This BeCreative minor project is focused on the development of an 3D-printed sensor. This sensor is being
made to help the development of a fusion reactor. There are still issues with a fusion reactor, this BeCreative
project group will try and overcome one of these issues. The issue lies within the diverter, a diverter is a part in
the bottom of the reactor and because of the harsh conditions in the reactor will erode. The sensor that the
group is developing will be used to get more information about this process and maybe come to a conclusion
what other materials, structures or control strategies can be used to increase the lifetime this part of the
reactor. The group is working together with the Dutch Institute for Fundamental Energy Research, they will
help the group with additional information, resources, and equipment.
Because this is a research project the group has made a research question. This question will be answered at
the end of the project. The main research question is: how is it possible to get data of the divertor’s state of
health during the exposure period of plasma? This question will be answered with a few sub questions, these
can be found in chapter 4. Theoretical Research.
A photonic crystal is a repeating structure in which the refractive index changes periodically. The sensor will be
made from a photonic crystal because it can be made to act an electromagnetic wave filter and designed to
resonate at a chosen frequency. By making it out of a single heat resistant material (stainless steel, tungsten)
the photonic crystal will be able to work at high temperatures and due to thermal expansion the resonating
frequency will shift. This shift can be made visible using a network analyser temperature can be derived from it.
This photonic crystal will be made by a metal 3D-printer and the first prototypes will be made with the material
stainless steel 316L. All the testing and measuring will be done on these prototypes, the follow-up project team
to this project is going to make it out of tungsten so much higher temperature can be measured without the
sensor breaking. During this project the photonic crystal will be designed to work between 4-8,5 GHz and
measurements up to 200 °C this is purely because of the available equipment. In the future a sensor can be
designed to work on much higher frequencies and temperatures. In this project the group will purely focus on
proving the concept of using a photonic crystal as a temperature sensor. In the follow-up to this project the
next steps will be detecting material degradation, Ion implantation and magnetic Flux density. But this is out of
scope for this relatively brief research project of 20 weeks
The sensor will be tested by simulations in COMSOL and measurements in an oven and or on a hotplate with
oil. The results that are listed in chapter 7. Results, are in comparison with the simulations in chapter 5.3
COMSOL Design this means that the conclusion is made that the temperature sensor works. There are few
things that can be concluded after these tests, first the photonic crystal is temperature sensitive, and therefore
can be uses as a temperature sensor. Second the results have demonstrate that 3D printing has sufficient
precision and quality to make a microwave photonic crystal. And as last conclusion, the results show an
agreement between theoretical models and experimental results, which indicates that the model can be used
to optimize the designs without first experimentally testing each design.
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