EAST装置微波反射成像系统光学性能评测

用宽为1cm的金属反射平面对EAST装置上96道(极向12道×径向8道)微波成像反射计的前端接收光路的道间距和探测光斑半径进行了测试,结果与仿真结果较为一致。用极向旋转的金属轮面作为反射面,研究了非理想光学条件下反射面旋转所引入的多普勒频移,结果与模拟值吻合。     

Z箍缩动态黑腔冲击波辐射图像诊断

在“聚龙一号”装置上开展了单层钨丝阵加载重泡沫的动态黑腔实验, 初步研究了Z 箍缩动态黑腔中冲击波传播和黑腔形成的物理过程. 获得了冲击波辐射环的演化图像, 分析了丝阵等离子体与泡沫的作用过程及动态黑腔内的辐射特性. 测得冲击波的向心传播速度为(14.2±1.7) cm/μs, 冲击波平均宽度为0.8-0.9 mm. 冲击波辐射环的发光强度沿角向分布的标准偏差约为±10%, 中心黑腔区的标准偏差约为±4.2%.     

Coupled channel T-operator equations with connected kernels: (II). N coupled two-body channels

A time-independent theory of rearrangement collisions involving transitions between two-body states is presented. It is assumed that the system of interest consists of particles that may be partitioned into two-body systems in N ways, including interchanges of particle labels without changing the kind of channel. An infinite family of sets of N coupled T-operator equations is derived by use of the channel coupling array, as in previous work on the three-body problem. Specialization to the channel-permuting arrays guaranteeing connected (N?1)th iterates of the kernel of the coupled equations is made in the N-channel case (N > 3) and the nature of the solutions to the coupled equations is discussed. Various approximation schemes to be used with numerical calculations are suggested. Since the transition operators for all rearrangement channels are coupled together, no problems concerning non-orthogonality of the eigenstates of different channel Hamiltonians are encountered; also the presence of the outgoing wave boundary condition in all channels is made explicit. The close resemblance of the equations in matrix form to those of one-channel scattering is exploited by introducing Møller wave operators and associated channel scattering states, an optical potential formalism that leads to rearrangement channel optical potential operators, and a variational formulation of the coupled equations using a Schwinger-like variational principle. A brief comparison with other many-body formalisms is also given.     

A flexible 9-channel coil array for fast 3D MR thermometry in MR-guided high-intensity focused ultrasound (HIFU) studies on rabbits at 3 T

Signal-to-noise ratio (SNR) is a critical factor in MR-guided high-intensity focused ultrasound (HIFU) for local heating, which can affect the accuracy of temperature measurement. In order to achieve high SNR and higher temporal resolution, dedicated coil arrays for MR-guided HIFU applications need to be developed. In this work, a flexible 9-channel coil array was designed, and constructed at 3 T to achieve fast temperature mapping for MR-guided HIFU applications on rabbit leg muscle. Coil performance was evaluated for SNR, and parallel imaging capability by in-vivo studies. Compared to a commercially available 4-channel flexible coil array, the dedicated 9-channel coil array has a much higher SNR, with at least a 2.6-fold increment in the region of interest (ROI). The inverse g-factors maps demonstrated that the dedicated 9-channel coil array has a better parallel imaging capability than the Flex Small 4. With accelerations normal to the array direction, both coil arrays showed much higher g-factors than those of accelerations along the array direction. Room temperature mapping was implemented to evaluate the temperature measurement accuracy by in-vivo experiments. The precisions of the 9-channel coil, ±0.18 °C for un-acceleration and ± 0.56 °C for acceleration at R = 2 × 2, both improved by an order of magnitude than these of the 4-channel coil, which were ± 1.45 °C for un-acceleration and ± 3.52 °C for acceleration at R = 2 × 2. In the fast temperature imaging on the rabbit leg muscle with heating, a high temporal resolution of 3.3 s with a temperature measurement precision of ±0.56 °C has been achieved using the dedicated 9-channel coil. This study demonstrates that the dedicated 9-channel coil array for rabbit leg imaging provides improved performance in SNR, parallel imaging capability, and the accuracy of temperature measurement compared to a commercial 4-channel coil, and it also achieves fast temperature mapping in practical MR-guided HIFU applications.     

