Closed-loop Control of the Safety Factor Profile in the TCV Tokamak
53rd IEEE Conference on Decision and Control
Los Angeles, California, USA, December 15-17, 2014
| Abstract |
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A key property that has a close relationship to both the performance and stability of the plasma in nuclear fusion tokamak devices is the safety factor profile (q-profile). As a result, extensive research has been conducted to develop algorithms to actively control the evolution of the q-profile with the goal of optimizing the tokamak approach to nuclear fusion energy production. The actuators that can be utilized to control the q-profile are the total plasma current, the auxiliary heating/current-drive system and the line-average electron density. In this work, we first investigate the effect that the control input direction associated with pure plasma heating has on the q-profile in low performance (L-mode) operating scenarios in the TCV tokamak. Secondly, we design feedback controllers that utilize the total plasma current and exclusively the current-drive capabilities of the auxiliary sources to control the q-profile in L-mode scenarios in TCV. The controllers are designed to put emphasis on achieving the target q-profile in different spatial regions as well as to respond differently to errors in the q-profile. The control performance of each controller is tested with the simplified physics-based plasma profile simulation code RAPTOR. The comparison of the closed- loop performance of these controllers is done in preparation for future q-profile control experiments in the TCV tokamak.