Nuclear fusion reactor monitored by ten-camera multispectral imaging system

Working with embedded vision cameras from XIMEA, Dutch scientists have developed a multispectral imaging system to study the inside of nuclear fusion reactors during experiments with superheated plasma.

The Plasma Edge Physics and Diagnostics group at the Dutch Institute for Fundamental Energy Research (DIFFER) studies fusion plasmas, the superheated material that allows scientists to fuse the hydrogen isotopes of deuterium and tritium into helium. This fusion reaction also releases energy and neutrons. The plasma is created by heating hydrogen gas to 150 million °C.  

Scientists use a device called a tokamak to control the plasma using powerful magnetic fields. The neutrons created during the fusion reaction strike the walls of the tokamak. This transfer of kinetic energy heats the walls of the tokamak, the heat is used to produce steam, and the steam drives a turbine and creates electricity. For fusion reactions to be sustainable as a long-term source of energy, the walls of a tokamak must be able to survive the tremendous forces released during the fusion reaction.

The researchers at DIFFER use a linear plasma generator called Magnum-PSI to generate plasma and study the interaction between the outer edge of the plasma field and the walls of the plasma generator. To assist in these studies, the researchers developed a camera system called MANTIS (Multispectral Advanced Narrowband Tokamak Imaging System), that is composed of ten MX031 embedded vision cameras and an XS12 switch from XIMEA.

The XIMEA PCIe driver is event-based. The MANTIS system has to synchronize the event triggers of all ten cameras, which required the research team to alter the PCIe driver. Using the camera's Direct Memory Access technology that delivers raw sensor data directly to PC memory, buffers were created to predict the next event after an event is registered and reduce latency between event and image capture.

Light from the plasma enters each camera and strikes a corresponding image sensor. Each sensor is set to detect a different spectral range. By studying the images, the researchers can study the temperature and density of the plasma and the physical and chemical processes that take place in the "scrape-off layer," or the area at which the plasma interacts with the surface of the generator.

Data from the MANTIS system is then fed to a real-time reactor control system. The researchers at DIFFER hope to use this information to assist in design strategies by which to control the reactor, and to better understand power exhaust physics. The MANTIS system has also been used in conjunction with the Swiss Plasma Center's fusion reactor, the Tokamak à Configuration Variable. Chromodynamics,  a spin-off from DIFFER, is also developing commercial applications based on the same technology.

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Share your vision-related news by contacting Dennis Scimeca, Associate Editor, Vision Systems Design

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