丝阵Z箍缩实验1维X光辐射功率分布

 在Angara-5-1联合实验中，利用条纹像机和光纤阵列实现时间分辨和1维空间分辨，得到了丝阵条纹像，观察到丝阵负载箍缩区X光辐射的1维轴向空间分布信息随时间的演化过程，考察了内爆的同步性和均匀性。通过对比不同结构负载内爆等离子体X光1维时空分布信息，发现由于内层等离子体对磁流体瑞利-泰勒不稳定性的抑制作用，(40+20)根双层钨丝阵比60根单层钨丝阵的内爆轴向同步性好，产生的X光辐射功率高；由于负载存在弯曲、断丝、扭曲等现象，(60+30)根双层钨丝阵比90根单层钨丝阵的轴向同步优势不明显；轴向同步性好与辐射功率高之间存在相关性；辐射波形前沿较快时，X光功率较高。     

EAST高时空分辨极向弯晶谱仪系统的升级及初步实验结果

为了拓宽等离子体参数测量范围,对EAST极向弯晶谱仪(PXCS)进行了升级改造。配合高通量大面积水冷固体探测器,提高了极向弯晶谱仪系统的光子计数率、时间分辨率、空间探测范围以及长时间运行稳定性,并在EAST装置上成功运行。实验结果表明,升级后的谱仪获得了高信噪比的类氦氩离子的母线及其一系列伴线谱,通过光谱拟合分析给出了等离子体温度时间演化及其剖面信息,测量结果与切向弯晶谱仪的数据一致,验证了极向弯晶谱仪的升级结果和数据测量的可靠性,并且在EAST长脉冲实验运行也能够稳定地提供全时间的参数分布。     

用塞曼双频激光器作光源的一种新颖长扫描表面的仪器设计

本文报道一套光学结构用于同步辐射反射镜表面轮廓高精度大面积的测量。采用了光学外差测量与接收技术,以伺服聚焦双折射透镜组分离“o”光与“e”光的聚焦区域,并再共轴组合比较其相位差,从而获得表面起伏的误差值。线性运动的测量工作台使镜面可测量范围从数微米到一米,而最小起伏量及曲率可达很高的测量精度。     

Real-time adjustment of optical transmitter by laser beam parameter measurement based on two linear array CCD scanning imaging

In this paper, we present a real-time measurement and adjustment method, based on scanning imaging, for optical transmitter which emits 90° × 2° linear laser beam. This novel optical arrangement consists of an area array CCD and two linear array CCDs. According to the relationship between the positions, angles of transmitter optical components and the beam parameters of emergent laser, the system can help us to decide the real-time adjustment of optical transmitter by measuring the related beam parameters. In order to improve the measurement speed, avoid occlusion and ensure simultaneous measurement, the two linear array CCDs are placed at near field, far field and separated by a definite angle to acquire the beam intensity distribution through suitable nonlinear correction during the process of scanning. After a complete scanning, the beam parameters and the spot image are acquired by continuous measurement. The proof-of-principle experiments showed that the measurement results were in agreement with the analysis. The presented method was applied to direct fast adjustment for higher quality on the assembly of the optical transmitter. The presented procedure is highly advantageous for diverse laser beam emitted from the optical transmitter, such as elliptic, linear and so on.     

Experimental investigation of supersonic radiation propagation in low-density plastic and copper-doped foams

1 Introduction The investigation of supersonic radiation wave transporting in low density foam pro-duced by thermal radiation is of crucial importance in inertial confinement fusion (ICF) research[1]. When the intense radiation flux is incident in the media, first, a supersonic heat wave is formed which propagates into the undisturbed material. In time, due to the increasing mass of heated material, it slows down and is overtaken by a shock wave,thus becoming of the ablative type. Normally, …     

用于真空弧等离子体放电阴极温度场测量的多光谱高温计

阴极表面温度是真空弧等离子体放电过程中一个重要参数,对真空弧等离子体的形成、电极腐蚀预测、热传导以及离子源的寿命都有重要影响。真空弧离子源的阴极具有目标小,放电过程快等特点,其温度的测量,对于时间分辨率和空间分辨率要求都很高,阴极表面温度的测量技术的欠缺,使得仅靠理论解析获得的结果难以得到验证。并且等离子体放电过程中测量仪器极易受到弧光的影响,如何避免放电过程中等离子体的辐射也是采用辐射法测量阴极表面温度要考虑的问题。这无疑给其温度场的测试研究带来困难。针对脉冲真空弧等离子体开展阴极表面温度测试实验有着重要意义,在分析了真空弧等离子体放电特性以及背景辐射特性和等离子体放电阴极测温的实际需求,本文基于高速CCD相机研制了一种新型的多光谱高温计。该高温计采用单色高速CCD相机,主要避免RGB彩色相机不能完全滤除背景辐射的弧光。为使用单色CCD相机实现多光谱辐射测温,设计了高温计的光学系统,该系统采用4孔径分光系统。将4种不同波长的滤光片嵌入到1个滤光片中。该研究设计的高温计可用于2 000~6 000 K的等离子体温度测量。并在中国工程物理研究院电子工程研究所进行现场测试,测试过程中将研制的高温计,通过外部触发形式对等离子体放电过程进行跟踪拍摄,高温计完全拍摄到等离子体放电过程。利用真空弧等离子体金属电极阴极放电的实测数据对高温计进行了验证。实验结果表明,设计的新型多光谱高温计能够用于测量真空弧等离子体放电时阴极温度场信息,测量的温度值低于放电电极的沸点温度,与等离子体放电过程中出现气化现象相符,说明高温计测的是等离子体放电阴极的温度。     

