Pressure ionization in laser-fusion target simulation

Accurate simulation of high density target implosion requires material properties (ionization, pressure, energy, opacity and transport coefficients) at densities where bound electrons are significantly perturbed by neighboring atoms. In modern laser-fusion simulation codes, this data is supplied by tables and/or calculated from a Stromgren model for ionization equilibrium. Improvements have been made in the Stromgren average-atom model which aim at assuring thermodynamic consistency and obtaining better agreement with more elaborate calculations. Arbitrary degeneracy is allowed for the free electrons. Consistent Coulomb contributions to pressure and continuum lowering are obtained. A new pressure ionization scheme merges bound electrons into the continuum as a smooth function of density and the corresponding contribution to pressure is calculated. Results are shown for aluminum.     

Thermonuclear gain of ICF targets with direct heating of ignitor

As the way of decreasing of the driver energy which is needed for ignition of the LCF targets, the conception of separation of the process of compression of the main mass of the fuel and the process of heating of the ignitor is suggested. Thermonuclear gain of the target with direct heating of the ignitor is calculated. It's shown that using the target with direct heating of the ignitor may lead to considerable decreasing of the driver energy: in (10–20) times for breakeven, and in (5–10) times for thermonuclear gain of 100–300 in comparison with the traditional conception of simultaneous compression and heating of the ICF target.     

Numerical design of a two-cascade cylindrical microtarget for shock-free compression

We present the numerical design of a two-cascade target. The desired target design is intended to provide a shock-free compression of the central DT core, where the fusion reactions take place. We obtain the formula for the energy deposition into each cascade internal layer for both known and unknown energy depositions into the external target layer. The two-cascade target design helps to increase the energy deposition into the DT layer and therefore decrease the energy required for the target ignition.     

Thermonuclear fusion in a strong laser field

Thermonuclear fusion induced by the irradiation of solid deuterated cluster targets and foils with fields of strong femtosecond and picosecond laser pulses is discussed. The thermonuclear-fusion process D(d, n)³He in a collision of two deuterons at an energy of 50 to 100 keV in a deuterium cluster target irradiated with a strong laser pulse is discussed. A theory of thermonuclear fusion proceeding upon the irradiation of clusters formed by deuterium iodide (DI) molecules with the field of a superintense femtosecond laser pulse is developed. This theory is based on an above-barrier process in which the sequential multiple inner ionization of atomic ions within a cluster is accompanied by field-induced outer ionization. The yield of neutrons from thermonuclear fusion in a deuteron-deuteron collision after the completion of a laser pulse is calculated. The yield of neutrons is determined for the thermonuclear-fusion reaction proceeding in the interaction of an intense picosecond laser pulse with thin TiD₂ foils. A multiple ionization of titanium atoms at the front edge of the laser pulse is considered. The heating of free electron occurs in induced inverse bremsstrahlung in the process of electron scattering on multiply charged titanium ions. The yield of alpha particles in the thermonuclear-fusion reaction involving protons and ¹¹B nuclei that is induced in microdrops by a strong laser field is determined. Experimental data on laser-induced thermonuclear fusion are discussed.     

Thermonuclear Instabilities and Fueling in a Tokamak Reactor

The problem of fueling is of primary importance in the conceptual design of a fusion reactor. We consider a possible mechanism of supplying fresh fuel from a cold-plasma layer at the surface of the plasma. The existence of an energetic component of ions, viz, the alpha particles, may excite unstable collective oscillations of the plasma (called the thermonuclear instabilities). Such instabilities could give rise to microscopic processes which, in principle, would allow influx of fresh fuel while helping efflux of reaction products. A three-regime model is used to understand the nature of such fueling mechanisms and the possibility of using a cold-plasma layer as a surface fueling source.     

Compression of two-cascade liners with an internal capillary discharge stage

It is demonstrated that columns of dense high-temperature plasma with various elemental compositions can be obtained when two-stage liners with an internal capillary discharge stage are compressed by current pulses from high-current generators. We also show that high-power pulses of K-line x-rays can be obtained and a homogeneous column of iron-containing plasma can be produced with near-optimal parameters in regard to creating a collisionally pumped 3p–3s x-ray laser based on neonlike iron. Institute of Strong-Current Electronics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 33–39, December, 1995.     

Heavy ion inertial fusion: Initial survey of target gain versus ion-beam parameters

Inertial-fusion targets have been designed for use with heavy-ion accelerators as drivers in fusion energy power plants. We have made an initial survey of target gain versus beam energy, power, focal radius, and ion range. This provides input for understanding the trade-offs among accelerator designs.     

人造小太阳——受控核聚变

希腊神话中普罗米修斯为了使人类从藏身的洞穴中走出来过上光明的日子,他用茴香管盗来了太阳上的火种,因而被天神绑在高加索山崖上受了3万年的煎熬.在希腊的文学作品中,他便成了一个为人类文明而不避艰险的英雄.马克思也称他为"哲学史上最高尚的圣者和殉道者".     

Helium-3 as a Perspective Fuel for Power Generation through Aneutronic Thermonuclear Fusion

Physics of Atomic Nuclei - The aneutronic D3–He (deuterium–helium-3) fuel cycle is considered as a viable alternative to D–T (deuterium–tritium) fusion since it is...     

