| 1. |
- Wan, Cheng-Liang, et al.
(författare)
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基于玻璃毛细管的大气环境MeV质子微束的产生与测量 : [Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary]
- 2024
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Ingår i: Wuli xuebao. - 1000-3290. ; 73:10
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Tidskriftsartikel (refereegranskat)abstract
- 本文采用玻璃毛细管产生了大气环境中工作的2.5 MeV质子外束微束, 并对束斑直径及能量分布随玻璃毛细管与束流方向之间角度(倾角)变化进行测量. 测量结果表明, 在玻璃毛细管轴向与束流方向一致时(倾角为0°), 产生的微束中存在保持初始入射能量的直接穿透部分以及散射部分, 其中直接穿透的质子占比最大, 束斑直径也最大. 随着玻璃毛细管倾角的增大, 当其大于几何张角时, 束斑直径变小, 产生的微束全部为能量减小的散射部分, 直接穿透质子消失. 我们对质子在玻璃毛细管内传输时的内壁散射过程进行了模拟计算及离子轨迹分析, 发现大角度的散射部分决定了形成的外束微束斑外围轮廓, 而束斑中心区域由不与毛细管内壁产生任何作用的直接穿透离子构成, 其大小由玻璃毛细管出口直径以及几何容许张角决定. 采用玻璃毛细管产生的外束微束具有产生简单廉价, 微束区域定位简单的特点, 有望在辐射生物学、医学、材料等领域得到广泛应用.
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| 2. |
- Wan, Cheng-Liang, et al.
(författare)
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Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary
- 2016
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Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 65:20
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Tidskriftsartikel (refereegranskat)abstract
- It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.
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| 3. |
- Li, Huixiong, et al.
(författare)
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蒸汽-冷流体接触冷凝流动的数值模拟
- 2005
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Ingår i: Gongcheng Rewuli Xuebao. - Beijing, China. - 0253-231X. ; 26, s. 963-966
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Tidskriftsartikel (refereegranskat)abstract
- 介绍了关于蒸汽-冷流体直接接触冷凝流动与传热的数值计算模型与部分研究结果。用Level Set方法确定蒸汽-冷流体接触界面的位置和形状,建立了对蒸汽和冷流体普遍适用的动量、能量和质量守恒方程,在能量和质量寺恒方程中增加了部分项用于计算蒸汽冷凝所产生的影响。用有限差分法在交错网格上离散控制方程,用Runge-Kutta法-五阶WENO组合格式求解Level Set输运方程,用压力修正的迭代Projection方法求解动量方程,而用SIMPLE方法求解温度控制方程。对算例的计算结果表明,本文所建立的数值计算模型能反映物理现象的宏观特性。根据计算结果,分析了本文模型的优缺点,并指出了今后改进的方向。
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| 4. |
- Li, Kai, et al.
(författare)
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Metal thermopile infrared detector with vertical graphene
- 2023
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Ingår i: Wuli Xuebao/Acta Physica Sinica. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 72:3
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Tidskriftsartikel (refereegranskat)abstract
- Thermopile infrared detector is a kind of detector device mainly composed of thermocouple as the basic unit. Because of its simple principle, no need of cooling equipment, and other advantages, it has been widely used in various fields of production and life. However, the absorption rates of the materials in conventional thermopile devices are poor, and the majority of them are incompatible with microfabrication methods. In this work, a metal thermopile infrared detector with vertical graphene (VG) is designed and fabricated. The VG is grown via plasma enhanced chemical vapor deposition, and retained at the device’s thermal ends to provide the thermopile IR detector’s wideband and high response characteristics. The detector achieves a room temperature responsivity reaching a value as high as 1.53 V/W at 792 nm, which can increase the response results about 28 times and reduce the response time to 0.8 ms compared with the thermopile detector without VG. After systematically measuring the response results, it is finally found that there are three main mechanisms responsible for the response on the composite device. The first one is the response generated by the metal thermopile itself alone. The second one is the response increased eventually by the contribution of VG covered at the metal thermal junction that expands the temperature difference. The last one is the response generated by the temperature gradient existing inside the VG on the surface of the device after the absorption of heat. The portion of each partial response mechanism in the total response is also analyzed, providing a new reference direction for analyzing the response generation mechanism of thermopile detectors with other absorbing materials. The process is compatible with the microfabrication, while the device performance is enhanced and suitable for mass production. Furthermore, by utilizing the surface plasmon resonance to combine VG with metal nanoparticles, the material’ s light absorption is found to be enhanced significantly under the same conditions, and the resulting thermal voltage can be increased to 6 times. The results indicate that VG promises to possess practical applications, in many fields such as photoelectric sensing and power production devices. This technology provides a new method to manufacture high-performance thermopile infrared detectors and other sensor devices.
