Design of a 1-MW, CW coaxial gyrotron with two gaussian beam outputs

The design of a 170 GHz, 1 MW-CW gyrotron for electron cyclotron heating of nuclear fusion plasmas is presented. The designed gyrotron incorporates a coaxial cavity to reduce mode competition, and a coaxial electron gun to support the cavity inner conductor. A new mode converter splits the generated wave into two beams and radiates them in different directions. The radiated beams are transmitted to two output windows through two mirror systems, being transformed into Gaussian-like beams. A single-stage depressed collector improves the overall efficiency of the gyrotron and reduces the heat flux to the collector surface.     

CT-6B托卡马克的电子迴旋波加热实验

分别使用频率为34.34GHz和20.1GHz的迴旋管系统从外侧和顶端注入微波,对CT-6B托卡马克等离子体加热,均观察到明显的加热效果。分析表明两者有不同的加热机制。前者主要属于O模的共振加热;后者为X模的非共振-高密度加热,其机制可能来源于高密度截止层附近的非线性现象。在两种实验中,都观测到称为二次加热的非线性加热现象。它们可能分别来自不同的物理机制。     

kW级光纤耦合输出二极管激光器模块

基于二极管激光器mini-bar的光纤耦合方式是一种降低耦合系统成本并提高整体转换效率的方法, 为此,采用40片封装在铜微通道冷却器上的连续60 W二极管激光器mini-bar组成空间叠加阵列,作为耦合光源,采用非球面柱透镜及柱透镜阵列对mini-bar叠阵进行了快轴与慢轴的准直,实现了两列叠阵的激光束沿快轴方向的空间合成以提高叠阵激光束的填充因子,合成后的激光束可以耦合进入芯径为800 m、数值孔径为0.22的光纤。测试结果表明,光纤耦合模块输出功率最高为1360 W,整体光光效率58%,光纤端面的功率密度达到1.73105 W/cm2。     

Optimization of the design for beamline with fast polarization switching elliptically polarized undulators

Fast switching of X‐ray polarization with a lock‐in amplifier is a good method for acquiring weak signals from background noise for X‐ray magnetic circular dichroism (XMCD) experiments. The usual way to obtain a beam with fast polarization switching is to use two series of elliptically polarized undulators (tandem twin EPUs). The two EPUs generate two individual beams. Each beam has a different polarization and is fast switched into the beamline. It is very important to ensure that the energy resolution, the flux and the spot size at the sample of the two beams are equal in XMCD experiments. However, it is difficult in beamline design because the distances from the two EPUs to the beamline optics are different and the beamline is not switchable. In this work, a beamline design without an entrance slit for fast polarization switching EPUs is discussed. The energy resolution of the two beams can be tuned to be equal by minor rotation of the optics in the monochromator. The flux of the two beams can be balanced through separation blades X, Y in the exit slit, and by adjusting the position of the X blades along the beam. The spot size of the two beams can be adjusted to be equal by shifting the sample as well.     

Formation of desired concentration profiles of embedded atoms and radiation-induced defects by using monochromatic fast ion beams

A method for the formation of fast ion beams with an energy spectrum providing a desired profile of embedded atoms and radiation-induced defects in the sample is suggested. A rigorous mathematical analysis of the profiles of film energy absorbents that produce light-and heavy-ion beams with a necessary energy spectrum from fast monochromatic beams is performed.     

基于层状固定光折变全息的单块光学修正的gamma网络

提出一种利用ＣＯ２激光热固定的层状光折变体相位全息在一块晶体内实现一个固态微小化光学系统的方法理论分析证明利用双面线状激光加热的方案可以形成适合热固定的层状温度分布，初步实验中，在一块ＬｉＮｂＯ３光折变晶体中建立了单级的修正的ｇａｍｍａ网络，由此表明把一个复杂的光学系统微小化组装在单块的晶体中是可行的。     

Review of Japanese fusion program and role of inertial fusion

The high compression of 600 times liquid density and the recent fast heating of a compressed core to 1-keV temperature have provided proof-of-principle of the fast ignition concept, and these results have significantly contributed to approve first phase of the Fast Ignition Realization EXperiment (FIREX) project. The goal of FIREX-I is to demonstrate fast heating of a fusion fuel up to the ignition temperature of 5–10 keV. Although the fuel size of FIREX-I is too small to ignite, sufficient heating will provide the scientific viability of ignition-and-burn by increasing the laser energy thereby the fuel size. Based on the result of FIREX-I, the decision of the start of FIREX-II to achieve ignition-and-burn can be made. The FIREX program is under the collaboration of the Institute of Laser Engineering and the National Institute for Fusion Science.     

