• H. S. Kim, Y.-S. Cho, I.-S. Hong, D. I. Kim, H.-J. Kwon, K. T. Seol, Y.-G. Song
  KAERI, Daejon

The RF amplitude and the phase stability requirements of the LLRF system for the PEFP(Proton Engineering Frontier Project) proton linac are within 1% and 1 degree, respectively. As a prototype of the LLRF, a simple digital PI control system based on commercial FPGA board is designed and tested. The main features are a sampling rate of 40 MHz which is four times higher than the down-converted cavity signal frequency, digital in-phase and quadrature detection, pulsed mode operation with the external trigger, and a simple proportional-integral feedback algorithm implemented in a FPGA. The developed system was tested with 3 MeV RFQ and 20 MeV DTL, and satisfied the stability requirements.

• K. T. Seol, Y.-S. Cho, D. I. Kim, H. S. Kim, H.-J. Kwon
  KAERI, Daejon

The PEFP LLRF system for the 3MeV RFQ and 20MeV DTL has been developed. The stability of ±1% in the amplitude and ±1˚ in the phase is required. Therefore, the drift of the analog components should be low to satisfy the requirement. Analog chassis as a prototype of LLRF system is configured and tested. RF components including an IQ modulator, an RF switch, a mixer, phase comparators, RF splitters, RF filters and trip circuit for high VSWR are installed in this chassis. This performs the shift of RF amplitude and phase from IQ signal, down-conversion to 10MHz IF signal, interlock for arc and high VSWR, and RF/clock distribution. The amplitude and phase stability of each component are measured to check the effect on the whole system performance. The detailed configuration and test results are presented.

• K. R. Kim, W. H. Hwang, H. S. Kim, H.-G. Kim, S. J. Kwon, J. Park, J. C. Yoon
  PAL, Pohang, Kyungbuk
• Y.-S. Cho, H.-J. Kwon
  KAERI, Daejon

The temperature-controlled cooling water system was designed to obtain the resonance frequency stabilization of the normal conducting drift tube linac (DTL) for the PEFP 100 MeV proton accelerator. The primary sizing of individual closed-loop low conductivity cooling water pumping skids for each DTL system was conducted with a simulation of thermo-hydraulic network model. The temperature control schemes incorporating the process dynamic model of heat exchangers were examined to regulate the input water temperatures into the DTL during the steady state operation. The closed water circuits to achieve system performance and stability for low and full duty operation modes were discussed, and numerical results were also presented.

• K. R. Kim, Y.-S. Cho, I.-S. Hong, H. S. Kim, B.-S. Park, S. P. Yun
  KAERI, Daejon
• H. J. Kim, J. H. So
  Kyungpook National University, Daegu

The test beam line was installed at the MC-50 cyclotron of KIRAMS (Korea Institute of Radiological And Medical Sciences). It has been supporting many pilot and feasibility studies on the development of beam utilization technologies of PEFP (Proton Engineering Frontier Project). The energy measurement with high accuracy is very important for the some experiments such as radiation hardness test of semiconductor devices, nuclear physics, detector test, etc. SSB and Si(Li) detector was used as del-E and E detector and the thickness of detectors are 2mm and 5mm each. The available energy range is 10MeV~39MeV and the flux was controlled not to be exceed 1·10⁺⁰⁵/cm²-sec using a 0.5mm diameter collimator.

• H.-J. Kwon, Y.-S. Cho, I.-S. Hong, J.-H. Jang, D. I. Kim, H. S. Kim, K. T. Seol
  KAERI, Daejon

The beam test of the Proton Engineering Frontier Project (PEFP) 20 MeV proton linear accelerator started again, after the upgrade of the RF control system, One of the important goals of the test is to increase the beam current to the design level. Tuned current transformers were installed along the DTL tanks to measure the beam current itself and possible beam loss along the accelerator. Because there were no empty drift tubes, the current transformers should be installed between DTL tanks. Therefore, the tuning plans were developed to obtain the desired beam properties with the limited number of beam diagnostic devices. Also two BPMs for the time of flight measurement and energy degrader were installed at the end of the 20 MeV accelerator to measure the beam energy. In this paper, the overall test results including beam current and energy measurement are presented.