學術演講


<專題討論>2020/5/7(四)14:10綜合大樓2樓48218教室演講 : 曾紹欽 博士(財團法人國家同步輻射研究中心)

張貼者:2020年5月3日 下午7:53Dabby Lu

講題: To explore nano world and material science by X-ray nano probe at Taiwan photon source
摘要: Introduction to fundamental and technic aspects of the particularity of Taiwan Photon Source and apply X-ray nanoprobe to scientific research. In this talk, that will show some experimental cases like the X-ray fluorescence spectroscopy (for the analysis in the depth-of-field distribution of elements), extended X-ray absorption spectroscopy (for the analysis in the electronic configuration and the atomic or molecular bonding length), excitation X-ray fluorescence spectroscopy (for the analysis in the recombination and transport of carriers), in-phase scanning X-ray imageology (the Fourier phase transform calculation can improve the space resolution down to 3nm to 5nm, and detect the stress distribution inside the nanostructures). Moreover, the in-situ electrical testing system with 13 channels has been developed as well. It can be used to the in-situ measurement on the properties of semiconductor and optoelectronic devices when they are under operation.

<專題討論>2020/4/30(四)14:10綜合大樓2樓48218教室演講 : 柳克強 教授(清華大學工程與系統科學系)

張貼者:2020年4月26日 下午8:28Dabby Lu

講題: Low temperature plasmas – Characterizations and Applications
摘要: Low temperature plasmas have a wide range of applications, including micro/nano fabrication, lighting/displays, and even bio-medical treatments.  In this talk, an overview of fundamentals of low temperature plasmas will first be given.  In the second part of this talk, results from our recent efforts on fluid model simulations analysis and microwave based diagnostics will be highlighted.  The numerical simulations were conducted by using a commercial code – COMSOL Multi-physics.  The first reactor studied is a microwave plasma discharge operated at the TM023 cavity mode.  Simulation results show that a hot plasma ball located above the grounded stage can be sustained by microwave power propagating along the stage surface in a surface wave type mode.  Simulation analysis has also been conducted for ferromagnetic enhanced inductively coupled plasmas (FMICP).  As a results of a structure consisting of a metallic enclosure and a DC-block, simulation results reveal a discharge mode transition from capacitive to inductive coupling, an important physical mechanism for the ignition and sustaining of the FMICP discharges.  For the microwave based diagnostics, two types of sensors have been investigated.  The first one is based on a transmission line and is operated as an interferometer.  The density is determined by the phase shift of a microwave going through the transmission line as the plasma density is varied.  Several transmission line structures have been studied, including a coaxial line, a ridged microstrip line and an air-bridge microstrip line.  Numerical Simulation analysis and experimental results show that the air-bridge structure yields the highest sensitive for plasma density measurements.  The second type of device is a probe employing a microwave resonant structure where the resonant frequency is also affected by the plasma density.   Characteristics of several resonant type microwave plasma density sensors being developed will also be presented.  

<專題討論>2020/4/23(四)14:10綜合大樓2樓48218教室演講 : 王祥宇 博士(中央研究院天文所)

張貼者:2020年4月16日 下午8:27Dabby Lu

講題: The Prime Focus Spectrograph for the Subaru Telescope
摘要: The Prime Focus Spectrograph (PFS) is a fiber fed spectrograph system with a fiber positioner system designed to be mounted at the prime focus of the Subaru 8.2m telescope on Mauna Kea, and feeding 4 fixed spectrographs mounted near the Nasmyth focus. With 2394 fibers & fiber positioners, PFS allows simultaneous spectral observations of up to 2394 astronomical targets. Fibers then carry light to spectrographs covering the wavelength ranges from 0.38 um to 1.3 um with an average resolving power of 3000. Before and during the era of extremely large telescopes, PFS will provide the unique capability of obtaining spectra of 2400 cosmological/astrophysical targets simultaneously with an 8-10 meter class telescope. This optical/near-infrared multi-fiber spectrograph targets cosmology with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution. 
The PFS collaboration, led by IPMU, consists of ASIAA in Taiwan, USP/LNA in Brazil, Chinese Consortium, Caltech/JPL, Princeton & JHU and NorthEast Participation Group in USA, LAM in France, Max Planck Society in Germany, NAOJ/Subaru, IPMU in Japan. The project started in late 2010 and is now in the last development phase. In this talk, the details of the PFS design and development status will be presented. The planning of the coming Subaru Strategic Survey will also be briefed.

<專題討論>2020/4/16(四)14:10綜合大樓2樓48218教室演講 : 張博宇 助理教授(成功大學電漿所)

張貼者:2020年4月13日 上午1:53Dabby Lu

講題: Tips on Presentation
摘要: Presentation is an important skill to let other people know what your work is in a short period of time. The quality of the presentation depends on how the slides are made and the way the presentation is given. Several tips the speaker learned from the Laboratory for Laser Energetics at University of Rochester will be given.

<專題討論>2020/3/26(四)14:10綜合大樓2樓48218教室演講 : Dr. Nima Bolouki(明志科技大學電漿與薄膜科技中心)

張貼者:2020年3月19日 下午11:26Dabby Lu

講題: Laser and Optical Diagnostics Systems for Plasmas: Industrial Plasmas and Laboratory Space Science
摘要: Plasma diagnostics tools play an essential role in measurements of plasma parameters. The diagnostics tools are widely employed in various plasmas to measure electron density, electron energy distribution function, particle density, electric field, and so on. Moreover, diagnosing plasmas allows us to follow practical observations of physical processes inside the plasmas. This seminar will introduce the basic concepts of spectroscopic methods as one of the most powerful diagnostics tools. The experimental techniques associated with optical emission spectroscopy and laser-aided diagnostics will be presented. Finally, the results of laser Thomson scattering measurements will be explained in two different areas of plasmas in terms of temperature and density: low-temperature industrial plasmas and high energy plasmas which appear as laser-produced plasmas in laboratory space science.

