學術演講9

To explore nano world and material science by X-ray nano probe at Taiwan photon source

曾紹欽 博士(財團法人國家同步輻射研究中心)

<專題討論>2020/5/7(四)14:10綜合大樓2樓48218教室演講

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.

| 附件: 20200507 曾紹欽博士.pdf

The Prime Focus Spectrograph for the Subaru Telescope

王祥宇 博士(中央研究院天文所)

<專題討論>2020/4/23(四)14:10綜合大樓2樓48218教室演講

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.

| 附件: 20200423 王祥宇博士.pdf

Laser and Optical Diagnostics Systems for Plasmas: Industrial Plasmas and Laboratory Space Science

Dr. Nima Bolouki(明志科技大學電漿與薄膜科技中心)

<專題討論>2020/3/26(四)14:10綜合大樓2樓48218教室演講

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

| 附件: 20200326 Dr. Nima Bolouki.pdf

MAGNETOHYDRODYNAMIC MODELING OF THERMAL PLASMA FLOW AND ITS APPLICATION TO DIRECT-CURRENT PLASMA TORCH

趙修武 教授 (臺灣大學工程科學及海洋工程學系)

<專題討論>2020/3/12(四)14:10綜合大樓2樓48218教室演講

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.

| 附件: 20200312 趙修武教授.pdf

Numerical study of plasma-object interaction: Debye-scale Langmuir probe

Dr. Chun-Sung Jao(Institute of Space Science and Engineering, National Central University)

(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

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.

| 附件: 20191205 饒駿頌博士.pdf