• Title/Summary/Keyword: X-ray generation

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Survey on ultrafast time resolved X-ray diffraction measurements of crystal structure (X선의 초고속 결정구조 측정법)

  • Koo, Y.D.;Kim, Y.C.;Oh, C.S.
    • Journal of Energy Engineering
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    • v.23 no.3
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    • pp.13-16
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    • 2014
  • We have surveyed on significant progress in recent developments of accelerator-based pulsed X-ray sources has offered the opportunity for time-resolved studies on fast structure dynamics on the nanometer scale. The required and currently available techniques for time resolved X-ray diffraction measurements using the third-generation synchrotron radiation sources are summarized. Ultrafast X-ray experimental techniques are discussed for femtosecond studies at future synchrotron radiation sources.

The study on X-ray generation in the Coaxial Plasma focus Device (동축 플라즈마 집속장치에서의 x-선 방출에 관한 연구)

  • 엄영현
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.65-69
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    • 1989
  • Mather type dense plasma focus device was develooped for the feasibili쇼 study in its application to the x-ray lithography. To etermine the electrical characteristics,the temporal begavior of the discharge current and the voltage was measured by using the Rogowski coil and the high voltage probe respectively. The results are 9 $\mu\textrm{s}$ of the period, 18m$\Omega$ of resistance and 0.16$\mu$Η of inductance. The average current sheath velocity was measured by the light signal emitted at the moving plasma sheath. The light signal was detected through two fiber bundles. When the applied voltage was 13 kV and the initial jpressure of argon was 21.8 Pa, the best plasma focus was occurred. The x-ray emission characteristics from the plasma focus was determined by the x-ray pictures taken by pinhole camera. It is focus that the plasma was focused at 1.4 cm distant position above the center electrode and its diameter was about 1.0 m.

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Feasibility study of Hybrid X-ray detecter for Digital X-ray imaging application (디지털 방사선 적용을 위한 Hybrid 방사선 검출기의 Feasibility 연구)

  • Choi, Jang-Yong;Park, Ji-Koon;Lee, Chae-Hun;Lee, Kyu-Hong;Choi, Heung-Kook;Nam, Sang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.04b
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    • pp.77-80
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    • 2004
  • In this study, the purpose is to verified the feasibility to develope Hybrid x-ray detector in order to resolve problems of direct and indirect x-ray detectors. The properties of X-ray detector depend on absorption of X-ray, charge generation by x-ray photon, leakage current. In this study, CdS was used as photoconductor, and $Y_2O_2S:Tb$ as x-ray phosphor was formed on CdS in order to embody Hybrid structure. And Screen printing was used to form Muli-layer. Characteristics of this specimen were analyzed by using SEM, and XRD. And Photoluminescence spectrum of $Y_2O_2S:Tb$, leakage current, with respect to applied voltages, output charge with respect to applied voltages, and X-ray sensitivity were measured. Also, linearity with respect to dose was measured. Leakage current was similar with direct digital x-ray detector, but sensitivity of the hybrid structure is much better than the single-layer structure.

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Simulation of amorphous selenium considering diffraction and interference models (간섭과 회절 모델을 고려한 비정질 셀레늄(a-Se) 시뮬레이션)

  • Kim, Si-hyung;Song, Kwang-soup
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.997-999
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    • 2012
  • Digital X-ray image detector is widely used for radiodiagnosis. Amorphous selenium has been received attention as one of the major material that confirmed photoconductor of direct methode detector. We analysis the photocurrent using 2-dimensional device simulator when blue-ray (${\lambda}=486nm$) is irradiated and high voltage is biased. We evaluate electron-hole generation rate, electron-hole recombination rate, and electron/hole distribution in the amorphous selenium. This simulation methode is helpful to the analysis of digital X-ray image detector. We expect that many applications will be developed in digital X-ray image detector using 2-dimensional device simulator.

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Laboratory Astrophysics using Intense X-ray from Free Electron Lasers

  • Chung, Moses
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.65.4-65.4
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    • 2017
  • The laboratory astrophysics is a new emerging field of basic sciences, and has tremendous discovery potentials. The laboratory astrophysics investigates the basic physical phenomena in the astrophysical objects in controlled and reproducible manners, which has become possible only recently due to the newly-established intense photon and ion beam facilities worldwide. In this presentation, we will introduce several promising ideas for laboratory astrophysics programs that might be readily incorporated in the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). For example, precise spectroscopic measurements using Electron Beam Ion Trap (EBIT) and intense X-ray photons from the PAL-XFEL can be performed to explore the fundamental processes in high energy X-ray phenomena in the visible universe. Besides, in many violent astrophysical events, the energy density of matter becomes so high that the traditional plasma physics description becomes inapplicable. Generation of such high-energy density states can be also be achieved by using the intense photon beams available from the PAL-XFEL.

