本研究项目已获得欧洲研究委员会的资助下在欧盟的第七框架计划（FP7/2007-2013）赠款协议/ ERC N°242710，并额外支援的人类前沿科学计划和埃米诺特计划的德国研究基金会（SCHR 995/2-1）。

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没有利益冲突的声明。

超极化的氙的制备中的关键方面是，包括泵送小区和足够的照明的圆偏振光的细胞与氧气的气体歧管中的杂质。上述的灯泡测试是一个简单的方法来检测有害的氧浓度，同时转印铷。的碱金属，可能会失去其表面有光泽的时间的单元被安装在偏振片。然而，非氧化的Rb的足够的汽化可以减少激光传输（加热新鲜细胞的第一次时，它可能是一个附加的温度增加了约20℃需要启动的汽化过程，一旦监测...

超极化剂的NMR / MRI的应用得到越来越多的关注，因为他们可以在某些情况下，解决了敏感的问题2。目前使用三种主要方法（动态核极化，DNP，仲氢诱导极化，PHIP和自旋交换光抽运燮）的实际光谱成像实验前准备人为地增加核磁共振磁体的自旋群体差异外。在这里，我们描述的燮设定的功能和操作进行了优化，在溶液状态的实验中使用的超极化129 Xe的生产。 的一个重要组成部分，是一种强烈的光源，发射红外光子在795 nm处。激光二极管阵列（LDA）是方便的设备，提供高输出功率&gt; 100 W，在合理的成本。在许多设置中，LDA是发射到光纤中，更多或更少的偏振保持的日E激光光。为了保证足够燮过程，这个椭圆偏振必须将其转换成高纯度的圆极化。在图1和图2所示的偏光光学系统的主要组成部分的，和设置系统的补充电影1中示意性说明。 为圆极化光，我们首先将光纤末端，一个主要的光学扩束（ 例如 ，光纤准直器），以减少功率密度。然后，光穿过偏振分束器立方体，产生直线偏振光。我们可以通过旋转这个立方体确定最佳的剩余极化轴用功率计。最大传输对应于多维数据集的快轴的对齐的情况下，与主要的光的偏振轴。立方体的高消光系数（10万：1或更好）的偏振分量产生了良好的分离。这可通过而旋转，而第一个额外的普通光束的最大传输对准作为分析仪使用的第二束分光器立方体。 一旦已被证实的线性偏振的透射光，设计为795 nm的λ/ 4波片被引入额外的普通光束转换成圆偏振的线性。为了这个目的，波片的快轴的是由45°相对于分束器立方体快轴转动。 （如果需要的话，其线性偏振轴垂直于额外的寻常光束反射的普通光束的圆偏振的可以以类似的方式实现的。） 圆偏振的质量可与第二分束器立方体旋转时，应该得到恒定的传输进行测试。一个二次光学扩束（ 例如，两个镜片在伽利略望远镜配置），然后增加的光束直径，完全我lluminate的玻璃烤箱箱内抽水过程中的细胞。 Rb蒸气在单元格中的激光的吸收进行监测，通过泵送小区后面的销孔在底框：准直器收集的减毒的红外光束，用光学光谱仪进行分析（参见图3，用于泵送单元设置）。 泵送小区甲外侧加热机构部分坐在里面的细胞（ 图4a）的Rb液滴蒸发，并因此使激光吸收。的蒸气的密度可以通过调整各自的PID控制器的加热设定点。高温（约190℃），良好的紧凑型设置，氙气在有限的时间来建立极化。含有氙，N 2和He的气体混合物流经泵送的细胞（ 图3）的激光束方向相反。用激光束对准的外部磁场确保第Ë红外光子只抽一个RB过渡的。电子态的放宽是快速和必须以避免非辐射发射红外光子与“错误”偏振。这里，作为骤冷气体的N 2进场。最终，其Rb系统建立人口过剩之一的接地状态次能级的激光（ 图5），而另一种是连续地耗尽。氙气中的铷原子的紧密联系，以体验转移到触发器过程的氙原子核自旋相互作用的电子自旋极化。 泵送小区流出的超极化气体中含有微量的Rb蒸气冷凝液上的管壁内的低温（类似于图4b）的出口，由于几个厘米， 在体内应用，但是，会需要额外的消除碱金属（ 例如，通过冷阱）而在体外 experime，个核苷酸可以安全地执行与气体当它离开hyperpolarizer。聚四氟乙烯管连接偏振器出口与入口的玻璃装置执行NMR实验测试解决方案。使用质量流量控制器的NMR设置流入量进行调整的Xe。他们通过NMR脉冲序列中的命令被触发。检查实现极化增强后，气体可以被用作一个NMR / MRI造影剂，在溶液状态下实验。 氙具有一定的在水中的溶解度（4.5毫摩尔/ ATM）和其他溶剂。因此，它已经可以在其自己的服务作为造影剂显示的分布的一些液体。然而，它也能够连结NMR活性核，以便获得通过其他惰性气体的分子的特定信息的某些分子。通过提供一个分子溶解的Xe主机，它是可能的，赋予分子特异性的Xe NMR信号。这提供了机会，设计官能造影剂-也被称为生物传感器-时，这样的主机结构靶向绑定到特定的分析物的生物医学的兴趣（ 图6）的单元，其被耦合到。 需要进一步的灵敏度增强MR造影剂（&lt;100μM），低浓度的生物传感器时，应当被检测到。通过化学交换饱和转移（CEST），这样就可以实现。此方法检测的生物传感器间接由破坏的笼中的Xe的磁化和观察的信号改变在溶液中的游离的Xe。由于超极化核的不断更换后约10毫秒，100多到1000细胞核转移到检测池的信息，放大信号CA。 10倍（见电影2）。