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| 5. |
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| 6. |
- Li, Liangxing, et al.
(författare)
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冷中子源冷包截面含汽率数理模型探讨
- 2005
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Ingår i: Proceedings of the 11<sup>th</sup> Annual Meeting of Chinese Engineering Thermophysics.
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Konferensbidrag (refereegranskat)
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| 7. |
- Li, Liangxing, et al.
(författare)
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冷中子源冷包截面含汽率数理模型探讨
- 2007
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Ingår i: Gongcheng Rewuli Xuebao. - Beijing, China. - 0253-231X. ; 28, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- 文章推导出一种计算冷包截面含汽率的数学模型;将模型计算结果与已知文献相关实验结果进行对比,验证了模型的正确性.利用该模型探讨了冷包截面含汽率的影响因素如气泡直径,工质液体的密度、粘性,加热功率等.模型计算表明:气泡直径越大,在同一截面高度处的截面含汽率越低;工质粘性越大,在同一截面高度处的截面含汽率越高.本文模型的计算结果能对冷包设计提供理论支持.
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| 8. |
- Li, Liangxing, et al.
(författare)
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熔融液滴与冷却剂相互作用实验中液滴释放控制机构的研制
- 2008
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Ingår i: Hedongli Gongcheng. - ChengDu, China. - 0258-0926. ; 29, s. 42-45
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Tidskriftsartikel (refereegranskat)abstract
- 在高温熔融液滴与冷却剂相互作用的实验中,熔融液滴的释放控制对整个实验起至关重要的作用。本文在以往实验机械控制装置的基础上,自主设计一个自动控制电路来代替人工机械操作,利用控制电路给电磁铁提供瞬时脉冲来控制液滴瞬时释放下落,简化实验的可持续性操作,提高实验的重复性、精确性和操作方便性。
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| 9. |
- Li, Liangxing, et al.
(författare)
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熔融液滴在冷却剂中的运动特性实验
- 2007
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Ingår i: Hedongli Gongcheng. - Chengdu, China. - 0258-0926. ; 28, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- 设计、建立了研究高温熔融液滴与冷却剂相互作用的可视化实验装置,通过高速摄影记录熔融液滴的下落过程,获得了下落小球运动过程曲线,重点考察了液滴温度和冷却剂温度对液滴-冷却剂界面作用过程的影响。结果表明,熔融液滴穿过气-水界面后,将首先经历一个速度骤降-回升过程,之后液滴作减速运动下落;当冷却水温度一定时,高温熔融液滴温度越高,熔融液滴入水后下落速度越快;当熔融液滴温度一定时,冷却水温度越高,熔融液滴入水后下落速度越快。
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| 10. |
- Qian, Li-Bing, et al.
(författare)
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Transmission of electrons through the conical glass capillary with the grounded conducting outer surface
- 2017
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Ingår i: Wuli xuebao. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 66:12
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Tidskriftsartikel (refereegranskat)abstract
- The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i. e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial.. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the two-dimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm x 0.5 mm and a divergence of less than 0.35.. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 mu m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys: Si n: 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i. e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.
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