Case study: The next step in carbon-neutral energy production

Description of Fusion

One of the challenges of the 21st century is the energy transition to a carbon-neutral economy.
This could be achieved with solar and wind power. However, these renewable sources are dependent on seasonal changes.
To complement them and advance the transition from fossil fuel-based energy, a weather independent source of energy is needed.
Nuclear fusion offers a clean, sustainable and inexhaustible source of energy. 
 
In short, Nuclear fusion is a process during which two light nuclei are fused together to form heavier elements while releasing energy.
It is the source of almost all energy here on earth: the sun runs on nuclear fusion, converting hydrogen into helium.
The conditions for nuclear fusion can be reproduced in a high temperature plasma reaching 150 million °Celsius.
This can be achieved in experimental nuclear fusion reactors called tokamaks - doughnut-shaped vacuum vessels that use magnetic fields allowing them to contain the hot fusion plasma.
 
Nuclear fusion reactor designs aim to sustain a plasma burn at 150 million °Celsius in their core. Thus, components facing the inner wall must endure operating temperatures of about 1500 °Celsius.
The principle challenge remaining is then to extract the heat energy (for power generation) without exposing sensitive components to either the high heat or particle flux generated by the plasma. 

DIFFER institute and task

At the Dutch Institute for Fundamental Energy Research DIFFER, scientists and engineers work together to develop theoretical models, diagnostic instruments and advanced control systems to safely exhaust power from fusion plasmas. 
DIFFER's approach focuses on employing physics and control theory to spread the exhaust power over a wide area. 
This can be achieved via a collection of atomic and molecular physics processes collectively called plasma detachment.
The challenge is to keep the processes in balance: excessive cooling in the plasma exhaust will disrupt the plasma core and decrease the efficiency of power production, while insufficient cooling will damage the plasma facing components. 

Setup with XIMEA cameras

To achieve detachment, DIFFER collaborated with MIT and EPFL to develop a new diagnostic system called MANTIS, an advanced multispectral narrowband tokamak imaging system.
The MANTIS is equipped with 10x XIMEA cameras from xiX line, simultaneously acquiring quantitative images of intensities of different spectroscopic emission lines.
This allows the researchers to follow different atomic and molecular processes simultaneously.
The images are then used in theoretical models to serve as an input to a model-based detachment controller which can modify the power exhaust in real-time.
 
The technical challenge of MANTIS is to simultaneously acquire and process images on 10 cameras. That is enabled by the Direct Memory Access (DMA) provided by the xiX camera models using PCIe interface technology.
Data delivery is provided at nearly no latency or CPU overhead, so the cores are free to process the incoming data streams. 
 
MANTIS is much more than a multi-camera-system, it is also a part of the control system.
To achieve the control goals, the cameras must deliver real-time performance on the timescale of tens of microseconds and with as little latency as possible.
A single frame freeze could disrupt the balance between sufficient cooling and maximum plasma performance.
This is where the integration becomes difficult…

The optical cavity of MANTIS equipped with the xiX cameras