29th Symposium on Fusion Technology (SOFT 2016)

P1.055 Conceptual design and dynamic simulation of a fast-ion loss detector for ITER

5 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 55

Poster D. Diagnostics, Data Acquisition and Remote Participation P1 Poster session

Speaker

Juan Ayllon (CNA)

Description

Scintillator based fast-ion loss detectors (FILD) are used in virtually all major tokamaks and stellarators to study the fast-ion losses induced by magnetohydrodynamic (MHD) fluctuations. FILD systems provide velocity-space measurements of fast-ion losses with alfvenic temporal resolution. This information is crucial to identify the MHD fluctuations responsible for the actual fast-ion losses and to understand the wave-particle interaction underlying the transport mechanism. The ITPA Topical Group on Energetic Particles has selected a FILD as the most preferred diagnostic for fast-ion loss measurements in ITER. In response to this prioritization, the Port Plugs and Diagnostics Integration Division at ITER Organization (IO) initiated an effort to develop a conceptual design of a reciprocating FILD in ITER. The extreme working conditions expected in ITER impose especial and unique requirements for such a system. A fast and reliable motion of the detector head, with approx. 10 cm diameter and 20 cm stroke, is mandatory to obtain meaningful measurements of fusion born alpha particle losses with acceptable thermal loads. The dynamic system has been designed as to avoid disruption halo currents. This fast motion will be controlled by an energized solenoid which will create the needed torque, taking advantage of the tokamak magnetic field. In this contribution, a conceptual mechanical design and a dynamic simulator for the ITER FILD are presented. This simulator models the FILD mechanical behavior as a multi-body system real-time controlled by a proportional-integral-derivative (PID) algorithm. The PID sets the voltage applied to the solenoid depending on the actual and target position in real time. Aspects such as friction in joints are taken into account in the model, allowing to determine reaction forces under high friction conditions, as those related to in-vacuum environments. Simulation results describing the detector dynamic performance and mechanical strength under several working scenarios will be presented.