A fast feedback controlled magnetic drive for the ASDEX Upgrade fast-ion loss detectors

Abstract

A magnetically driven fast-ion loss detector system for the ASDEX Upgrade tokamak has been designed and will be presented here. The device is feedback controlled to adapt the detector head position to the heat load and physics requirements. Dynamic simulations have been performed taking into account effects such as friction, coil self-induction, and eddy currents. A real time positioning control algorithm to maximize the detector operational window has been developed. This algorithm considers dynamical behavior and mechanical resistance as well as measured and predicted thermal loads. The mechanical design and real time predictive algorithm presented here may be used for other reciprocating systems.

First measurements of a scintillator based fast-ion loss detector near the ASDEX Upgrade divertor

“…This new detector improves the poloidal coverage of fast-ion losses on ASDEX Upgrade, which will be completed with the recently installed magnetically driven FILD4. 14…”

First measurements of a magnetically driven fast-ion loss detector on ASDEX Upgrade

“…A retaining spring holds the system back when not used. Coil rotation is given by balance between retaining spring torque, coil torque and coil and probe head inertias [5]. The coil (placed on an electrically insulated holder) is energized by a power supply controlled in real-time by the discharge control system.…”

“…Aiming at improving the poloidal coverage of this suite, a fifth FILD (labelled FILD4) was deployed in a remote position (∼ 45 • below the mid-plane) where port unavailability prevents from using a conventional FILD design that is driven by an out-vessel step motor. An in-situ concept [5][6][7][8] in which probe head motion is provided by an externally energized coil, is applied, allowing easier vessel installation, radial fast-ion loss profiles and opening the door for real-time control of probe head insertion, to use FILD in a wider range of operation parameters.…”

A fast model to resolve the velocity-space of fast-ion losses detected in ASDEX Upgrade and MAST Upgrade

“…The accomplishment of real-time fast-ion loss velocity-space measurements does not only accelerate the analysis of the FILD data. In future works, this information can be also used as an input to the real-time control of the FILD positioning [14] and the active control of MHD events [15].…”