<專題討論>2020/3/19(四)14:10綜合大樓2樓48218教室演講 : 林哲信 教授(中山大學機械與機電工程學系)

張貼者:2020年3月16日 上午2:26Dabby Lu

講題: 常壓電漿整合質譜於生醫與農藥之應用

<專題討論>2020/3/12(四)14:10綜合大樓2樓48218教室演講 : 趙修武 教授 (臺灣大學工程科學及海洋工程學系)

張貼者:2020年3月5日 下午10:46Dabby Lu

講題: MAGNETOHYDRODYNAMIC MODELING OF THERMAL PLASMA FLOW AND ITS APPLICATION TO DIRECT-CURRENT PLASMA TORCH
摘要: Direct-current plasma torch is a widely adopted thermal plasma device applied to various industrial applications, where high-temperature plasma jets are produced due to the substantial interaction between neutral working gases and arc columns. The applied electric arc principally works as the main energy provider to accelerate the plasma flow along with elevating its temperature to obtain the required processing capabilities. A steady magnetohydrodynamic model is proposed to describe the thermal plasma flow of a direct-current plasma torch where the continuity, momentum and energy equations incorporated with a turbulence model are considered to depict the dependence among the flow velocity, working pressure and gas temperature of the plasma jet subjected to an applied electric accompanied by a self-induced magnetic field. The azimuthal velocity component is also considered in the proposed model for capturing the significant rotational motion of plasma flow as a consequence of tangential inflow design. The thermal plasma is assumed electrically neutral, optically thin and in local thermal equilibrium. The time-averaged solution is employed because of a focus on engineering operation. For reactive thermal plasmas, the transport equations of charged particles described by a drift-diffusion approximation as well as the transport equations of the neutral species are modeled following the chemical and plasma kinetics among different plasma components. The energy balance equation of electron is furthermore introduced when the non-thermal equilibrium plasma is considered. The governing equations are segregated solved on a Cartesian grid via a finite volume discretization, where a linear parallelization is achieved through the MPI library. The proposed numerical scheme is implemented in an in-house code PTCAX. Several applications of the direct-current plasma torch are discussed to disclose the complex physics of thermal plasma flow interacting with a direct-current arc.

Keywords: Magnetohydrodynamic Modeling, Thermal Plasma, Direct-Current, Plasma Torch.

2019/11/29(五)13:00綜合大樓1樓48111B教室演講 : 張滋芳 博士(成功大學前瞻電漿研究中心)

張貼者:2019年11月27日 下午11:49Dabby Lu

講題: ERG Project and Development of SPEDAS
摘要: The ERG (Exploration of energization and Radiation in Geospace) project explores the acceleration, transport, and loss of relativistic electrons in the radiation belts. Radiation belts are regions of enhanced populations of energetic electrons and protons surrounding the Earth in the magnetosphere. For the first time, Taiwanese participate in a magnetospheric exploration mission - JAXA‐led ERG mission. Through years of efforts, Taiwan team has successfully delivered the LEP‐e (Lowenergy particle experiments–electron analyzer) for deployment on the ERG satellite. The ERG satellite has been successfully launched on December 20, 2016 from the Uchinoura Space Center. Besides the ERG satellite, spacecraft missions conducted by several countries have begun to work synergistically to explore the science associated with space weather. In addition, ground‐based network observatories also work closely together for revealing the complex dynamics of the Earth’s magnetosphere, which is strongly associated with the variability of space weather. To integrate the data from all the space‐borne and ground‐based assets can be daunting. The ERG project adopts the SPEDAS (Space Physics Environment Data Analysis System) as the project data analysis software. The development of SPEDAS is a key to efficiently study the space physics data in the golden era of space research.

(原11/28延期為12/5)2019/12/5(四)13:00綜合大樓1樓48111B教室演講 : Dr. Chun-Sung Jao(Institute of Space Science and Engineering, National Central University)

張貼者:2019年11月25日 下午6:48Dabby Lu   [ 已更新 2019年12月2日 下午5:38 ]

講題: Numerical study of plasma-object interaction: Debye-scale Langmuir probe
摘要: The instrument-carrying satellite and sounding rocket missions are designed to take measurements along the trajectory of spacecraft. However, it is well-known that the local plasma will be disturbed in the process of plasma-object interactions, such as spacecraft body and booms, resulting in the influence on the plasma measurements. For the high-resolution plasma density data, the multi-needle Langmuir probe (m-NLP) instrument, which consists of two or more Langmuir probes, is widely used in the in-situ measurement missions. However, we found that the interaction between space plasma and single Debye-scale probe may also affect the measurement of other probes. To clarify this issue, we employ a self-consistent unstructured Particle-In-Cell model for numerical studies. These studies can provide a reference for the data processing and the future design of m-NLP instruments.

2019/11/25(一)13:00綜合大樓1樓48111B教室演講 : 陳乃華 博士(國家高速網路與計算中心)

張貼者:2019年11月21日 下午9:04Dabby Lu   [ 已更新 2019年11月25日 下午6:49 ]

講題: How is AI changing our work in space science?
摘要: Machine learning has merged as a useful method in various applications. Recent years numerous breakthroughs have spiked the use of machine learning and also initiate the experimental researches in the scientific community. In combination of computing facility and massive dataset, machine learning has made a great progress in tasks like image classification. Such technology indeed causes a lot of attentions and concerns.  How can we benefit from such technology in the near future?  In this talk, I will briefly introduce the current usage of machine learning in space science, such as solar flare occurrence, solar spectral irradiance etc.

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