional counter. The authors examined the results of the first attempt to apply the position-sensitive counter for such measurement in the critical assembly. Some problems to be solved were drawn from the present examination for the further development of this type of counters. The counter had a sensitive length of 118 cm and an outer diameter of 2.5 cm. The counting gas was a mixture of ³He (270 Pa) and CF₄ (3×10⁴Pa). The observed distribution was very similar to that measured with the conventional gold wire activation method. The position resolution was 2.7 cm in the experimental condition. The measurable neutron flux (at peak position) was limited to the order of 10⁴ n-cm^?2-s^?1 due to the pileup of signal pulses. The counter was a useful tool to quickly measure the flux distribution in the assembly.     

Study of the Ignition Requirements and Burn Characteristics of Aneutronic Fusion in Degenerate Plasma

The reactions such as; D?+?³ He and p?+?¹¹B are aneutronic fusion reactions that, in characteristic conditions create degenerate plasma. The electronic stopping power of degenerate plasma is smaller than the classical plasma, because some transitions between the electron states are forbidden. The equations that predict the behavior of these plasmas are different from the classical ones, and this is the main factor in decreasing the ignition temperature of the plasma. In this research, the nuclear fusion in deuterium–helium with a small seeding born, D/³ He/¹¹B, is considered using a time dependent model based on nuclear reactions, including ion-electron collisions, Bremsstrahlung losses and mechanical expansion. The effect of the initial born concentration on ignition temperature and energy gain is analyzed with calculating the effect of radiation loss in ignition temperature.     

Development of Position Sensitive Helium-3 Proportional Counter for Thermal Neutrons with Novel Signal Readout

A position sensitive ³He proportional counter for thermal neutrons with a novel signal read- out method which has two pre-amplifiers at only one end of the counter body has been developed. It has an advantage for usage in a special environment, such as in a subcritical facility or in water, or for insertion into a narrow space. The characteristics of the counter were evaluated with thermal neutrons. The position resolution was 7 mm with an effective length of 1,200 mm. The integral non-linearity of position signal was less than 0.5%.     

Fusion-neutron production in the TFTR with Deuterium neutral-beam injection

We report measurements of the fusion reaction rate in the Tokamak Fusion Test Reactor (TFTR) covering a wide range of plasma conditions and injected neutral-beam powers up to 6.3 MW. The fusion neutron production rate in beam-injected plasmas decreases slightly with increasing plasma density n_e, even though the energy confinement parameter n_eE generally increases with density. The measurements indicate and Fokker-Planck simulations show that with increasing density the source of fusion neutrons evolves from mainly beam-beam and beam-target reactions at very low n_e to a combination of beam-target and thermonuclear reactions at high n_e. At a given plasma current, the reduction in neutron source strength at higher n_e is due to both a decrease in electron temperature and in beam-beam reaction rate. The Fokker-Planck simulations also show that at low n_e, plasma rotation can appreciably reduce the beam-target reaction rate for experiments with coinjection only. The variation of neutron source strength with plasma and beam parameters is as expected for beam-dominated regimes. However, the Fokker-Planck simulations systematically overestimate the measured source strength by a factor of 2–3; the source of this discrepancy has not yet been identified.On leave from RCA David Sarnoff Research Center, Princeton, New Jersey 08540.On assignment from Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831.On leave from Idaho National Engineering Laboratory, EG&G Idaho, Inc., Idaho Falls, Idaho 83415.     

A Long and Slender Position-Sensitive Helium-3 Proportional Counter with an Anode Wire Supported by a Ladder-Shaped Solid Insulator

A long and slender position-sensitive ³He proportional counter with an outer diameter of 8 mm and an effective length of 1.2 m has been developed to measure neutron flux distributions in a critical assembly. Because it is difficult to make such a long and slender counter of conventional structure where an anode wire is stretched at the center of a cylindrical cathode tube, three prototype electrode systems of which anode wires are supported by insulator plates have been proposed. Among these three electrode systems, the electrode system of which anode wire is stuck on a ladder-shaped insulator has been adopted. The neutron flux distributions in the core of the Kyoto University Critical Assembly (KUCA) have been measured with the counter. Some non-uniformity of the detection efficiency has been observed throughout the counter. This non-uniformity has been corrected by calibrating the position-dependent detection efficiency with a gold wire activation method. A fairly satisfactory distribution, where the relative deviation from the gold wire activation method is 5.0%, has been obtained. Though the non-uniformity of the detection efficiency should be solved for precise measurements, the counter can be used for quick and rough measurements of neutron flux distributions.     