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Dislocation Analysis of CVD Single Crystal Diamond Using Synchrotron White Beam X-Ray Topography (가속기 백색광 X-Ray Topography를 이용한 CVD 단결정 다이아몬드 내부 전위 분석)

  • Yu, Yeong-Jae;Jeong, Seong-Min;Bae, Si-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.3
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    • pp.192-195
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    • 2019
  • Single-crystal diamond obtained by chemical vapor deposition (CVD) exhibits great potential for use in next-generation power devices. Low defect density is required for the use of such power devices in high-power operations; however, plastic deformation and lattice strain increase the dislocation density during diamond growth by CVD. Therefore, characterization of the dislocations in CVD diamond is essential to ensure the growth of high-quality diamond. In this work, we analyze the characteristics of the dislocations in CVD diamond through synchrotron white beam X-ray topography. In estimate, many threading edge dislocations and five mixed dislocations were identified over the whole surface.

Comparison of Output and Radiation Quality of X-rays according to the Full-Wave Rectification Method and Dual-Voltage Rectification Method of an X-ray Generator (X선 고전압장치의 전파 및 배전압 정류방식에 따른 X선 출력 및 선질 비교)

  • Kim, Tae-Gon;Cheon, Min-Woo;Park, Yong-Pil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.7
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    • pp.534-538
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    • 2010
  • X-ray systems for medical treatment use noninvasive procedures. Being capable of locally inspecting the inside of the body, X-ray systems are routinely used for basic diagnosis. X-ray systems to be used for medical purposes were originally made with a gas filled tube inside an induction coil in the initial stages of development but with this approach it becomes difficult to take a satisfactory picture through thick body sections, non invasively. However continued development made it possible to take non-invasive pictures of breasts, blood vessels and other body parts through thick body sections. Recently, high-voltage X-ray generators of more compact size, increased generation efficiency, and sophisticated output control have become possible. All of these features are made possible by the use of a high-frequency output from an inverter and a fast switching semiconductor device. In this paper, we describe a new X-ray generator operating with a resonant inverter in order to reduce switching loss and high frequency noise. In addition, in order to identify the differences amongst types of rectification, we have compared output and the quality of X-ray pictures obtained with full-wave rectification and dual-voltage rectification methods.

Betatron Radiation of an Off-axis Injected Electron in a Laser Wakefield Accelerator

  • Hwang, Seok-Won;Lee, Hae-June
    • Journal of the Optical Society of Korea
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    • v.13 no.1
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    • pp.86-91
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    • 2009
  • The electrons injected into a laser wakefield undergo betatron oscillation and give rise to the emission of intense X-ray radiation. To investigate the generation conditions of the X-rays, the relativistic motion of an electron injected in an off-axis position has been simulated with wakefield profiles which are pre-calculated with a two-dimensional particle-in-cell code. The wakefield with a plasma density of $1.78{\times}10^{18}\;cm^{-3}$ is generated by the laser with an intensity of $1.37{\times}10^{18}\;W/cm^2$ and a pulse width of 30 fs. From the calculation of the single particle motion, the characteristics of the betatron radiation are investigated in the time domain. As the transverse injection position increases, the power and the duration time of the radiation increase, but the width of each pulse decreases.

Distribution of the Scatter Ray on Chest X-ray Examinations (흉부 X선 촬영 시 산란선 분포 연구)

  • Cho, Pyong-Kon
    • The Journal of the Korea Contents Association
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    • v.12 no.7
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    • pp.255-260
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    • 2012
  • This study aims to examine the generation of scatter rays by dividing it into the presence of the subject at the chest X-ray examination, the X-ray tube and detector in the X-ray room, the front of the patient window, the outside of the entrance door of the patient waiting room, opening of the entrance door, the outside of the radiological technologist's entrance door, and the opening of the radiological technologist's entrance door, etc. When there is a subject, as the subject is thicker, more scatter rays occur at each of the spots for measurement. And when the entrance door is closed at the measurement, fewer scatter rays are generated.

Improvement of detection sensitivity of impurities on Si wafer surface using synchrotron radiation (방사광을 이용한 Si 웨이퍼 표면불순물 검출감도 향상)

  • 김흥락;김광일;강성건;김동수;윤화식;류근걸;김영주
    • Journal of the Korean Vacuum Society
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    • v.8 no.1
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    • pp.13-19
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    • 1999
  • Total reflection X-ray fluorescence spectroscopy using synchrotron radiation source called as TRSFA was explored to achieve high sensitivities to impurity metals on Si wafer surface. It consists of monochromating part to select a specific wavelength, slit part to shield direct beam and to control monochromated beam, and main chamber to dectect fluorescent X-ray counts of impurities on si wafer. Monochromated X-ray of 10.90 KeV was selected and the optimum total reflection condition on silicon wafer was obtained through tuning the dead time and fluorescent X-ray count of Si and Fe. TRSFA system could increase the sensitivity as high as 50 times in comparision with TRXFA using normal X-ray source. But the trend was varied since the surface conditions of Si wafers and, therefore, the reflectivities were different. Furthemore, there seems to be a promising path to reaching a detection limit useful to the next generation metal impurities control, because Fe impurity below to the $5\times10^{9}\textrm{atomas/cm}^2$ can be detectable through the developed TRSFA system.

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