EPJ Web of Conferences (Jan 2015)

Beam propagation and stray radiation in the ITER EC H&CD Upper Launcher

  • Platania Paola,
  • Bruschi Alex,
  • Farina Daniela,
  • Figini Lorenzo,
  • Goodman Timothy,
  • Krause Alexandra,
  • Henderson Mark A.,
  • Moro Alessandro,
  • Saibene Gabriella,
  • Toussaint Matthieu,
  • Sozzi Carlo

DOI
https://doi.org/10.1051/epjconf/20158702018
Journal volume & issue
Vol. 87
p. 02018

Abstract

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The four ITER Electron Cyclotron Upper Launchers (UL) are designed to control Magneto- Hydrodynamic instabilities with the deposition of Electron Cyclotron power. According to the present design, each launcher comprises two rows of four input waveguides, whose output beam is focused and driven towards the plasma by four sets of mirrors. In order to study the beam-launcher interaction throughout quasi-optical propagation, with particular attention to straylight behaviour, and to verify analytical calculations, a 3D model of the UL optical system has been implemented with the electromagnetic code GRASP® and the Physical Optics method. Detailed description of the components are introduced: pure hybrid mode HE11 from cylindrical waveguide as input beams, real shapes of the mirror contours, semi-analytical description of the ellipsoidal surfaces of focussing mirrors. A conceptual calculation scheme has been developed in order to take into account not only the direct contribution of the single source on its next scatterer but also the first order indirect effects: crosstalk from different lines of the same row and crosstalk from different rows have been evaluated after reflection on the first and third set of mirrors. The evaluations presented have been performed on the preliminary UL design, the last major milestone before finalization; however, the numerical model is suitable to be applied to future evolutions of the setup and/or other configurations.