Production of Transuranium Nuclides in Pulsed Neutron Fluxes from Thermonuclear Explosions

The production of transuranium nuclides in pulsed neutron fluxes from thermonuclear explosions has been studied within the kinetic model of the astrophysical r-process taking into account the time dependence of external parameters and processes accompanying the beta decay of neutron-rich nuclei. Neutron fluxes depending on the time in the range of ~10^–6 s have been simulated within the developed adiabatic binary model. The probabilities of beta-delayed processes have been calculated within the microscopic theory of finite Fermi systems. The yields of transuranium nuclides Y(A) have been calculated for three experimental thermonuclear explosions Mike (Y_M), Par (Y_P), and Barbel (Y_B) (United States). The rms deviations of the calculations from experimental data are 91, 33, and 29% for Y_M, Y_P, and Y_B, respectively. These deviations are much smaller than those for other known calculations and are comparable with the proposed exponential approximation ensuring rms deviations of 56, 86.8, and 60.2% for Y_M, Y_P, and Y_B, respectively. The even–odd anomaly in the observed yields of heavy nuclei is explained by the dominant effect of processes accompanying the beta decay of heavy neutron-rich isotopes.     

Creation of a diagnostic complex for the characterization of cryogenic laser-fusion targets using the tomography method with probing irradiation in the visible spectrum

We present our results on developing a diagnostic complex for high-precision characterization of the parameters of laser-fusion microobjects, such as microspheres and cryogenic targets (the microobject size is 1–2 mm). The complex operates based on the principle of tomography. The complex consists of (a) the scanning system providing a set of shadow projections of a microobject in the visible range of radiation and (b) specially developed software for 3D reconstruction of the microobject from the set of projections. The spatial resolution of the optical system is 1 μm for a probing-radiation wavelength of 490 nm. The distinctive features of the diagnostic complex are (1) operation with both free-standing and mounted targets and (2) the possibility of scanning the targets from room to cryogenic temperatures. The operation of the complex was demonstrated in the reconstruction of polystyrene microspheres by a large set (80–90) of shadow projections at room and cryogenic temperatures.     

Thermonuclear fusion in the irradiation of large clusters of deuterium iodide with a field of a superatomic femtosecond laser pulse

A theory of thermonuclear fusion caused by the irradiation of deuterium-iodide clusters with the field of a superatomic femtosecond laser pulse is developed. It is based on considering the process in which the sequential above-barrier multiple internal ionization of atomic ions within a cluster is accompanied by external field ionization. The theory is illustrated by taking the example of a cluster that is formed by 10⁶ molecules of deuterium iodide and which is irradiated with a laser pulse of duration 50 fs and intensity 2×10¹⁸ W/cm² at the peak. This case is dominated by I²⁶⁺ atomic ions. The yield of neutrons from thermonuclear fusion in a deuteron-deuteron collision upon the passage of a laser pulse is calculated. The result is 10⁵ neutrons per laser pulse. The mean kinetic energy of deuterons is estimated at 50 keV. Owing to induced inverse bremsstrahlung in scattering on multiply charged atomic ions, the electron temperature increases up to 28 keV. The role of the Mie resonance in the heating of the electron component is discussed.     

国际热核实验反应堆(ITER)计划与未来核聚变能源

能源短缺和环境恶化是人类社会面临的共同挑战.由于资源丰富、环境友好和零碳排放,核聚变能源是未来的理想能源.上世纪90年代以来,磁约束核聚变研究取得重大进展,以建造国际热核实验反应堆(ITER)为标志,聚变能源开发进入工程实施阶段,如果ITER计划取得预期成果,有望在本世纪中叶实现核聚变能源商用化.     

Multi-GeV energy gain in a plasma-wakefield accelerator

A plasma-wakefield accelerator has accelerated particles by over 2.7 GeV in a 10 cm long plasma module. A 28.5 GeV electron beam with 1.8 x 10(10) electrons is compressed to 20 microm longitudinally and focused to a transverse spot size of 10 microm at the entrance of a 10 cm long column of lithium vapor with density 2.8 x 10(17) atoms/cm3. The electron bunch fully ionizes the lithium vapor to create a plasma and then expels the plasma electrons. These electrons return one-half plasma period later driving a large amplitude plasma wake that in turn accelerates particles in the back of the bunch by more than 2.7 GeV.     

关于量子场论、聚变能源、理论生物物理的一些想法

在这么多具有创造性的与会者面前,我讲三点各不相干的粗糙想法,希望大家批评指正.1　量子场论用经典的微扰法作级数展开遇到发散困难,而量子电动力学用费曼图计算则可得精确到好几位与实验符合的结果.有一年,Ａｔｉｙａｈ数学家来京我与他讨论,他表示物理学家搞对了的需要数学家去更好地理解.我体会有如δ函数的故事.几年前,我做多体的超越ＨａｒｔｒｅｅＦｏｃｋ近似时,曾提出一个新方法,框架我已写入理论物理基础这本书中.多体问题的哈氏量在二次量子化形式下与场论的哈氏量可比,而新方法的特点在于用幺正变换逐渐把自共轭的哈氏量对角化.…     

Scalable spin amplification with a gain over a hundred

We propose a scalable and practical implementation of spin amplification which does not require individual addressing nor a specially tailored spin network. We have demonstrated a gain of 140 in a solid-state nuclear spin system of which the spin polarization has been increased to 0.12 using dynamic nuclear polarization with photoexcited triplet electron spins. Spin amplification scalable to a higher gain opens the door to the single spin measurement for a readout of quantum computers as well as practical applications of nuclear magnetic resonance spectroscopy to infinitesimal samples which have been concealed by thermal noise.