Modified Woods-Saxon Potential for Heavy-Ion Fusion Reaction

A modified Woods-Saxon potential （MWS） is proposed for describing nucleus-nucleus interaction based on the Skyrme energy-density functional （SEDF） approach. Fusion barriers for a large number of fusion reactions from light to heavy systems can be described well with this potential （Fig.l）. The calculated fusion excitation functions of reactions ^16O＋^92Zr, ^28Si＋^92Zr, ^16O＋^208pb and ^48Ca＋^208pb are in good agreement with experimental data （Fig.2）.     

Dynamic Study on Entrance-Channel Effects of Symmetry and Asymmetry Reaction System in Heavy-Ion Fusion Reactions

The entrance-channel effects and dynamical mechanisms on the fusion reaction of the symmetry and asymmetry reaction system are studied with the microscopic transport model, i.e. Improved Quantum Molecular Dynamic Model （ImQMD）. From the microscopic dynamical point of view, the relation of the intensity in the population of the superdeformed bands of high-spin states and the entrance-channel effects is explored in the heavy-ion fusion reactions. Two different fusion-evaporation reactions are selected：     

Power Plant for Heavy-Ion DT Fusion with Targets Containing Fissioning Materials

The special features of the concept of a hybrid power-generating plant, which combines the fusion and fission processes in a cylindrical target initiated by a high-power heavy-ion accelerator, are analyzed. The main advantages of the proposed setup are: burning of unenriched ²³⁸U in the reactor cavity, continuous removal of fission products from the core, and impossibility of an uncontrollable nuclear reaction. The characteristics of matched heavy ion accelerator, target, reactor chamber, and blanket with circulating coolant in the blanket are presented, and the power parameters of the electric power plant are estimated. __________ Translated from Atomnaya Energiya,Vol. 99, No. 3, pp. 190–198, September, 2005.     

Minor Actinide Transmutation Potential of Modified PROMETHEUS Fusion Reactor

This study presents the investigation of the burning and/or transmutation (B/T) of minor actinides (MAs) in the modified PROMETHEUS-H fusion reactor. The calculations were performed for an operation period (OP) of up to 10 years by 75% plant factor () under a neutron wall load (P) of 4.7 MW/m². In order to incinerate and transmute the MAs effectively, the transmutation zone (TZ) containing the mixture of MA nuclides, discharged from the pressured water reactor (PWR)-MOX spent fuel, was located in the modified blanket of the PROMETHEUS-H fusion reactor. Two different blanket modifications were considered, (the Models A and B). The MA mixture was spherically prepared and cladded with SiC to prevent fission products from contaminating coolant and the MAs from contacting coolant. Helium was selected for the nuclear heat transfer in the TZ. The effect of the MA volume fraction in the TZ on the B/T was also investigated. The results bring out that the MAs are converted by the transmutation rather than the incineration. Bothmodels can reduce significantly the effective half-lives of the MA nuclides by burning and/or transmuting these nuclides, and at the same time produce substantial electricity insitu.     

Energy Dependence of Dynamic Barrier in Heavy-Ion Fusion Reactions

投影壳模型（PSM）给出的波函数具有好的角动量和宇称，并且不断证实它可以很好地描述原子核的多方面性质。本工作期望采用PSM波函数计算Beta衰变矩阵元能够给出较好的结果。最近，应用投影壳模型初步建立了Gamov—Teller（GT）跃迁的计算程序。     

Inertial Confinement Fusion with a Heavy-Ion Driver-Accelerator and a Cylindrical Target

An economically efficient power plant burning deuterium-tritium fuel can be built using a powerful heavy-ion accelerator of a new type. A multilinear cryogenic cylindrical target, 1 cm long, 0.44 cm in radius, and containing 7.8 mg equimolar DT fuel, is studied as an example. The driver-accelerator gives two different target irradiation regimes. In both regimes, the beams consist of platinum ions, accelerated up to 100 GeV, with different isotopic composition, charged in the first regime only positively and in the second regime positively and negatively. In the first regime, the beam energy is 4.8 MJ and the beam heats in 60 nsec only the target shell. High heating symmetry is achieved by rapidly rotating the beam around the target axis with frequency 1 GHz. The fuel is compressed into a dense filament, where the condition for propagation of a fusion burn wave is satisfied – R 0.4 g/cm². In the second regime, a beam with 0.4 MJ ions heats in 0.2 nsec compressed fuel with power density 2.5·10⁷ TW/cm² up to ignition temperature. The computed energy amplification factor in the target is 200.     

