Patterns of Plasma Bullet in Plasma Jets

Gook Hee Han,Je Huan Koo,Duk In Choi,Eun Ha Choi,Guangsup Cho Institute of Electrical and Electronics Engineers 2015 IEEE transactions on plasma science Vol. No.

<P>Composite charges applied to plasma striations were investigated through this paper. Bullets in plasma jets stemming from effective electrons made up of a moving target electron with screening electrons and ions around it were assessed using an atom-like structure induced by an external electric or magnetic field. To maintain a zero total charge, screening electrons and ions were assumed to be spherically and symmetrically distributed around a target moving electron -e, and the surrounding -e or +e was equivalent to the composition of an electric field vortex and an electron. Electrons moving around a spherical orbit were found to have positive charges under a strong electric field but negative charges under a weak field, mainly because the cross-sectional area of the flux was very small. In plasma jets, striations are a phenomenon that may occur when charges gather in the presence of an electric or gauge field. A plasma striation can occur if the effective charge exceeds a critical value determined by setting the derivative of the effective charge to zero, but only if the electric field lines passing through the striation are connected.</P>

Comprehensive Electric-Thermal Photovoltaic Modeling for Power-Hardware-in-the-Loop Simulation (PHILS) Applications

Xuan Hung Mai,Sang-Kyu Kwak,Jee-Hoon Jung,Kim, Katherine A. Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol.64 No.8

<P>This paper presents a dynamic, electricthermal model for a photovoltaic (PV) cell that combines electrical and thermal parameters to accurately emulate PV panels in real time for power-hardware-in-the-loop simulation (PHILS). In this model, the irradiance and ambient temperature are used to calculate the PV cell temperature based on a five-layer thermal model. The cell temperature is then used in the electrical model to accurately adjust the PV electrical characteristics. A custom experimental setup is built to test and verify the electrical and thermal characteristics of the PV cell model. This electric-thermal model is validated using experimental data in realistic scenarios. The model is also tested with PHILS using a real-time simulator and a programmable dc power supply to emulate PV power generation under various load changes. The model is well matched to the experimental measurements with an error within 2.4% for the electrical aspects and within 1.5% for the thermal aspects in the tested scenarios.</P>

Design of a 6-MW Solid-State Pulse Modulator Using Marx Generator for the Medical Linac

Lim, Heuijin,Jeong, Dong Hyeok,Lee, Manwoo,Ro, Sung Chae Institute of Electrical and Electronics Engineers 2017 IEEE transactions on plasma science Vol. No.

<P>The linear accelerators (linacs) producing high energy and high power of electron-beam or X-ray beam have been used in medicine, industry, national security, etc. In the linac, the electrons are generated by the electron gun and accelerated in the accelerating column with the high-power RF fields. The high-voltage pulses from the pulse modulator are supplied to the RF power source and the electron gun. The pulse modulator is one of the big and expensive components in the linac. The commercial medical linacs commonly use the pulse modulator based on the thyratron-switched pulse-forming network. In order to improve the power efficiency, achieve the system compactness, and optimize the cost and space, the solid-state pulse modulator based on the Marx generator was proposed. The low-power solid-state pulse modulator was developed for the electron gun operation. The conceptual design and functional results were confirmed. In order to apply it to the RF power source, such as a magnetron or a klystron, the 6-MW pulse modulator with the same Marx scheme is proposed. It consists of 40 storage-switch stages and one high-voltage pulse transformer, producing the pulse of 50 kV and 120 A required by the magnetron in the medical linac. A storage-switch stage was designed for insulated gate bipolar transistors to switch high current of 280 A and 720 V and to use the capacitor of 25 mu F which was chosen for the voltage droop of 10% with the pulsewidth of 5 mu s. The prototype system with eight storage-switch stages was fabricated and tested with a load system. The performance results show that it can be extended to be the 6-MW solid-state pulse modulator. In this paper, we describe the design features, and discuss the results and also the future plan to optimize the solid-state pulse modulator in the medical linac.</P>