氕氘在锆膜中的分布

电阻蒸发制备的锆膜氢化后，利用二次离子质谱(SIMS)对其进行了深度剖析与成像分析，结果表明氕与氘在锆膜深度分布均匀，在过渡层中呈递减分布，并消失于过渡层与衬底的交界处。锆膜在n(H)：n(D)=0.82的气氛中氢化时，会因同位素效应而使氕氘化锆膜中氕的含量高于氘的含量。锆膜表面若有铝、铁、钾以及钠等元素的污染时，会造成表面氕与氘分布不均匀，氕与氘的不均匀分布分别与铝及锆的不均匀分布有关。     

The Potential of Fast Ignition and Related Experiments with a Petawatt Laser Facility

A model of energy gain induced by fast ignition of thermonuclear burn in compressed deuterium-tritium fuel, is used to show the potential for 300× gain with a driver energy of 1 MJ, if the National Ignition Facility (NIF) were to be adapted for fast ignition. The physics of fast ignition has been studied using a petawatt laser facility at the Lawrence Livermore National Laboratory. Laser plasma interaction in a preformed plasma on a solid target leads to relativistic self-focusing evidenced by x-ray images. Absorption of the laser radiation transfers energy to an intense source of relativistic electrons. Good conversion efficiency into a wide angular distribution is reported. Heating by the electrons in solid density CD₂ produces 0.5 to 1 keV temperature, inferred from the D-D thermo-nuclear neutron yield.     

氘在Ti-32Mo-5Nb合金中的行为

利用质子增强背散射和Ｘ射线衍射等方法,对氘在β相相的Ｔｉ－３２Ｍｏ－５Ｎｂ合金中的深度分布及Ｔｉ３２－Ｍｏ－５Ｎｂ合金吸氘前后的相结构等进行了分析研究。结果表明：该合金在低温阶段的吸氘速率明显现于纯钛,平均氘钛原子 ２．５,其中一部分氘与合金中的钛生成ＴｉＤ１．９７１,另一部分氘则固溶在Ｔｉ－３２Ｍｏ－５Ｎｂ合金中。     

Radiation Emission Correlated with the Evolution of Current Sheath from a Deuterium Plasma Focus

The time resolved emission of neutrons and X-rays (both soft and hard) is correlated with the current sheath evolution during the radial phase of a 3.2 kJ Mather-type plasma focus device operated in deuterium at an optimised pressure of 4 mbar. A three-frame computer-controlled laser shadowgraphy system was incorporated in the experiment to investigate the time evolution of the radial phase of the plasma focus. The dynamics of the sheath was then correlated with the time resolved X-rays and neutron emission. The time-resolved neuron and hard X-ray emission was detected by a Scintillator-photomultiplier system while the time resolved soft X-rays were detected employing filtered PIN photo diodes. The observations were recorded with a temporal accuracy of a few ns. For the reference, the total neutron yield was also monitored by an Indium Foil activation detector. The correlation with the High Voltage Probe signal of the discharge, together with the X-ray and neutron emission regimes enabled to identify the important periods of the sheath evolution i.e. the radial compression (pre focus), minimum pinch radius (focus) and the post focus phenomena. During the initial stage of the radial phase, velocities of 10–23 cm/μs, while at the later stage of the radial phase (up till the compression), velocities up to 32–42 cm/μs were measured in our experiment. For the discharges with the lower neutron yield (lower than the average value ~1 × 10⁸ n/discharge), the current sheath appears to be disturbed and neutron and hard X-ray signal profiles do not carry much information whereas the soft X-ray emission is significant. For the discharges with high neutron yield (higher than the average value), the current sheath has a smooth structure until the maximum compression occurs. Hard X-ray emission is maximum for the discharges with high neutron yield, especially whenever there is development of m = 0 instability compressing the column to very high densities. The neutron are emitted long after the maximum compression supporting the beam target fusion. For the discharges with High neutron yield, the soft X-ray production is less as compared to the discharges with low neutron yield.     