Non-Uniformity of Heavy-Ion Beam Irradiation on a Direct-Driven Pellet in Inertial Confinement Fusion

Heavy-ion-driven fusion (HIF) is a scheme to achieve inertial confinement fusion (ICF). Investigation of the non-uniformity of heavy-ion beam (HIB) irradiation is one of the key issues for ICF driven by powerful heavy-ion beams. Ions in HIB impinge on the pellet surface and deposit their energy in a relatively deep and wide area. Therefore, the non-uniformity of HIB irradiation should be evaluated in the volume of the deposition area in the absorber layer. By using the OK1 code with some corrections, the non-uniformityof heavy-ion beam irradiation for the different ion beams on two kinds of targets were evaluated in 12-, 20-, 60- and 120-beam irradiation schemes. The root-mean-square (RMS) non-uniformity value becomes σRMS= 8. 39% in an aluminum mono-layer pellet structure and σRMS= 6.53% in a lead-aluminum layer target for the 12-uranium-beam system. The RMS non-uniformity for the lead-aluminum layer target was lower than that for the mono-layer target. The RMS and peak-to-valley (PTV) non-uniformities are reduced with the increase in beam number, and low at the Bragg peak layer.     

Complexity And Availability for Fusion Power Plants: The Potential Advantages of Inertial Fusion Energy

Probably the single largest advantage of the inertial route to fusion energy (IFE) is the perception that its power plant embodiments could achieve acceptable capacity factors. This is a result of its relative simplicity, the decoupling of the driver and reactor chamber, and the potential to employ thick liquid walls. We examine these issues in terms of the complexity, reliability, maintainability and, therefore, availability of both magnetic and inertial fusion power plants and compare these factors with corresponding scheduled and unscheduled outage data from present day fission experience. We stress that, given the simple nature of a fission core, the vast majority of unplanned outages in fission plants are due to failures outside the reactor vessel itself. Given we must be prepared for similar outages in the analogous plant external to a fusion power core, this puts severe demands on the reliability required of the fusion core itself. We indicate that such requirements can probably be met for IFE plants. We recommend that this advantage be promoted by performing a quantitative reliability and availability study for a representative IFE power plant and suggest that databases are probably adequate for this task.     

Vibration-RF Control of Superconducting-Helix Resonators for Heavy-Ion Acceleration

An electronic system for the control of the effects of RF frequency oscillations caused by mechanical vibrations in a superconducting helix are described. A combination of frequency modulation and amplitude modulation is used to lock the phase of a self-excited accelerating structure to that of a controlling master oscillator. The system has been used successfully during beam acceleration with a superconducting helix.     

Development of synchrotron control for Heavy-Ion Medical Accelerators

The power supplies for the main bending and quadrupole magnets of the Heavy-Ion Medical Accelerator (HIMAC) in Chiba are controlled by preset current and voltage patterns, which are created by a pattern-creation program. It has been observed that a deviation between the preset current and the actual one becomes very large when newly created patterns are applied to the power supplies. This deviation is attributed to the incorrect parameters used for calculations of the voltage pattern in the pattern-creation program. In order to reduce the deviation, we have analyzed the values of resistance and inductance using the actual data of the current and voltage patterns. As a result, more than 10% difference was found between the conventional and newly calculated parameters. By applying the new parameters to the pattern-creation program a reduction of the deviation was confirmed.     

Development and Operation of a Prototype Superconducting Linac for Heavy-Ion Acceleration

A prototype superconducting-helix accelerator is described and design considerations are discussed. The results obtained during 120 hours of beam acceleration are given. These include a wealth of practical engineering experience, the demonstration of stable operation with external phase control, and measurements of various kinds of accelerator-physics data.     