Raman Scattering Studies of <tex> ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-{\rm x}}$</tex> Films Grown by High-Rate e-Beam Co-Evaporation

Lee, E.,Yoon, H.R.,Jo, W.,Yoon, S.,Cheong, H.,Lee, H.G.,Hong, G.W.,Huh, J.U.,Hammond, R.H.,Beasley, M.R. Institute of Electrical and Electronics Engineers 2007 IEEE transactions on applied superconductivity Vol.17 No.2

<P>We present results of Raman scattering studies of superconducting YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-x</SUB> (YBCO) films grown by a high-rate electron-beam co-evaporation method. It is shown by X-ray diffraction that the as-grown YBCO films have a highly c-axis oriented and in-plane aligned texture. Raman scattering measurements were used to study optical phonon modes, oxygen content and second phases of the YBCO coated conductors. Raman spectra of YBCO films with lower-transport properties exhibit additional phonon modes at ~ 300 cm<SUP>-1</SUP>, ~ 600 cm<SUP>-1</SUP>, and ~ 630 cm<SUP>-1</SUP>, which are related to second-phases such as Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>5.9</SUB> and BaCuO<SUB>2</SUB>. We also performed micro-Raman scattering measurements, which enable the local characterization of the material over a few micrometer scales. We could clearly determine the chemical homogeneities of the films on which we could not have information using XRD. Our results strongly suggest that micro-Raman scattering can be a very effective tool for characterizing structural and chemical properties, which is essential for optimizing growth conditions.</P>

Schottky Barrier in Organic Transistors

Xu, Yong,Sun, Huabin,Noh, Yong-Young Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electron devices Vol.64 No.5

<P>Organic FETs (OFETs) are essential devices in future flexible electronics. Yet, a crucial issue associated with electronic contact is still unsolved and our fundamental understanding remains very limited. Unlike many other previous reports talking about the contact resistance, in this paper, we specifically discuss its major root: the Schottky barrier, by comparison of the conventional metal-silicon contacts, and the unconventional metal-organic contacts, where the special features in OFETs are underlined. We not only examine the basics of the Schottky barrier but also the extrinsic effects as well as the characterization methods. The key factors in device fabrication are also reviewed in order to minimize the detrimental impacts of the Schottky barrier for obtaining optimum device performance.</P>

Electric-Circuit-Embedded Polymer Optical Bench

Kim, Jin Tae,Ju, Jung Jin,Park, Suntak,Park, Seung Koo,Kim, Min-Su,Lee, Myung-Hyun Institute of Electrical and Electronics Engineers 2007 IEEE photonics technology letters Vol.19 No.5-8

<P>In order to overcome the shortcomings of silicon optical bench with surface-patterned electric circuits, an electric-circuit-embedded polymer optical bench was developed. The main design issue was to embed the electric circuit under the optical bench and to let the electric contact pads be opened at the bottom of the alignment pits. To accommodate the surplus conductive adhesive, adhesive-fill space was created at the alignment pits. This architectural invention provides not only more efficient fiber-chip coupling of the planar-lightwave-circuit-type optical waveguide device but also a good electrical contact. An upside-down mounted single-mode waveguide chip showed a coupling loss of about 0.9 dB per coupling face with a single-mode fiber at a wavelength of 1.5 mum</P>

Impact of Equivalent Oxide Thickness on Threshold Voltage Variation Induced by Work-Function Variation in Multigate Devices

Lee, Youngtaek,Shin, Changhwan Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electron devices Vol. No.