钛膜表面氧化层对吸氘性能的影响

利用金属氢化物热力学和动力学参数测试系统对表面具有氧化层的钛膜进行了恒温吸氘和变温吸氘实验。结果表明：试样恒温吸氘时。吸氘速率随氧化层厚度的增加而变慢，达到吸氘平衡的时间也变长；试样变温吸氘时，在相同的升温速率和相同的初始氘气压力下，吸氘温度随氧化层厚度的增加而升高，表明钛膜表面氧化层具有一定的阻氘性能。     

Plasma Deposition of Fluorinated Amorphous Carbon with CHF_3 and C_6H_6 Mixture

1. IntroductionTO improve device speed, device packing densityand the number of functions that can be residedon a single chip, new materials with low dielectricconstant (k) in use for interlayer dielectric (ILD)as well as alternative architectures have been proposed to replace the current SiOZ interconnectingtechnology [l]. As organic polymers such as polytetra fluoroethylene (PTFE) have a low k, they arepromising materials in use for ILD. However, theirpoor adhesion with St substrate an…     

Comprehensive Commissioning Test of Cold Neutron Source with Deuterium with Reactor Power Operation in CARR

<正>The single-phase liquid deuterium was adopted and used as the moderator of cold neutron in China Advanced Research Reactor(CARR).Liquid deuterium moderator go through in-pile device where heat exchanger and thermosiphon loop located and was cooled by the closed naturally cycling and helium interlining in     

3D Simulation of Solid-Melt Mixture Flow with Melt Solidification Using a Finite Volume Particle Method

Relocation and freezing of molten core materials mixed with solid phases are among the important thermal-hydraulic phenomena in core disruptive accidents of a liquid-metal-cooled reactor (LMR). To simulate such behavior of molten metal mixed with solid particles flowing onto cold structures, a computational framework was investigated using two moving particle methods, namely, the finite volume particle (FVP) method and the distinct element method (DEM). In FVP, the fluid movement and phase changes are modeled through neighboring fluid particle interactions. For mixed-flow calculations, FVP was coupled with DEM to represent interactions between solid particles and between solid particles and the wall. A 3D computer code developed for solid-liquid mixture flows was validated by a series of pure-and mixed-melt freezing experiments using a low-melting-point alloy. A comparison between the results of experiments and simulations demonstrates that the present computational framework based on FVP and DEM is applicable to numerical simulations of solid-liquid mixture flows with freezing process under solid particle influences.     

真空弧氘离子源中杂质氕对束流品质的影响

分析了真空弧氘离子源中杂质的主要构成,并着重分析了杂质氕的成因及其对氘离子源性能的影响.对单次脉冲和低重复频率脉冲工作状态下的真空弧氘离子源进行了光谱诊断实验和核反应分析实验,结果表明,氘离子源等离子体中的确含有较多的杂质氕,可对氘离子源的引出束流品质产生较大的危害.并对如何减小杂质氕的影响提出了建议.     

The Role of the Collisions on the Weibel Instability Growth Rate in the Fast Ignition Scenario

In this paper, the effects of Coulomb elctron-ion collisions and plasma density gradient, \(\eta\), on the Weibel instability in inertial confinement fusion are investigated. The results are indicative that the corrected collision of Weibel instability growth rate of the relativistic region near the corona, \(\eta >0.3\), increases with increasing relativistic parameter, \(\upgamma\). Also, near the fuel core as \(\eta\) goes down, the corrected collisional growth rate decreases with increasing \(\upgamma\) for \(\mathrm{{\upgamma }}<6\) and and increases with increasing \(\upgamma\) for \(\upgamma >6\). Therefore, for \(\upgamma <6\), the effect of collision and fuel density gradient tend to stabilize the Weibel instability in fuel core, with the Weibel growth rate below the collisionless value. Also deposition condition of relativistic electron beam energy can be shifted to the fuel core for the suitable ignition.     

Interaction of hydrogen isotopes with metals: Deuterium trapped at lattice defects in palladium

From an interplay between theory based on the effective-medium scheme and experiments, an extremely simple picture has evolved which is capable of describing a vast number of experimental quantities related to interaction of hydrogen with metals, especially the trapping of hydrogen at defects. It is shown that the trap strengths are determined mainly by the interstitial electron density, and any open structures in the lattice leads to a trap, with the vacancies and voids being the strongest traps. It is also found theoretically and experimentally that up to six hydrogen atoms can be accomodated in a vacancy, and the change in trap strengths with occupancy has been determined. Recent results for the trapping of deuterium to defects in Pd are discussed.     

关于增加核电厂场外应急撤离时间管理要求的建议

在制定核电厂应急撤离计划和应急决策时,撤离时间估算是一项重要的技术支持手段。本文根据我国场外应急撤离的管理要求现状,借鉴美国撤离时间估算的相关经验,对核电厂场外应急撤离时间问题进行了分析,同时建议我国相关核安全管理规定中增加场外应急撤离时间的要求。