双频激光在不均匀等离子体中的耦合

本文研究了具有不同频率的两束激光在不均匀等离子体拍频共振点的耦合系数,计算了该系数对于等离子体拍频波加热的影响以及它对于双频光束频率比和等离子体定标长度的依赖关系。 关键词：     

Generation of neutrons at the relaxation of fast deuterons in deuterium matter

We analyze the fusion process involving two deuterium nuclei in the case of deceleration of a fast deuteron with an energy of approximately 100 keV located in a deuterium target. We calculate the probability ω _fus(ε) of generating a neutron by a fast deuteron with an initial kinetic energy ε during its deceleration. The mean free path of fast deuterons with respect to their relaxation is found for various deuterium targets. The data are analyzed for neutron generation in deuterium cluster beams under laser irradiation. The method of neutron generation in the collision of two deuterium cluster beams is suggested. The text was submitted by the author in English.     

CO2激光局域热固定光折变全息的一种新方法

提出用ＣＯ２激光加热后记录固定的方案对ＬｉＮｂＯ３晶体中的全息进行实时实地局域热固定。通过加载绝热体,利用连续激光加热晶体全部范围至接近２００℃,停止加热开始记录,到该区域温度降屋１００℃时,将固定一个体全息。文中给出了热传导模型及其数值解。由得到的初步结果参数进行了一系列实验。实验结果显示,管种方案可成功地对光折变全息进行实时实时局域热固定,并且具有温度更均匀的特点,所固定的全息质量有较大改善。     

Development of the fast arcing protection for ECRH system on the HL-2A tokamak

1 Introduction A series of engineering tests and physical experiments,including ECRH[1],was carried out on the HL-2A tokamak in 2005.A fast arcing protection system[2] was developed to ensure operating of ECRH facilities[3],especially the gyrotron,against arcing in the transmission line.     

Fast heating of cylindrically imploded plasmas by petawatt laser light

We produced cylindrically imploded plasmas, which have the same density-radius product of the imploded plasma rhoR with the compressed core in the fast ignition experiment and demonstrated efficient fast heating of cylindrically imploded plasmas with an ultraintense laser light. The coupling efficiency from the laser to the imploded column was 14%-21%, implying strong collimation of energetic electrons over a distance of 300 microm of the plasma. Particle-in-cell simulation shows confinement of the energetic electrons by self-generated magnetic and electrostatic fields excited along the imploded plasmas, and the efficient fast heating in the compressed region.     

高功率高效率光纤耦合半导体激光模块研制

采用光束整形和空间合束的方法,研制出高功率、高效率多阵列光纤耦合半导体激光模块。将波长为976nm连续工作的5个标准半导体阵列,通过对快轴进行准直和快慢轴光束旋转的方式进行光束整形,准直后进行空间合束,经耦合透镜聚焦,耦合入芯径400μm、数值孔径0.22的光纤。测量结果显示:光纤的出光功率最大可达到327 W,光纤耦合效率大于93.6%。     

A new method for the production of atomic beams of highly refractory elements and first atomic beam magnetic resonances in Ta181

A new universal method for the production of atomic beams of highly refractory elements has been developed. The beams of free atoms are produced by locally heating a small area on a target consisting of the material to be evaporated. The local heating is achieved via the focussed electron beam of a commercial electron gun. The atomic beams so obtained are suitable for studying hyperfine structures by the atomic beam magnetic resonance method. The first observedrf resonances in the ground state⁴ F _3/2 and the first excited state⁴ F _5/2 of Ta¹⁸¹ are reported.     

