Author: Park, S.J.
Paper Title Page
MOPC033 The Status of a 1.6-cell Photocathode RF Gun at PAL 142
 
  • M.S. Chae, J.H. Hong, I.S. Ko, Y.W. Parc
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The RF power conditioning of the photocathode RF gun with four holes at the side of the full cell named as 'Pohang gun' is in progress. The first goal of the conditioning is the operation of the gun with RF pulse width of 1.5 μm, repetition rate of 30 Hz, field gradient at the cathode of 130 MV/m. We operated the RF gun successfully with the conditions within last few months. It was first operational experience with such conditions in PAL. Now we have a plan to operate RF gun with higher repetition rate up to 60 Hz.  
 
MOPS035 Energy Spreads by Transient Beam Loading Effect in Pulsed RF Linac 679
 
  • S.H. Kim, M.-H. Cho, G. Ha, H.R. Yang
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • W. Namkung, S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • J.-S. Oh
    NFRI, Daejon, Republic of Korea
 
  Funding: Work partly supported by KAPRA and POSTECH Physics BK21 Program
RF linacs for high power beams are operated in the fully beam-loaded condition for the power efficiency. In this condition, temporal energy spreads are induced by the transient beam loading effect. Irradiation sources require the beam energy of less than 10 MeV to prevent undesirable neutron production. In order to maximize the beam power and maintain the beam energy in a safe value, we need to suppress the temporal energy spreads. In an L-band traveling-wave linac for irradiation sources, the high energy electrons are suppressed by the beam current modulation with the RF power modulation. As a result, the average beam energy and the corresponding beam power are improved by nearly 60% compared to the case without any modulations.
 
 
WEPC018 Self-focusing Effects in Compact C-band Standing-wave Accelerating Structure for X-ray Imaging Applications 2046
 
  • H.R. Yang, M.-H. Cho, S.H. Kim, W. Namkung, S.J. Park
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • J.-S. Oh
    NFRI, Daejon, Republic of Korea
 
  In electron RF linacs for industrial X-ray imaging applications, compact structures are preferred for mobility. The electron beam spot size of 1 – 2 mm is required for the spatial resolution of images at the X-ray conversion target. Applying self-focusing effects to the accelerating structure, external magnets can be removed and then the accelerator system becomes more compact. We design a C-band electron linac, which is capable of producing 6-MeV, 80-mA pulsed electron beams with an RF power of 1.5 MW. It uses a bi-periodic and on-axis-coupled accelerating structure with a built-in bunching section. It uses the π/2-mode standing-waves. The first bunching cell has an asymmetric geometry which maximizes the RF phase focusing. On the other hand, the normal cells are designed for the electrostatic focusing to be maximized. In this paper, we present design details of the accelerating cells and the beam dynamics simulation by the PARMELA code.