<table border="1"><tbody><tr><td> 的试剂的名称 </td><td> 公司 </td><td> 目录编号 </td><td> 评论（可选） </td></tr><tr><td>铷锭</td><td> Sigma-Aldrich公司</td><td> 276332-1G </td><td></td></tr><tr><td> P 4 O 10 </td><td> Sigma-Aldrich公司</td><td> 79610-500G </td><td></td></tr><tr><td>氩</td><td>普莱克斯</td><td></td><td></td></tr><tr><td>氙气</td><td> Sigma-Aldrich公司</td><td> 00472-1EA </td><td></td></tr><tr><td> O 2 </td><td> Sigma-Aldrich公司</td><td> 00476-1EA </td><td></td></tr><tr><td>激光系统</td><td> QPC激光/激光手术</td><td> Brightlock 50 </td><td></td></tr><tr><td>真空系统</td><td>菲佛</td><td> HiCube </td><td></td></tr><tr><td>热电偶</td><td>新港欧米茄</td><td> SA2F-KI-3M </td><td></td></tr><tr><td>硅加热器</td><td>新港欧米茄</td><td> FMA5514 </td><td></td></tr><tr><td>压力传感器</td><td>新港欧米茄</td><td> PR 33X-V-10 </td><td></td></tr><tr><td>流程米</td><td>新港欧米茄</td><td> INFCP-100B </td><td></td></tr><tr><td>质量流量控制器</td><td>新港欧米茄</td><td> MFC </td><td></td></tr><tr><td> PID调节器</td><td>新港欧米茄</td><td> CN7800 </td><td></td></tr><tr><td>控制软件</td><td>新港欧米茄</td><td> DasyLab </td><td></td></tr><tr><td>数据采集</td><td>新港欧米茄</td><td> Daqboard 3000 </td><td></td></tr><tr><td>真空传感器</td><td>欧瑞康</td><td> TTR91 </td><td></td></tr><tr><td>真空控制器</td><td> VACOM </td><td> MVC-3 </td><td></td></tr><tr><td>光束准直器</td><td> Thorlabs公司</td><td> F810SMA-780 </td><td></td></tr><tr><td>偏振光束分光器立方体</td><td> Thorlabs公司</td><td> GL15-B </td><td></td></tr><tr><td> λ/ 4波片</td><td> Thorlabs公司</td><td> WPQ10M-780 </td><td></td></tr><tr><td>扩束镜头</td><td> Thorlabs公司</td><td></td><td></td></tr><tr><td>光纤光谱仪</td><td>海洋光学</td><td> HR4000 </td><td></td></tr><tr><td>光纤</td><td>海洋光学</td><td></td><td></td></tr><tr><td>低压NMR管</td><td> Wilmad </td><td> 513-7LPV - 7 </td><td></td></tr><tr><td> 5mm的NMR管</td><td> Sigma-Aldrich公司</td><td> HX58.1 </td><td></td></tr><tr><td>亥姆霍兹线圈</td><td> Phywe </td><td> 06960-00 </td><td></td></tr><tr><td>熔融硅CA毛细血管</td><td> Polymicro </td><td> TSG 250350 </td><td></td></tr></tbody></table>

