A Brief Introduction of Pulsed Power Technology History, Basics, and Applications
鍾慎修 博士 ( 空軍航校通電系兼任助理教授 )
<專題討論>2017/5/18(四)14:30綜合大樓2樓48218教室演講
Pulsed Power (PP) technology deals with storing energy over a relatively long period of time (sec-min), and releases it within a very short time (ns-us) to achieve very high electrical output power to the load. The birth of PP technology is deeply related to the development of nuclear weapon, from the ignition of fission bomb to the simulation of prompt intense X-rays burst and radiation transport in Ulam-Teller design. The Partial Nuclear Test Ban Treaty signed in 1963 accelerated the development of PP, and since then it has evolved into many military and commercial applications, but the main focus is on fusion research. Because the original design of boosted fission weapon and hydrogen bomb have strong influence over the fusion research decades to come, therefore we will begin by a simple explanation of the nuclear weapon design. Next we will briefly review the history of PP in US and UK, and explain the key milestones and concept changes; this will be followed by the introduction of the basics in PP technology like the common PP configurations, the energy storage configuration, capacitor, inductor, spark gap, Marx Banks, Blumlein line, superconductive magnetic energy storage (SMES), and linear transformer driver (LTD). Application examples include EMP simulator, X-ray radiograph, High Power Microwave (HPM), railgun, and fusion research like the Z-machine. Finally we will introduce foreign proposals for future big PP facilities.
| 附件: 20170518 鍾慎修博士.pdf
Virtual potential in the feedback trap and Landauer's principle
田溶根 副教授 ( 中央大學物理系)
<專題討論>2017/5/11(四)14:30綜合大樓2樓48218教室演講
In this talk, I will introduce the feedback trap using the electrophoretic force, called Anti-Brownian ELectrophoretic (ABEL) trap. This is a tool for trapping and manipulating a less-than-micron-sized charged object. The trap first acquires the position of a molecule, calculates the corresponding force of the desired potential, and applies the feedback voltage to bring the molecule to the destination, and finally, can generate the arbitrary VIRTUAL potential whose dynamics is very close to the real potential.
As an application of the virtual potential in the feedback trap, I will also present the experimental study on the fundamental connections between information and thermodynamics, especially, the Landauer's principle. It states that an irreversible logical operation must dissipate energy into heat, no matter how slowly it is performed. For example, RESET of one-bit memory requires at least kTln2 of work, which is called Landauer's erasure principle. We manipulated a colloidal particle starting from the left or right well and ending up the right well, indicating the reduction of two possible states to one. In this process, we found that the work required gradually approaches to kTln2 as the processing cycle time increases.
| 附件: 20170511 田溶根副教授.pdf
Effects of polarization-charge shielding in microwave heating
朱國瑞 院士 ( 臺灣大學物理系)
<專題討論>2017/5/4(四)14:30綜合大樓2樓48218教室演講
Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating is often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample’s shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly-polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.”
| 附件: 20170504 朱國瑞院士演講海報.pdf
Using Aerosol-Assisted Atmospheric Pressure Plasma to Rapidly Immobilize Protein onto Substrate for Biosensor Fabrication
鄭雲謙 助理教授 ( 交通大學機械工程系 )
<專題討論>2017/4/27(四)14:10綜合大樓2樓48218教室演講
Atmospheric pressure plasma deposition (APPD) polymerization has more possible applications than low-pressure plasma polymerization due to its low cost and utilization versatility. One of the applications is protein immobilization, which can be used for biosensor fabrication. The conventional immobilization process of protein is complicated and regent consuming. On the contrary, the aerosol-assisted dielectric barrier discharge APPD (DBD-APPD) technique can deposit polyethylene (PE) film with OH functional groups and embed protein at the same time, making the immobilization process faster and avoids use of harmful reagents[1-3]. Hence, this work used DBD-APPD to immobilized protein onto substrate for biosensing application. As a result, we immobilized BSA with DBD-APPD, and the staining result shows that the biosening application is feasible.