一种使用线阵型CCD实现高精度二维位置测量的方法

介绍了一种使用ＣＣＤ测量位置的方法。与其它ＣＣＤ位置测量系统不同，通过设计一个特殊的光学系统，实现了使用两个线阵型ＣＣＤ进行高精度二维位置坐标测量。文中对该光学系统进行了误差分析，证实该方法具有很高的测量精度。该二维位置测量方法具有一些突出的优点：系统响应速度快，可以对动态目标进行测量；测量精度高；制造成本低。上述特点使它在工业制造领域内有着广阔的应用前景。     

Optical diffraction tomography microscopy with transport of intensity equation using a light-emitting diode array

Optical diffraction tomography (ODT) is an effective label-free technique for quantitatively refractive index imaging, which enables long-term monitoring of the internal three-dimensional (3D) structures and molecular composition of biological cells with minimal perturbation. However, existing optical tomographic methods generally rely on interferometric configuration for phase measurement and sophisticated mechanical systems for sample rotation or beam scanning. Thereby, the measurement is suspect to phase error coming from the coherent speckle, environmental vibrations, and mechanical error during data acquisition process. To overcome these limitations, we present a new ODT technique based on non-interferometric phase retrieval and programmable illumination emitting from a light-emitting diode (LED) array. The experimental system is built based on a traditional bright field microscope, with the light source replaced by a programmable LED array, which provides angle-variable quasi-monochromatic illumination with an angular coverage of ±37 degrees in both x and y directions (corresponding to an illumination numerical aperture of ∼0.6). Transport of intensity equation (TIE) is utilized to recover the phase at different illumination angles, and the refractive index distribution is reconstructed based on the ODT framework under first Rytov approximation. The missing-cone problem in ODT is addressed by using the iterative non-negative constraint algorithm, and the misalignment of the LED array is further numerically corrected to improve the accuracy of refractive index quantification. Experiments on polystyrene beads and thick biological specimens show that the proposed approach allows accurate refractive index reconstruction while greatly reduced the system complexity and environmental sensitivity compared to conventional interferometric ODT approaches.     

一种高速多通道光纤阵列光开关

为了对短时间大视场一维光强信息进行采集,采用编码转换技术和自聚焦透镜矩形阵列设计了光开关,用小口径电光晶体实现了大视场的测量.采用MOS管级联的高压同步电路,使得系统具有结构紧凑、性价比高、寿命长等优点.实验结果表明:开关选通时间100±5 ns,前后沿小于25 ns,消光比1 100∶1.     

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利用EAST装置单道远红外HCN激光干涉仪测量了等离子体中心道(R=1.82m)线平均电子密度。通过充气加料连续提升主等离子体密度,首次在EAST装置上观察到偏滤器等离子体的三种不同状态：低再循环(偏滤器靶板处等离子体温度较高,密度较低),高再循环(偏滤器靶板处等离子体温度较低,密度较高)和脱靶(偏滤器靶板处等离子体温度和密度都很低)等离子体状态。分析了EAST偏滤器在这三种不同状态下的物理现象。     

EAST远红外激光干涉仪与密度爬升实验研究

利用EAST装置单道远红外HCN激光干涉仪测量了等离子体中心道(R=1.82m)线平均电子密度。通过充气加料连续提升主等离子体密度,首次在EAST装置上观察到偏滤器等离子体的三种不同状态：低再循环(偏滤器靶板处等离子体温度较高,密度较低),高再循环(偏滤器靶板处等离子体温度较低,密度较高)和脱靶(偏滤器靶板处等离子体温度和密度都很低)等离子体状态。分析了EAST偏滤器在这三种不同状态下的物理现象。     

All-optical confinement of ultracold plasma with resonant ions

The solution of the problem of all-optical (nonmagnetic) confinement of ultracold electron-ion neutral plasma based on selective action on plasma ions with quantum transition J=1→J=0 of so-called rectified radiation forces in a strong nonmonochromatic light field is suggested. The presented scheme of the three-dimensional dissipative optical trap for plasma allows one to obtain long-lived ultracold plasma with controlled characteristics. The lifetime of the ultracold plasma in such a trap may exceed considerably (by orders of magnitude) the time of free plasma expansion and the lifetime in the (earlier proposed) optical molasses for the ultracold plasma.     

