Sensorics in the Fusion Group
Sensorics concerns the development of advanced measuring technologies for fusion reactors, with the aim to use these measurements as input for a real time control system. This is extremely challenging for a fusion plasma with a temperature of a few hundred million K.
Presently, the group is deeply involved in the development of a system to measure the ion temperature and plasma motion in ITER. The system is based on a technique called Charge Exchange Recombination Spectroscopy (CXRS), which is one of our specialization areas. This is done with an international consortium and is expected to lead to the installation of this system in ITER. Already, a prototype ultra-sensitive spectrometer was developed and constructed with TNO. This has been operated – by way of test – in the Asdex-Upgrade experiment in the Max-Planck Institute for Plasma Physics in Garching. One of our PhD-students in Garching used this instrument to determine the transport of helium in the fusion plasma. Now the instrument will be coupled to the new large W-7x experiment in Greifswald and manned with another of our PhD students. Several master students have already done their internships in this field.
With this prototype instrument the dream to analyze the complex data real-time, on-the-board so to speak, and make it available to a control system is pursued. Low latency and high reliability are the key requirements here, and our in house specialists are taking on this challenge.
A somewhat similar technology is employed to measure the distribution of currents and magnetic field in the hot plasma. This measurement is based on the motional Stark-effect (MSE). Because of our expertise in this field, the team of the Korean tokamak KSTAR asked us to lead the development of their MSE system. Here too, the real time analysis is an important element of the system. In this collaboration several students from the TU/e do projects in Korea and a PhD is full-time working on this.
Sensorics play a crucial role in another system for ITER, the high-power microwave injection system for the stabilization of mhd-modes. The sensor of this real time, active control system employs microwaves as well. The original, proof-of-principle demonstration that the picowatt signal from the plasma could be measured using the same antenna that sends the Megawatt beam into the plasma, was demonstrated by some of our group members at the former German tokamak TEXTOR. The mhd-control by microwave power is presently vigorously pursued by the collaboration of the TU/e control systems group and Differ.
Through a collaboration with the inspirational W7-X stellarator project of the Max-Planck institute in Greifswald, our students are also involved in a variety of microwave experiments.