Performance comparison of self-focusing with 1053- and 351-nm laser pulses

Hole boring characteristics of laser beams are studied using two different laser wavelengths in preformed plasmas with overdense regions. We have shown that a whole beam self-focusing is created in plasma with a considerable density scale length using a 1 microm wavelength laser. The whole beam self-focusing of this type could be used for guiding the ultrahigh intense laser pulse to a highly compressed core for studying the feasibility of a fast ignitor. There is a clear difference in the hole-boring characteristics between two laser wavelengths at 1053 and 351 nm, both in the experiment and the simulation. Using the third-harmonic laser, a whole beam self-focusing is never created. The 351-nm laser beam broke up into filaments resulting in plasma jets observed in our interferogram.     

高功率高效率光纤耦合半导体激光模块研制

采用光束整形和空间合束的方法,研制出高功率、高效率多阵列光纤耦合半导体激光模块。将波长为976 nm连续工作的5个标准半导体阵列,通过对快轴进行准直和快慢轴光束旋转的方式进行光束整形,准直后进行空间合束,经耦合透镜聚焦,耦合入芯径400 m、数值孔径0.22的光纤。测量结果显示：光纤的出光功率最大可达到327 W,光纤耦合效率大于93.6%。     

两路120 W固体激光高光束质量相干合成

通过主动相位控制实现了两路固体激光器的高光束质量相干合成输出,总输出功率达到240 W。建立了两路120 W板条激光放大器,通过光束整形获得了高光束质量方形光斑,并实现了高占空比光束拼接,填充因子高于92.4%。研制了光轴一致性探测与控制系统,采用基于压电陶瓷的快反镜实现了光轴的高精度闭环控制,两束激光光轴一致性优于2 rad（RMS）。设计了基于现场可编程门阵列（FPGA）的相位探测与控制系统,用随机并行梯度下降算法（SPGD）锁定了两束激光的活塞相位。相位闭环后,远场光斑峰值提高到开环状态的1.7倍,为理想值的84%。合成光束主瓣包含67%的激光总能量,光束质量（BQ）为1.1。     

两路120 W固体激光高光束质量相干合成

通过主动相位控制实现了两路固体激光器的高光束质量相干合成输出,总输出功率达到240W。建立了两路120W板条激光放大器,通过光束整形获得了高光束质量方形光斑,并实现了高占空比光束拼接,填充因子高于92.4%。研制了光轴一致性探测与控制系统,采用基于压电陶瓷的快反镜实现了光轴的高精度闭环控制,两束激光光轴一致性优于2μrad(RMS)。设计了基于现场可编程门阵列(FPGA)的相位探测与控制系统,用随机并行梯度下降算法(SPGD)锁定了两束激光的活塞相位。相位闭环后,远场光斑峰值提高到开环状态的1.7倍,为理想值的84%。合成光束主瓣包含67%的激光总能量,光束质量(BQ)为1.1。     

快波少数离子加热

对快波少数离子加热的机理进行了比较详细的讨论.通过射线轨迹算法对两种离子的等离子体快波加热进行了数值模拟,并给出了两种离子不同浓度比的计算结果.     

激光驱动强流电子束产生和控制

在惯性约束聚变(ICF)电子束快点火物理方案中,需要超强拍瓦激光脉冲驱动MeV能量的强流电子束,并沉积数十kJ能量到压缩氘氚芯区。强流电子束的束流品质是影响点火成功的关键因素之一,为深入了解强流电子束产生物理过程,研制成了三维高性能、适应上万CPU核规模的并行粒子模拟程序,并开展了大规模数值模拟研究,探索了强流电子束的产生机制和输运规律。回顾了近几年来快点火研究团队围绕强流电子束产生和控制开展的研究,介绍了导致束流品质差的两大物理原因:预等离子体效应和束流不稳定性磁场的随机散射。针对这两个物理原因,提出了四种提高强流电子束品质的方法:(1)双层金锥靶减弱预等离子体的负面效应;(2)输运丝产生环向磁场准直强流电子束;(3)外加磁场导引强流电子束提高耦合效率;(4)抑制束流不稳定性以降低随机磁场对电子束流的散射。