强光一号Z箍缩实验研究

 在强光一号装置驱动电流峰值1.4~2.1 MA、上升时间80~100 ns条件下,研究了喷Kr气、喷Ne气、W丝阵和Al丝阵负载Z箍缩等离子体的辐射特性和聚爆过程。实验研究中,用分压器和两个罗戈夫斯基线圈分别测量二极管的电压和流过负载的电流波形,用过滤型X射线二极管和100~1 400 eV平能谱响应闪烁探测器测量X射线时间谱,用镍薄膜量热计测量X射线总能量,用纳秒时间分辨软X射线图像诊断系统记录了Z箍缩的聚爆过程,用时空分辨的椭圆弯晶谱仪诊断了Z箍缩等离子体产生的keV级特征X射线的能谱分布。其中,喷Kr气负载的X射线辐射总能量大于60 kJ,峰值功率约1.7 TW,总能量转换效率可达23%;W丝阵负载的辐射总能量大于30 kJ,峰值功率约1.30 TW,总能量转换效率约为12.5%;喷Ne气负载的keV级辐射总能量5.6 kJ,峰值功率约256 GW,能量转换效率可达2%; Al丝阵负载的keV级辐射总能量2.3 kJ,峰值功率约94 GW,能量转换效率可达0.8%。喷气负载在Z箍缩聚爆过程中存在“拉链”现象,丝阵负载在Z箍缩聚爆过程中存在先驱现象。     

同步辐射X射线荧光光谱国内外研究进展

同步辐射光源是带电粒子在加速器储存环中以接近光速的速度运动时,沿轨道切线方向发射出的辐射,同步辐射X射线荧光分析（SR-XRF）是以同步辐射X射线作为激发光源的X荧光光谱分析技术。同步辐射X射线荧光分析包括了用于微区及微量元素分析的同步辐射XRF、用于表面及薄膜分析的同步辐射全反射X射线荧光（SR-TXRF）以及用于三维无损分析的同步辐射X射线荧光扫描和成像方法（如X射线荧光CT、X射线荧光全场成像、共聚焦X射线荧光和掠出射X射线荧光等）。X射线荧光光谱法通过测量元素的特征X射线发射波长或能量,识别元素,该方法首先通过测量发射的特征线强度,然后将该强度与元素浓度联系起来,对给定元素进行量化分析。X射线荧光光谱技术可以进行多元素同时分析,同步辐射X射线荧光谱亮度高,可调谐,相干性、准直性及偏振性好,可以用于分析样品元素的含量和空间分布。近些年来随着新光源技术的使用、分析软件的更新换代和定量分析方法的发展,对同步X射线荧光光谱分析产生了极大促进,采用新型X射线光学元件和探测器,能极大提升分辨率和探测效率,促进相关学科应用的发展。介绍了近几年来国内外同步辐射X射线荧光光谱分析技术及其应用发展状况,给出了国内外比较典型的同步辐射X射线荧光光谱分析光束线站最新技术方面的发展概况,并列举了一些典型应用成果,例如在生物医学、环境科学、地质考古、材料科学和物理及化学等领域的应用。对于本领域及相关领域的专家学者了解国内外同步辐射技术发展现状、应用研究成果具有一定的参考意义。     

常压下低温等离子体光辐射特性测量

采用常压空气辉光放电(APGD)技术在自行设计的电极板表面产生出一薄层低温等离子体,并利用光谱诊断光学系统对所产生的等离子体进行光辐射特性实验测量;实验获取了几种电极板在几个不同加载功率下的辐射光谱,并对光谱的辐射强度进行平均化处理分析。分析结果表明此沿面APGD的光辐射强度与加载功率之间存在线性增加的关系,且随电极板静态电容的增加而增强。该方法可以为控制APGD等离子体的产生量提供一种简便可行的途径。     

Development of One-dimensional Fiber-Optic Radiation Sensor for Measuring Dose Distributions of High Energy Photon Beams

The purpose of this study was to develop a method for measuring the one-dimensional dose distribution of a high-energy photon beam using a miniaturized high-resolution fiber-optic radiation sensor array. The measurements were made by thin plastic optical fibers with organic scintillating fiber sensor probes that emit the visible wavelength of light. The scintillating light is guided to a silicon photodiode array by plastic optical fibers in order to convert light output to an electrical signal. The one-dimensional spatial dependence of photon beam is measured by a one-dimensional fiberoptic sensor array in a poly(methyl methacrylate) (PMMA) phantom. It is shown that this fiber-optic radiation sensor has better spatial resolution than a conventional ionization chamber and much less time is required to measure one-dimensional dose distribution in the high radiation fields. The real-time and the high spatial resolution measurements due to the small detector volume make this system suitable for dosimetry in radiation therapy.