| 附件: 20170427 鄭雲謙助理教授.pdf
The nonlinear optics of coherent EUV generation: harness attosecond science and nano imaging
陳明彰 助理教授 ( 清華大學光電工程研究所 )
<專題討論>2017/4/20(四)14:10綜合大樓2樓48218教室演講
To explore the world, people use their eyes and hands to see and to manipulate the objects around them. To see the nano-world and ultrafast electron dynamics, the development of new tools is highly desired in this generation. When moving my research career back to NTHU in 2013 spring, I built a EUV&ATTO lab aiming for making a bright, coherent table-top EUV and soft X-ray lasers. My recent research is focusing on understanding the mechanism of high order harmonic generation (HHG) — a process to convert visible/infrared light into light with much shorter wavelength. Simply speaking, when intense visible/infrared light is focused into noble gas atoms, the nonlinear interaction between them could give light with tens of times higher frequency. The spectrum, spatial coherence and brightness of the generated light depend on a lot of parameters like the interaction geometry, the driving laser frequency, and how well the phase matching condition is satisfied. Huge progresses have been made in recent years during my research in NTHU. This new accessible and reliable table-top EUV light source makes a lot of the first possibilities in Taiwan, e.g. providing ultrafast EUV light for Time-Resolved Angle-resolved Photoemission Spectroscopy (TR-ARPES) in NSRRC, and coherent 13.5nm EUV light source for semiconductor industries for nanometer-scale defect inspection.
| 附件: 20170420 陳明彰助理教授.pdf
Recent Advances in Organic/Inorganic Hybrid Solar Cells
孫建文 教授 ( 交通大學應用化學系 )
專題討論>2017/4/13(四)14:10綜合大樓2樓48218教室演講
A number of techniques for photon to electricity conversion have been attempted over the decades and the use of semiconducting materials has been the most successful. Although semiconductor PVs dominate the current photovoltaic market share, the high temperature and costly fabrication processes have kept the cost of energy produced high, preventing the mass uptake of the technology. Organic solar cells that are created with conjugated polymers, which can be fabricated with inexpensive materials by using low temperature solution processes, and have the potential to lower costs; however, the efficiency of organic solar cells is lower than semiconductor-based devices. Therefore, hybrid solar cells that combine inorganic semiconductors (Si, GaAs) and conjugated polymers at low temperatures provide a possible alternative technology to simplify fabrication processes and reduce costs. This talk mainly examines key issues of hybrid photovoltaic systems. These are PEDOT:PSS/single crystalline Si and PEDOT:PSS/GaAs systems, which are showing growing importance and potential in the literature. Recent advances in terms of device performance for these respective topics are discussed, along with an outlook for each hybrid system.
| 附件: 20170413 孫建文教授.pdf
Progress towards predictive modelling of turbulence and transport in the edge plasma of magnetic confinement devices」
Prof. Ben Dudson ( Department of Physics, University of York, UK )
<演講公告>2017/4/13(四)11:00綜合大樓2樓48218教室演講
Understanding the transport processes in the low temperature plasma at the boundary region of magnetic confinement fusion (MCF) devices is of critical importance to the design and operation of next step fusion reactor devices. It influences the divertor heat load, and probably the core confinement as well. While present models of the divertor and Scrape-off Layer (SOL) are successful for interpretative plasma transport, further model development is needed for a truly predictive model. To address that need we have extended the BOUT++ computational platform to study and predict turbulence and transport in the divertor, building on our previous studies of the pedestal and SOL regions upstream from the divertor. We have incorporated (a) improved treatments of the x-point, necessaryfor advanced divertor geometries; (b) neutral gas & impurity models, to reproduce the transport physics embodied in current 2D SOL/divertor transport codes. We have explored both fluid and kinetic models for neutrals, and found that turbulence modifies the local neutral gas density – key physics in the detachment process. Conversely, neutral gas is found to affect plasma edge turbulence primarily through momentum exchange, reducing the radial electric field and enhancing cross-field transport, with consequent implications for the SOL width and divertor heat loads. New schemes for treating complex magnetic field geometries in BOUT++, based on the Flux Coordinate Independent (FCI) method, show promise for extending our studies to 3D stellarator geometries. Progress in integrating all the elements being developed into a fully 3D predictive simulation will be discussed.