<P>Using 3-D technology computer aided design simulation, we investigated the impact of equivalent oxide thickness (EOT) on threshold voltage (V-TH) variation induced by work-function variation (WFV) in multigate devices. The WFV-induced VTH variation in multigate devices does not significantly vary with the dielectric constant of the gate dielectric material, but increases with decreasingphysicaloxide thickness(T-OX). As T-OX becomes thinner, electric field tends to be locally concentrated, causing a large variation of electrostatic potential in channel. The slope of the ratio of average grain size to gate area (RGG) plot is observed with various oxide thicknesses. It is confirmed that we can alleviate the WFV-induced VTH variation without significant performance degradation if gate dielectric layer becomes thicker with appropriately adopted higher-k engineering. In addition, the impact of EOT (including interface layer) on the WFV-induced VTH variation is studied.</P>

RCEPD With Enhanced Light Absorption by Crown-Shaped Quantum Well

Gun Wu Ju,Byung Hoon Na,Hee Ju Choi,Kwang Wook Park,Young Min Song,Yong Tak Lee Institute of Electrical and Electronics Engineers 2015 IEEE photonics technology letters Vol.27 No.19

<P>A high-performance resonant cavity enhanced photodetector (RCEPD) is developed by introducing an InGaAs/GaAs crown-shaped quantum well (CSQW) structure. In calculation, the absorption coefficient of the proposed CSQW structure is significantly enhanced by 47.8% compared with that of the conventional QW without increasing the electric field due to the large overlap of electron/hole-wave functions. To verify the feasibility of our proposed QW structure, we fabricate RCEPDs with a designed CSQW and the conventional QW structure. The fabricated CSQW-RCEPD exhibits a maximum quantum efficiency of 45.4%, an improvement of 36.2% in comparison with the conventional RCEPD. Moreover, the spectral bandwidth is 4.7 nm in the CSQW-RCEPD, which is in good agreement with the calculated result. The RCEPD with enhanced light absorption using a CSQW structure is highly promising for optical interconnect and sensing applications.</P>

Nanoplasmon-Enhanced Light Emitter for AC Plasma Display Panels With Large Scalability

Seong Min Lee,Young Kwan Kim,Min Kyu Kim,Hyoung-Bin Park,Kyung Cheol Choi Institute of Electrical and Electronics Engineers 2012 IEEE transactions on electron devices Vol. No.

<P>We demonstrate for the first time a large-scale ac plasma display panel enhanced by localized surface plasmon (LSP) resonance owing to Ag nanoparticles. In order to generate plasmon resonance fitted to the blue-emitting phosphor, we deposited Ag nanoparticles on the phosphor layer by a spray method using large-scale fabrication technology. Localized surface plasmon resonance by Ag nanoparticles was strongly induced at the blue-emission regime. The measurement of the optical and electrical properties revealed that the enhanced emission from the phosphor was reflected in luminous efficacy enhanced by an average of 17.8% in manufactured test display panels. The improved luminous efficiency originated from the resonant coupling between the LSPs of the Ag nanoparticles and the electric-dipole transition of europium ions responsible for blue emission.</P>

Design Method of an Ultrahigh Speed PM Motor/Generator for Electric-Turbo Compounding System

Jung, Dong-Hoon,Lee, Jae-Kwang,Kim, Jun-Young,Jang, Ik Sang,Lee, Ju,Lee, Ho-Joon Institute of Electrical and Electronics Engineers 2018 IEEE transactions on applied superconductivity Vol.28 No.3

<P>This paper presents the design of an ultrahigh speed permanent magnet (PM) motor/generator driven at a rated output and speed of 10 kW and 70 000 r/min, respectively, for use in an electric-turbo compounding system. When designing the very-high speed motor/generator, the mechanical and structural safety of the rotor and losses that occur when the motor operates at high speed should be considered for safe operation. In this paper, the optimal design of the ultrahigh speed PM motor is performed with finite element analysis and structural analysis. Especially, the electromagnetic and structural characteristics based on the sleeve material are analyzed. The optimal design for PM motor, using carbon fiber is proposed not only to reduce the eddy-current loss, which prominently occurs at very-high speed, but also to ensure its structural safety. Finally, the validity of the design method and the effectiveness of the fabricated prototype of PM motor is verified through experimental tests.</P>