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Adelmann, A.

Paper Title Page
MOPD55 A Field Emission and Secondary Emission Model in OPAL 207
  • C. Wang, A. Adelmann, Y. Ineichen
    PSI, Villigen

Dark current and multipacting phenomena, have been observed in accelerator structures, and are usually harmful to the equipment and the beam quality. These effects need to be suppressed to guarantee stable operation. Large scale simulations can be used to understand the origin and develop cures of these phenomena. We extend OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines with the necessary physics to simulate multipacting phenomena. We add a Fowler-Nordheim field emission model and secondary emission model, as well as 3D boundary geometry handling capabilities to OPAL. These capabilities allows us to evaluate dark current and multipacting in high-gradient linac structures and in RF cavities of high intensity Cyclotrons. The electric field in present accelerator structures is high enough, such that space charge effects in the Fowler-Nordheim model can not be neglect. First a Child-Langmuir model is added to phenomenologically model space charge limited field emission. In a second step a space charge solver capable of handling complicated boundary geometries will be implemented to make our field emission model more self-consistent.

TUO2A03 Challenges in Simulating MW Beams in Cyclotrons 295
  • Y.J. Bi
    Tsinghua University, Beijing
  • A. Adelmann, R. Dölling, J.M. Humbel, W. Joho, M. Seidel
    PSI, Villigen
  • C.-X. Tang
    TUB, Beijing
  • T.J. Zhang
    CIAE, Beijing

The 1.3 MW of beam power delivered by the PSI 590 MeV Ring Cyclotron together with stringent requirements regarding the controlled and uncontrolled beam losses poses great challenges with respect to predictive simulations. A new particle matter interaction model in OPAL is taking into account energy loss, multiple Coulomb scattering and large angle Rutherford scattering. This model together with the 3D space charge will significantly increase the predictive capabilities of OPAL. We describe a large scale simulation effort, which leads to a better quantitative understanding of the existing PSI high power proton cyclotron facility. The initial condition for the PSI Ring simulations is obtained from a new time structure measurements and the many profile monitors available in the 72 MeV injection line. A large turn separation and narrow beam size at the extraction turn is obtained. We show that OPAL can precise predict the radial beam pattern at extraction with large dynamic range (3-4 orders of magnitude). The described capabilities are mandatory in the design and operation of the next generation high power proton drivers.


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