Pattern calculations for Dogleg configuration

We report detailed calculations of the launched beam shape for the final Remote Steering configuration of the ECRH Upper Launcher, using Physics Optics method for toroidal and football- shaped mirrors. The chosen option for the Remote Steering launcher is the Dogleg design (developed by the FOM Institute [6]) in which two double curvature mirrors for each couple of rows (upper and lower) are used. Two configurations of the system have been studied with the electromagnetic code GRASP9 [1] to follow the upgrade in the design developed by FOM. The design model has been refined to improve the performances of the launching system, in particular to reduce the beam width and the astigmatism; the changes regards the surface curvatures, mirror and source positions and steering ranges. Within the calculation regarding the first configuration (design version March 2005) the finite size effect of the mirrors have been studied, while in the second case (design version August 2005) the rim definition has been improved by designing it in such a way that the contour levels corresponding to 1.5 times the beam width at -8.7 dB are included. The results show a relevant deformation and elongation of the beams at the target in the poloidal direction, especially at one extreme of the steering range (+7° for the Lower row and +12° for the Upper row). The diffraction effect from the edges of mirrors results to be negligible for the main beam, while significant deformation arises at the level of -30dB with respect to the maximum. The increasing of the local power on the mirrors surface due to overlapping of the beams has been considered in a few example cases.