清代上海地區氣候與天氣特徵之重建
談珮華 教授 (嘉義大學應用歷史學系 )
<專題討論>2017/4/6(四)14:10綜合大樓2樓48218教室演講
本研究分析中國歷史文獻中關於天氣現象之描述，重建清代 (西元1644- 1911年) 上海地區的氣候狀況，包括乾濕序列與溫度序列之時間分布、颱風、冰雹、雷暴、龍捲風與潮溢等特殊天氣現象之時空分布，以及氣象因子的相關。
平均及極端乾濕二種逐年序列皆顯示，在1644-1730年代乾濕交替較為劇烈，而從1740年代以後，則是偏濕型態。冬溫及夏溫的十年期序列皆呈現清代前後各有一個約五十年的冷期，中間為一百五十年的相對暖期。清代268年期間沒有明顯的增溫趨勢。夏季溫度與極端降水的十年期資料有顯著負相關，表示極端降水較多時，夏溫較低，溫濕呈現是不同步的變化。
颱風、冰雹、雷暴、龍捲風及潮溢發生次數，平均10年有2.5、2.3、3.6、1.8及3.6次，雷暴及潮溢並列第一。五十年累積次數顯示，颱風侵襲上海次數以清代中期較多，清初及清末較少；相反地，冰雹、雷暴及龍捲風發生次數以清初及清末較多，清代中期明顯偏少；潮溢次數以清初的50年最多，爾後兩百年逐漸減少。在空間分布方面，颱風發生次數以東南及西北部最多，冰雹、雷暴及龍捲風分布型態類似，發生次數以中部西北部較多，這些可能與位於沿河海區及區域開發程度較高有關；潮溢發生次數則以沿河海區及離島縣市最多，表示深受河川水位及海潮的影響。
溫濕及特殊天氣發生次數的相關分析顯示，颱風對全年的平均及極端降水皆有貢獻，全年及冬季的雷暴較多時，全年及冬季的平均降水會較多，而夏溫會較低及潮溢發生次數會較多。特殊天氣現象的時空相關顯示，若有颱風及龍捲風侵襲，易發生潮溢現象。冰雹、雷暴及龍捲風也常相伴發生，可能是這些特殊天氣皆與強烈對流系統與大尺度不穩定大氣有關。
| 附件: 20170406 談珮華教授.pdf
Introduction to tokamak experiments
Dr. Hyungho Lee ( KSTAR Research Center, National Fusion Research Institute, Korea )
<專題討論>2017/3/23(四)14:10綜合大樓2樓48218教室演講
This talk provides a brief overview of tokamak experiments. The tokamak is widely recognized as the most promising candidate for realizing a nuclear fusion power plant. However, there still remain many issues to be resolved in order to harness the fusion energy in a tokamak. The critical parameters for realizing fusion energy reactor can be found in the fusion triple product ni Ti tE, which results from a power balance consideration. Here, ni , Ti and tE are the ion density, the ion temperature, and plasma energy confinement time, respectively. Thus, the tokamak research has been dominated by the search for improved confinement regime (tE ) with high plasma pressure (ni and Ti ). In this talk, the history of research into improved confinement regimes such as H-mode and ITB discharges are briefly introduced followed by a short overview of theoretical and numerical models which have been suggested to understand the confinement regimes. On the one hand, it has been observed that improved confinement regimes occasionally accompany several macroscopic magneto- hydrodynamics (MHD) modes such as tearing modes and edge localized modes. To avoid their harmful effects on the plasma operation, we have to suppress or mitigate them in a reactor-sized tokamak plasma. Here, the experimental efforts in suppressing these MHD modes are briefly discussed. In a reactor-sized tokamak, the high heat flux from high pressure plasma onto the plasma facing components is also one of critical issues. Thus, searching for the effective power exhausting methods has become one of main research goals in fusion community. Several experimental achievements in this research field are also included in this talk.
Impurity particle transport in the tokamak plasmas
Dr. JaeChun Seol ( KSTAR Research Center, National Fusion Research Institute, Korea)
<演講公告>2017/3/21(二)11:00綜合大樓2樓48218教室演講
The light nuclei such as deuterium and tritium can fuse to produce other nuclei such as alpha particle and neutron. In this process, kinetic energies come out with alpha particle and neutron. However, the nuclear fusion power deceases when the plasma is diluted by unwanted impurity particles. Moreover, the heavy impurity particles can be more harmful since they cause the radiation power loss, which decreases the plasma temperature. In this presentation, the basics of impurity particle transport is discussed. Recent experimental results are also introduced.