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Sungsu Cha,Yujong Kim,Jinsik Ju,Youngwoo Joo,Byeong-No Lee,Soo Min Lee,Jae Hyun Kim,Pikad Buaphad,Byung Cheol Lee,Hyungki Cha,Jang Ho Ha,Hyung Dal Park,Ki Beak Song,Seung Hyun Lee,Heesoo Kim 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.6
The Korea Atomic Energy Research Institute (KAERI) has been developing a Container Inspection System (CIS) by using a dual-energy (9/6 MeV) S-band (= 2856 MHz) electron linear accelerator. The key components of the CIS are the electron linear accelerator (including an electron gun, an accelerating structure, an RF power source, cooling chillers, vacuum pumps, magnet power supplies, and two solenoid magnets with beam focusing and shielding functions), a tungsten target for X-ray generation, an X-ray collimator, a detector array, and a container moving system. Generally, in accelerators, beam focusing is mainly done by solenoids operating in the region of a few MeV to keep the shape of transverse beam symmetrically round so as to reduce the loss of electrons, which increases the beam current and the beam power. In addition, a specially-designed component is needed to protect against the radiation due to the lost electrons. In this paper, we describe the design, fabrication, and optimization of two specially- designed solenoids with focusing and radiation shielding functions for a dual-energy S-band electron linear accelerator for a CIS.
Development of a Dual-pulse RF Driver for an S-band (= 2856 MHz) RF Electron Linear Accelerator
Sungsu Cha,김유종,Byeong-No Lee,Byung Cheol Lee,Hyungki Cha,Jang Ho Ha,박형달,Seung Hyun Lee,Hui Su Kim,Pikad Buaphad 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.8
The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW − 9 MeV) and 37 W (3.4 MW − 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.
송규석,Cha Hyungki,최인희,Jung Euo Chang,유희수 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.1
The isotopic composition of trace Yb and Pd in solution phase were determined by adopting laser ablation time-of-flight mass spectrometry and adsorbing samples onto metal plates, such as stainless steel, copper, and molybdenum. Ion signals from the Yb isotopes were observed easily with a reasonable mass resolution for standard solutions of 1 ppb to 1000 ppb. The minimum detectible concentration of Yb using this technique was estimated to be less than 1 ppb. Laser ablation mass spectrometry of the PdCl2 adsorbed onto a copper plate revealed various copper clusters with chloride ions such as, Cu2Cl, Cu3Cl2, Cu4Cl3, Cu2, Cu3, etc. The observation of palladium ion peaks in the laser ablation mass spectra was found to depend on the reaction time between the copper plate and the PdCl2 solution. These clusters were identified as being generated during the laser ablation process, not during the chemical reactions in the solution phase.la
Kim, Dukhyeon,Cha, Hyungki Optical Society of America 2006 Optics letters Vol.31 No.19
<P>Aerosols are important parameters in the meteorological and environmental fields, and remote aerosol identification is extremely desirable. We have proposed and designed a two-wavelength (355 and 532 nm) rotational Raman and elastic lidar that can measure the wavelength dependence of the aerosol backscattering coefficient without any assumptions about the Angström coefficient or the overlapping function from low (100 m) to high (10 km) altitude, depending on the weather conditions. We have measured the differences in the backscattering ratios (BRs) among a cloud, aerosol in the boundary layer, and Asian dust. The ratio of the aerosol backscattering coefficients between two wavelengths is a fingerprint of an aerosol, which is similar to the Angström coefficient. The BR value for a typical aerosol ranged from 0.56 to 0.4 in the boundary layer and from 0.5 to 0.1 for Asian dust. The BR value of water droplet was not unique but was spread over a wide range because of its size distributions.</P>