Electromagnetic transients simulation using a shell approach for ITER cCXRS upper port plug due to plasma vertical displacement events

Transient electromagnetic (EM) analysis is presented focusing on main components of the ITER core charge exchange recombination spectroscopy (cCXRS) port plug developed by Forschungszentrum Jülich (FZJ), ITER-NL and UKAEA(CCFE) in 2009. The cCXRS primary function is to transfer the light in the visible part of spectra emitted by interaction of the plasma ions with a diagnostic neutral beam.The TYPHOON software package has been used for the EM analysis. The code is dedicated for simulation of transient electromagnetic processes using a shell approach in the integral–differential formulation to represent conducting structures with a set of multi-connected shells arbitrary located in a space. The advantage of the shell approach is a higher flexibility in modelling detailed structures as compared with widely used 3D models. On the other hand, the shell approach requires ultimate care in modelling relatively thick structures. These issues are discussed in the paper.Two vertical displacement events (VDE) which seem to result in the largest EM loads on the main cCXRS components have been agreed with FZJ and simulated. Transient electromagnetic processes caused by different sources have been considered separately, and then superimposed to obtain the total solution. Three types of transient processes for each type of VDE have been analyzed: (1) due to variations of a toroidal plasma current, shape and position and due to variations of poloidal field coils (PFC) and central solenoid (CS) currents, (2) due to variations of the Halo current and (3) due to variations of a toroidal magnetic flux of plasma. The analysis covers two options for electrical contact between the main shell (MS) of the port plug and the blanket shield module (BSM).The results are supposed to be used for benchmarking with independent 3D EM models developed for the upper port plug.