hyperpolarized xenon for nmr and mri applications

核磁共振（NMR）光谱和成像（MRI）遭受从固有的低灵敏度，因为即使是强烈的外部磁场产生只有一个小的可检测的净磁化强度的样品在室温下1〜10 T。因此，大多数NMR和MRI的应用程序依赖于分子的检测，在相对 ​​高浓度（ 例如 ，水生物组织成像）或需要过多的采集时间。这限制了我们的能力，利用NMR信号非常有用的分子特异性的许多生化和医疗应用。然而，新方法，在过去的几年中已经出现：所检测到的自旋物种的操纵之前检测到的NMR / MRI磁体内部，可以显着地增加的磁化，并因此允许在低得多的浓度为2分子的检测。 在这里，我们提出了一个方法了氙气的混合气体（2-5％的氙气，10％的极化N 2，平衡）与CA在一个紧凑的设置。 16000倍的信号增强。现代线变窄的二极管激光器允许高效偏振7和立即使用的气体混合物，即使没有的其它组分分离，稀有气体。解释燮设备和决心展示了所取得的自旋极化性能控制的方法。 超极化气体可用于空隙空间成像，包括气体流成像或扩散的研究，在与其他材料的接口8,9。此外，Xe的NMR信号是极为敏感，其分子环境6。这使得使用它作为一个NMR / MRI造影剂，溶解在水溶液中与官能化的分子主机暂时捕获的气体10,11时的选项。直接检测和高灵敏度的间接检测这样的构造中演示了光谱和成像模式。&lt;/ P&gt;

Watch this Scientific Journal Video about Hyperpolarized Xenon for NMR and MRI Applications at JoVE.com

Hyperpolarized Xenon for NMR and MRI Applications

自旋交换光抽（燮）通过超极化的氙的制造进行说明。此方法产生的核自旋极化的Xe-129〜10000倍的增强，和核磁共振光谱和成像中的应用程序。气相和溶液状态的实验。

超极化氙NMR和MRI的应用

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 ...

hyperpolarized-xenon-for-nmr-and-mri-applications

Research

JoVE Journal

Engineering

19.4K 次观看.  Leibniz-Institut für Molekulare Pharmakologie. 自旋交换光抽（燮）通过超极化的氙的制造进行说明。此方法产生的核自旋极化的Xe-129〜10000倍的增强，和核磁共振光谱和成像中的应用程序。气相和溶液状态的实验。

视频: Hyperpolarized Xenon for NMR and MRI Applications

Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 &deg;C), flammable, and volatile organic electrolytes. These organic based electrolyte systems are viable at ambient temperatures, but require a cooling system to ensure that temperatures do not exceed 80 &deg;C. These cooling systems tend to increase battery costs and can malfunction which can lead to battery malfunction and explosions, thus endangering human life. Increases in petroleum prices lead to a huge demand for safe, electric hybrid vehicles that are more economically viable to operate as oil prices continue to rise. Existing organic based electrolytes used in lithium ion batteries are not applicable to high temperature automotive applications. A safer alternative to organic electrolytes is solid polymer electrolytes. This work will highlight the synthesis for a graft copolymer electrolyte (GCE) poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). The conduction mechanism has been discussed and it has been demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence. Batteries containing commercially available LP30 organic (LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) at a 1:1 ratio) and GCE were cycled at ambient temperature. It was found that at ambient temperature, the batteries containing GCE showed a greater overpotential when compared to LP30 electrolyte. However at temperatures greater than 60 &deg;C, the GCE cell exhibited much lower overpotential due to fast polymer electrolyte conductivity and nearly the full theoretical specific capacity of 170 mAh/g was accessed.

Lithium ion batteries employ flammable and volatile organic electrolytes that are suitable for ambient temperature applications. A safer alternative to organic electrolytes are solid polymer batteries. Solid polymer batteries operate safely at high temperatures (&gt;120 &deg;C), thus making them applicable to high temperature applications such as deep oil drilling and hybrid electric vehicles. This paper will discuss (a) the polymer synthesis, (b) the polymer conduction mechanism, and (c) provide temperature cycling for both solid polymer and organic electrolytes.

接枝共聚物固态电解质的锂离子电池的应用

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 ...

科研

工程学

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

一个多腔动态单一酶幻影超极化磁共振剂研究的用途

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 &#60;x/d &#60;25) of a circular jet at Re &#8776; 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.

A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re &#8776; 7,000.

湍流应用三维粒子跟踪测速：一喷流病例

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

Colloidal Synthesis of Nanopatch Antennas for Applications in Plasmonics and Nanophotonics

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic nanoscale patch antennas. This includes a detailed procedure for the fabrication of thin films with a well-controlled thickness over macroscopic areas using layer-by-layer deposition of polyelectrolyte polymers, namely poly(allylamine) hydrochloride (PAH) and polystyrene sulfonate (PSS). These polyelectrolyte spacer layers serve as a dielectric gap in between silver nanocubes and a gold film. By controlling the size of the nanocubes or the gap thickness, the plasmon resonance can be tuned from about 500 nm to 700 nm. Next, we demonstrate how to incorporate organic sulfo-cyanine5 carboxylic acid (Cy5) dye molecules into the dielectric polymer gap region of the nanopatch antennas. Finally, we show greatly enhanced fluorescence of the Cy5 dyes by spectrally matching the plasmon resonance with the excitation energy and the Cy5 absorption peak. The method presented here enables the fabrication of plasmonic nanopatch antennas with well-controlled dimensions utilizing colloidal synthesis and a layer-by-layer dip-coating process with the potential for low cost and large-scale production. These nanopatch antennas hold great promise for practical applications, for example in sensing, ultrafast optoelectronic devices and for high-efficiency photodetectors.