Photon Induced Reaction Cross-Section Calculations of Several Structural Fusion Materials

In this paper; photo-neutron cross-sections have been computed for ²⁷Al, ^28,29Si, ⁵²Cr, ^54,56Fe isotopes by using nuclear reaction codes TALYS 1.6 and EMPIRE 3.1 with different level density models. Constant Temperature Fermi Gas, Back Shifted Fermi Gas and Generalized Superfluid Models have been employed from TALYS 1.6 whereas Generalized Super Fluid Model was the only model employed from EMPIRE 3.1 reaction codes. Obtained results have been analyzed with experimental values taken from the EXFOR database.     

The Future Potential of Nuclear Power: Fission and Fusion

A comparison is made between fission and fusion as potential future power sources for mankind. Fission is seen to be less complex, but fusion is seen to be environmentally more benign.     

重离子微米孔膜防尘口罩滤芯的研制

本文以重离子微孔膜作为主要过滤材料,研制出一款梳格结构的新型防尘口罩滤芯。经国家权威机构测试,该口罩滤芯过滤效率为99.7%,达到国家标准GB 2626-2006《呼吸防护用品--自吸过滤式防颗粒物呼吸器》KN95的标准;呼吸阻力小于180 Pa,低于国家标准350 Pa。     

Power and Sizes of Tokamak Fusion Neutron Sources with NBI-Enhanced Reaction Rate

Steady state tokamak with deuterium–tritium plasma is considered as a basis for fusion neutron source for a hybrid fusion–fission reactor. Prototypes of such a system can be developed on the basis of the present day tokamaks as the plasma power gain factor Q ~ 1 is required for hybrid applications. Significant population of fast ions can be supported by a powerful neutral beam injection heating in regimes with Q ~ 1. The reaction rate for fast ions greatly exceeds the rate for thermal Maxwellian ions. The possible ranges of parameters are discussed for medium size tokamaks with minor plasma radius a = 0.5–1 m. Power and sizes of the neutron source are determined by the value of the injection energy. Power gain Q ≈ 1 can be achieved with injection energy of deuterium about 130 keV and tritium energy about 200 keV. Neutron power of 30–40 MW can be realized with a ≈ 1 m, and about of few megawatts with a ≈ 0.5 m.     

Studies on p+6Li Fusion Reaction using 3-Parameter Model

The 3-parameter model introduces 3 parameters (radius of a square nuclear potential well, the real part and the imaginary part of the nuclear potential depth) to describe the low energy behavior of the fusion cross-section for light nuclei. It has been justified by the experimental data from the National Nuclear Data Center (NNDC) for 3 major fusion reactions (d?+?T, d?+?D, and d?+?³He). In the present paper this 3-parameter model has been extended to p+⁶Li fusion reaction. It agrees with the fusion cross-section data from NNDC again. Moreover it is able to calculate the astrophysical S-factor with an electron screening potential for p+⁶Li fusion reaction as well. As a development of the 3-parameter model, the necessary condition for a low energy resonant tunneling through Coulomb barrier is derived. It reveals further the possibility of resonant tunneling at very low energy for p+⁶Li system.     

Mechanisms for Rapid Electron Transfer in Ionic Solids Following Multiple Ionization by Heavy-Ion Impact

Systematic measurements of the spectra of fluorine K? x-rays produced by the bombardment of alkali and alkaline earth fluorides with 2-MeV/amu ions ranging from He to Ar have given new information on the mechanisms for rapid electron transfer within the K-hole lifetime (~10-13sec.). Spectra obtained with He ions provide clear evidence of the occurrence of resonant electron transfer (RET) following 1s2p ionization of F- in the compounds KF and SrF2. Calculations employing a point-charge model support the conclusion that the anomalously low KL1 x-ray satellite intensities observed for these two compounds are the result of a resonant exchange of an electron between the outermost p level of the metal ion and the 2p level of the fluorine ion. Such a transfer mechanism requires a close match between the energies of the two levels involved. Recent measurements using 22-MeV carbon ions have revealed that the KL2 satellite intensity in CaF2 is much lower than that displayed by any of the other group II fluorides, thereby suggesting RET also occurs in association with this double L-hole state. When high states of ionization are produced, rapid electron transfer to the fluorine L-shell becomes highly probable even in the absence of level matching. The mechanism for this probable involves collision induced transitions from the fluorine 2p band. At the same time, population of the M-shell levels of the ionized fluorine occurs, as is evidenced by the observation of large x-ray energy shifts and intense K? hypersatellite structure.