Speaker
Alessandro Formisano
(Dept. of Industrial and Information Engineering)
Description
The magnet system in ITER is composed by three main coils groups, characterized by tight tolerances on manufacturing and assembly, to keep error fields at levels compatible with plasma operation. Additional coils correct error fields guaranteeing suitable accuracy at start of flat top [1].
Plasma initiation in ITER will be critical, since low electric field will be available, and a reduction of field lines connection length may occur due to stray fields [2]. A number of studies have been performed to assess impact of different stray field sources, but they mostly used equivalent 2D models to assess effects of intrinsically 3D fields [3], or were performed on other machines run in “ITER-relevant” modes.
Magnet tolerances will provide local contributions to stray field at breakdown in the order of some mT, whose effects must be assessed using 3D models. The toroidally averaged figures are much smaller (in the order of fractions of mT), but impact in terms of e.g. connection length of localized field map deformations may provide deeper understanding of field at breakdown.
In this paper, starting from a waveform scenario optimized using a axi-symmetric model for nominal coils and vessel, a full 3D numerical model is used to analyse the contribution to magnetic field in the breakdown region due to tolerances on coils, including toroidal field coils. Advantage is taken from semi-analytical parallel computing routines for high accuracy field computation, and two fast, 3D line-tracing algorithms are used to assess average stray fields and connection length reduction.
[1] ITER EFDA Documentation Series No.24, “ITER Technical Basis”, Chapter 3.7.4.1.3
[2] Gribov Y. Et al., “Chapter 8: Plasma operation and control”, Progress in the ITER Physics Basis, Nuclear Fusion 47 (2007), S385.
[3] A. B. Mineev et al., “Study of ITER First Plasma Initiation using a 3D Electromagnetic Model”, FEC 2014.
Co-authors
Alessandro Formisano
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Alfredo Pironti
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Fabio Villone
(Dept. of Automation, Electromagnetism, Information Engineering and Industrial Mathematics, Univ. Di Cassino e del Lazio Meridionale, Cassino (FR), Italy)
Francesco Ledda
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Francesco Pizzo
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Giuseppe Ambrosino
(Dept. Of Electric Engineering and Information Tehcnology, Univ. Di Napoli “Federico II”, Napoli, Italy)
Joe Snipes
(ITER Organization, St. Paul-Lez-Durance, Cadarache, France)
Luca Zabeo
(ITER Organization, St. Paul-Lez-Durance, Cadarache, France)
Massimiliano De Magistris
(Dept. Of Electric Engineering and Information Tehcnology, Univ. Di Napoli “Federico II”, Napoli, Italy)
Massimiliano Mattei
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Peter De Vries
(ITER Organization, St. Paul-Lez-Durance, Cadarache, France)
Raffaele Albanese
(Dept. Of Electric Engineering and Information Tehcnology, Univ. Di Napoli “Federico II”, Napoli, Italy)
Raffaele Martone
(Dept. of Industrial and Information Engineering, Seconda Università di Napoli, Aversa (CE), Italy)
Yuri Gribov
(ITER Organization, St. Paul-Lez-Durance, Cadarache, France)