A protocol for the colloidal synthesis of silver nanocubes and fabrication of plasmonic nanoscale patch antennas with sub-10 nm gaps is presented.

在等离子体激元和纳米光子学应用Nanopatch天线的合成胶体

We present a method for colloidal synthesis of silver nanocubes and the use of these in combination with a smooth gold film, to fabricate plasmonic ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

用于光学谐振器和激光应用的聚合物微球的制造

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter metallic implant-related artifacts in MRI, resulting in reduced image quality. Therefore, the MRI suitability of implants in terms of artifact volume, as well as the development of pulse sequences to reduce image artifacts, are becoming more and more important. Here, we present a comprehensive protocol which allows for a standardized evaluation of the artifact volume of implants on MRI. Furthermore, this protocol can be used to analyze the vulnerability of different pulse sequences to artifacts. The proposed protocol can be applied to T1- and T2-weighted images with or without fat-suppression and all passive implants. Furthermore, the procedure enables the separate and three-dimensional identification of signal loss and pile-up artifacts. As previous investigations differed greatly in evaluation methods, the comparability of their results was limited. Thus, standardized measurements of MRI artifact volumes are necessary to provide better comparability. This may improve the development of the MRI suitability of implants and better pulse sequences to finally improve patient care.

We describe a standardized method to evaluate magnetic resonance imaging artifacts caused by implants to estimate the suitability of the implants for magnetic resonance imaging and/or the vulnerability of different pulse sequences to metallic artifacts simultaneously.

评估植入物所引起的 MRI 伪影和脉冲序列易损性评估的协议

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

防结冰用超疏水性金属表面的制备

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Controllable Nucleation of Cavitation from Plasmonic Gold Nanoparticles for Enhancing High Intensity Focused Ultrasound Applications

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) for the controllable nucleation of cavitation in tissue-mimicking gel phantoms. This in vitro protocol was developed to demonstrate the feasibility of this approach, for both enhancement of imaging and therapeutic applications for cancer. The same apparatus can be used for both imaging and therapeutic applications by varying the exposure duration of the HIFU system. For short duration exposures (10 &#181;s), broadband acoustic emissions were generated through the controlled nucleation of inertial cavitation around the gold nanoparticles. These emissions provide direct localization of nanoparticles. For future applications, these particles may be functionalized with molecular-targeting antibodies (e.g. anti-HER2 for breast cancer) and can provide precise localization of cancerous regions, complementing routine diagnostic ultrasound imaging. For continuous wave (CW) exposures, the cavitation activity was used to increase the localized heating from the HIFU exposures resulting in larger thermal damage in the gel phantoms. The acoustic emissions generated from inertial cavitation activity during these CW exposures was monitored using a passive cavitation detection (PCD) system to provide feedback of cavitation activity. Increased localized heating was only achieved through the unique combination of nanoparticles, laser light and HIFU. Further validation of this technique in pre-clinical models of cancer is necessary.

This protocol demonstrates the controllable nucleation of cavitation in gel phantoms, through simultaneous exposure to both near-infrared pulsed laser light and high intensity focused ultrasound (HIFU). The cavitation activity can then be used for enhancing imaging and/or therapeutic uses of HIFU.

等离子金纳米粒子空化的可控核增强高强度聚焦超声应用

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

小型化霍尔推进器的优化、测试和诊断

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...

Application of a Coupling Agent to Improve the Dielectric Properties of Polymer-Based Nanocomposites

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer matrix by adding 3-aminopropyltriethoxysilane (KH550) as a coupling agent during the fabrication process of BaTiO3-P(VDF-CTFE) nanocomposites through solution casting. Results show that the use of KH550 can modify the surface of ceramic nanofillers; therefore, good wettability on the ceramic-polymer interface was achieved, and the enhanced energy storage performances were obtained by a suitable amount of the coupling agent. This method can be used to prepare flexible composites, which is highly desirable for the production of high-performance film capacitors. If an excessive amount of coupling agent is used in the process, the non-attached coupling agent can participate in complex reactions, which leads to a decrease in dielectric constant and an increase in dielectric loss.

Here, we demonstrate a simple and low-cost solution-casting process to improve the compatibility between the filler and the matrix of polymer-based nanocomposites using surface modified BaTiO3 fillers, which can effectively enhance the energy density of the composites.

耦合剂在提高聚合物纳米复合物介电性能方面的应用

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer ...