學術演講8

introductory talk about research in Professor Kawamori's group

李宗懋 (成功大學電漿所 / 博士生)

<專題討論>2019/10/31(四)14:10綜合大樓2樓48218教室演講

Introduction to research by Professor Alfred Chen

陳炳志 副教授 (成功大學電漿所)

<專題討論>2019/10/3(四)14:10綜合大樓2樓48218教室演講

Exploring the Region where Earth Weather meets Space Weather: Ionospheric Connection Explorer (ICON)

Dr. Yen-Jung J. Wu (Space Sciences Laboratory, University of California, Berkeley))

<專題討論>2019/9/19(四)14:10綜合大樓2樓48218教室演講

摘要：

The NASA’s satellite mission Ionospheric Connection Explorer (ICON) is designed to target on the mesosphere and lower thermosphere (MLT) region where the earth weather meets space weather. The latest ICON launch date is scheduled in October 2019. In order to monitor the source and the response of the ionosphere dynamics, ICON has four instruments on board: 1) Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) provides the neutral wind velocity retrieving from 630.0 nm and 557.7 nm airglow, while the neutral temperature is extracted from 762.0 nm. 2) The Far Ultra Violet Imaging Spectrograph (FUV) measures 157.0 nm to retrieve the atmosphere O/N2 ratio and 135.6 nm recombination emission of O+ ions in the nighttime. 3) The Extreme Ultraviolet Spectrograph (EUV) measures 83.4 and 61.7 nm to retrieve O+ in the daytime. 4) The Ion Velocity Meter (IVM) provides the in-situ measurement of the meridional ion drift perpendicular to the magnetic field at the spacecraft altitude dear 575 km. IVM is used in conjunction with the other ICON instruments to understand the connection between the dynamics of neutral atmosphere and ionosphere through the generation of dynamo current. An overview of the ICON mission and the process from airglow intensity to the science data product will be focused in this talk.

| 附件: ISAPS20190919_Seminar.pdf

Characterization of a Single Microdischarge in Atmosperic-Pressure Air Dielectric Barrier Discharges

林昆模 助理教授 (中正大學機械工程學系)

<專題討論>2019/5/16(四)14:10綜合大樓2樓48218教室演講

摘要：

Atmospheric-pressure air dielectric barrier discharges (APADBDs) can be considered as one of the important plasma sources due to the developments in applications such as ozone generation, plasma-assisted combustion, active flow control, and pollution control. APADBDs are generated typically in either the coaxial or planar reactors featured as filamentary discharges with many current events observed during each voltage period as generally sustained by an AC power under few kHz frequency. These filaments, named microdischarges (MDs) in the literature, seem to occur randomly in both space and time. A single MD is the basic element producing reactive species (O, N, O3, etc.) and transferring charges across the gap between electrodes. Therefore, it is critical to understand the fundamental properties of a single MD for characterizing the APADBDs. An experimental platform was designed to investigate the statistical behavior of MDs generated in a planar APADBD reactor using a kHz sinusoidal power source. The features of a single MD are measured and compiled statistically. Moreover, numerical simulations provide another alternative to characterize a single MD generated in APADBDs. A semi-empirical 1.5D plasma fluid model is proposed to reveal the underneath chemical mechanisms taking place within the discharge column of a single MD.

| 附件: 20190516 林昆模助理教授.pdf

Investigation of the equatorial ionization anomaly structure

Prof. Alexander Trofimovich Karpachev (Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Moscow, Russia)

<專題討論>2019/4/23(二)13:10綜合大樓2樓48218教室演講

摘要：

The second lecture is devoted to the study and modeling of the structure of the equatorial ionosphere. The behavior of the equatorial ionosphere is completely determined by the extremely variable equatorial ionization anomaly (EIA). The characteristics of the EIA depend strongly on local time, longitude, altitude, geomagnetic and solar activity. The longitudinal and altitudinal variations can be investigated only by satellite data. Therefore, it is possible to explore entirety the EIA only by using the COSMIC data (Taiwan) for low solar activity and the Intercosmos-19 satellite (IZMIRAN) for high solar activity. This lecture is based on the results of the analysis of the EIA characteristics from the topside sounding onboard the Intercosmos-19. For the first time, a comprehensive pattern of variations in the EIA structure with local time, altitude, and longitude for all seasons was constructed and studied in detail. The EIA starts at 08 LT with the formation of a winter crest. The formation of EIA is associated with the action of solar ionization and the so-called fountain effect: electromagnetic drift directed upward takes the ionosphere plasma from the heights of the F2-layer maximum to great heights where it spreads along the magnetic field lines under the action of ambipolar diffusion, forming the crests of the anomaly. The summer crest appears only by 10 LT, it is located 3-4° farther from the equator than the winter one. During the equinox, the EIA at the development phase is also asymmetric: the southern crest appears first, but at noon the crests become symmetrical. During the day, EIA reaches its maximum development at 14 LT. The foF2 value over the equator and the degree of EIA development (EAI) at 12–14 LT vary with longitude according to changes in the velocity of the vertical plasma drift W. In the longitudinal variations of W, foF2 and EAI, the 4-th harmonic prevails at this time. In the evening 1.5–2.0 h after sunset (18-19 LT) burst in the vertical plasma drift velocity, the degree of EIA development rises to a maximum. The degree of EIA development after a maximum of 20-22 LT falls, but at midnight the anomaly is still rather well developed. After midnight, the foF2 maxima in the region of the crests of the anomaly, on the contrary, are farther from the equator, but this is apparently due to the action of the neutral wind. At 02 LT, in contrast to the morning hours, only the northern crest of the anomaly is clearly expressed. Thus, with high solar activity in any season, a well-pronounced EIA is observed from 12 to 24 LT. It reaches its maximum development by 20-22 LT. This is very different from the time of low solar activity, when EIA reaches the maximum at ~17 LT and completely decays by 20 LT.

The comparison of the EA structure for the high solar activity according to Intercosmos-19 and for low solar activity according to COSMIC will be discussed.

| 附件: 20190423 Prof. Karpachev.pdf