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발전기의 위상잡음 감소를 위한 DGS 공진기 설계 및 제작
설경태,조영빈,전계석 경희대학교 산학협력기술연구원 2002 산학협력기술연구논문집 Vol.8 No.-
In this paper, a novel resonator is designed using the resonant characteristic of the defected ground structure(DGS) from phase noise reduction in oscillator. To confirm the validity of the designed DGS resonator, two kinds of oscillators using DGS resonator and λ/4 microstrip line have been designed and measured in the same configuration except for the configuration of the resonator for the examination of the reduction of phase noise by the DGS. At the fundamental frequency of 8.6GHz, 4.83 dBm output power and -91.7 dBc @100kHz phase noise have been measured for oscillator with DGS resonator, and 5 dBm output power and -72.78 dBc @100kHz phase noise have been measured for one with λ/4 microstrip line. Measurement shows reduced phase noise by 18.92 dB in oscillator with DGS resonator compared to one with λ/4 microstrip line.
RF Phase Stability in the 100-MeV Proton Linac Operation
설경태 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3
The 100-MeV proton linac of the Korea multi-purpose accelerator complex (KOMAC) has beenoperated to provide a proton beam to users. The 100-MeV linac consists of a 3-MeV radio-frequencyquadrupole accelerator (RFQ), four 20-MeV drift-tube linac (DTL) tanks, two medium-energybeam-transmitter (MEBT) tanks, and seven 100-MeV DTL tanks. The requirements of the fieldstability are within ±1% in RF amplitude and ±1 degree in RF phase. The RF phase stabilityis influenced by a RF reference line, RF transmission lines, and a RF control system. The RFreference signal is chosen to be a 300-MHz local oscillator (LO) signal, and a rigid copper coaxialline with temperature control was installed for an RF reference distribution. A phase stability of±0.1 degrees was measured under a temperature change of ±0.1◦C. A digital feedback controlsystem with a field-programmable gate-array (FPGA) module was adopted for a high RF stability. The RF phase was maintained within ±0.1 degrees with a dummy cavity and was within ±0.3degrees at RFQ operation. In the case of the 20-MeV DTL tanks, one klystron drives 4 tanks, andthe input phases of 4 tanks were designed to be in phase. The input phases of 4 tanks were fixedwithin ±1 degree by adjusting a phase shifter in each waveguide.
Design and Fabrication of the High-power RF Transmission Line into the PEFP Linac Tunnel
설경태,권혁중,김한성,조용섭 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.2
The 100-MeV proton linear accelerator (linac) for the Proton Engineering Frontier Project (PEFP) has been developed and will be installed at the Gyeong-ju site. For the linac, a total of 11 sets of RF systems are required, and the waveguide layout was fixed to install high-power RF (HPRF) systems. One of the important interfaces with the building construction is the high-power radio-frequency (HPRF) transmission line embedded in the tunnel, which is used to transmit 1-MW RF power to each cavity in the tunnel. The waveguide section penetrating into the linac tunnel was designed with a bending structure for radiation shielding, and the dependence of its voltage standing-wave ratio (VSWR) on the chamfer length of the bending was calculated. The HPRF transmission line was fabricated into a piece of waveguide to prevent moisture and any foreign debris inside the 2.5-m thick concrete block. Air leakage was checked with a pressure of 0.25 psig of nitrogen gas, and a maximum VSWR of 1.196 was obtained by measuring the vector reflection coefficients with the quarter-wave transmission section. In this paper, the design and the fabrication of the HPRF transmission line into the PEFP linac tunnel are presented.
Improvement of the Low-level RF Control System for the PEFP 100-MeV Proton Accelerator
설경태,권혁중,김한성,Young-Gi Song,조용섭 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22
The 100-MeV proton linear accelerator of the Proton Engineering Frontier Project (PEFP) has been developed, and the low-level radio frequency (LLRF) control system for the PEFP 100-MeV accelerator has also been developed. A field stability within ±1˚ in the RF phase and ±1% in the RF amplitude is required in the LLRF control system. The prototype LLRF control system was developed and had been operated for the 20-MeV accelerator, but it was necessary to improve the LLRF control system for 100-MeV accelerator operation. For field stability and stable pulse operation of the 1.5-ms pulse width and a 60-Hz repetition rate (duty of 9%), the control scheme of the direct intermediate frequency (IF) signal output from a field programmable gate array (FPGA) board was adopted, and the commercial FPGA board and the LLRF analog system were changed. The IF and the local oscillator (LO) frequency for the feedback control were chosen as 50-MHz and 300-MHz respectively, and the sampling rate for the in-phase, quadrature (IQ) detection was kept at 40-MHz. In the test with a dummy cavity, the RF amplitude and phase were maintained within ±0.1% and ±0.1˚, respectively, for a pulse width of 1.5-ms and a repetition rate of 60-Hz. In the 20-MeV accelerator operation, a field stability within ±0.6% in the RF amplitude and ±0.3˚ in the RF phase was measured.
Design and Fabrication of the Beam Position Monitor for the PEFP Linac
권혁중,김한성,설경태,류진영,장지호,조용섭 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.4
The beam position monitor (BPM) is an essential component for the PEFP 100-MeV linac’s commissioning. A prototype stripline-type linac BPM was designedfor this purpose. The electrode aperture is 20 mm in diameter, and the electrode is 25mm long, so it can be installed between Drift Tube Linac (DTL)101 and DTL102, which is the shortest distance. One end of the electrode is connected to the Sub Miniature Type A (SMA) feed through for signal measurement, and the other end is terminated as a short. The signal amplitude of the fundamental component was calculated and compared with that of the second harmonic component. The designed BPM was fabricated and a low-power RF test was conducted. In this paper, the design, fabrication and low power test of the BPM for the PEFP linac are presented.
SRF Linac for Future Extension of the PEFP
김한성,권혁중,설경태,장지호,조용섭 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.2
A study on the superconducting RF linac is underway in order to increase the beam energy up to 1 GeV by extending theProton Engineering Frontier Project (PEFP) 100-MeV linac. The operating frequency of the PEFP superconducting linac(SCL) is 700 MHz, which is determined by the fact that the frequency of the existing normal conducting linac is 350 MHz. Apreliminary study on the beam dynamics showed that two types of cavities with geometrical betas of 0.50 and 0.74 couldcover the entire energy range from 100 MeV to 1 GeV. An inductive output tube (IOT) based RF system is underconsideration as a high-power RF source for the SCL due to its low operating voltage and high efficiency. As a prototypingactivity for a reduced beta cavity, a five-cell cavity with a geometrical beta of 0.42 was designed and fabricated. A vertical testof the prototype cavity at low temperatures was performed to check the performance of the cavity. The design study and theprototyping activity for the PEFP SCL will be presented in this paper.
Beam Phase Measurement of the PEFP 20-MeV Proton Accelerator
권혁중,김한성,설경태,Young-Gi Song,장지호,조용섭 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22
A 20-MeV proton accelerator has been developed and tested at the Korea Atomic Energy Institute (KAERI) by the Proton Engineering Frontier Project (PEFP). Beam phase was measured at the end of the 20-MeV accelerator by using the beam position monitor (BPM) signal. The beam current and phase were measured by changing the relative RF phase between the 3-MeV radio frequency quadrupole (RFQ) and the 20-MeV drift tube linac (DTL), and the results were compared with those simulated by using the PARMILA code. In this paper, the beam phase measurement results are presented, and the phase scan results based on the normal operating condition are compared with the simulation results.