Creating and maintaining fusion reactions-a basement of the star-like conditions on Earth-is extremely difficult, and the doctorate Nathan Howard, the chief scientist in the myth of Plasma Science and Fusion Center (PSFC), believes that this is one of the most fascinating scientists of our time. “Both science and the general promise of Fusion as a source of pure energy are really interesting. This motivated me to come to school (in mit) and work in PSFC,” he says.
Howard is a member Magnetic experiments Integrated modeling (MFE-IM) Group on PSFC. Together with the leader of the MFE-IM group, Pablo Rodriguez-Fernandez, Howard and the team use simulation and machine learning to predict how plasma will behave in a fusion device. MFE-IM and Howard research is aimed at forecasting a given technology or configuration performance before it is piloted in a real fusion environment, enabling smarter design choices. To ensure their accuracy, these models are constantly approved using data from previous experiments, maintaining their simulations in reality.
In a recent article on an open access entitled “Forecasting efficiency and turbulence in burning itera plasma“Published in the January issue Nuclear fusionHoward explains how he used the simulations of rotating plasma spinning structures, called turbulence, to confirm that the world's largest experimental fusion device, now under construction in southern France, will operate as expected after turning on. It also shows how a different operational configuration can produce almost the same amount of energy, but with less energy introduction, a discovery that can positively affect the efficiency of fusion devices in general.
The largest and best of what has never been built
Forty years ago, the United States and six other member nations gathered to build ITER (Latin “Road”), a fusion device, which after launching would bring 500 megawatts of fusion power, and a plasma capable of generating 10 times more energy than absorbs from external heating. Plasma configuration designed to achieve these goals – the most ambitious of every merger of the merger – is called the basic scenario, and with the progress of fusion and plasma physics, the methods of achieving this plasma have been improved using more and more stronger simulations, such as modeling Howard.
In his work on verification of the starting scenario, Howard used CGYRO, a computer code developed by Howard's colleagues at General Atomics. CGYRO uses a complex model of plasma physics to a set of defined fusion working conditions. Although this is temporary, CGYRO generates very detailed simulations, how plasma behaves in various locations in a fusion device.
Comprehensive CGYRO simulations were then carried out by Framework portals, a collection of tools originally developed in MIT by Rodriguez-Alnandez. “Portals take on high loyalty (CGYRO) activities and uses machine learning to build a fast model called” surrogate “, which can imitate the results of more complex waveforms, but much faster”, explains Rodriguez-Fernandez. “Only tools for modeling high loyalty, such as portals, give us an insight into the plasma core, before it creates. The approach allows us to create more efficient plasma in a device like itter. “
After the first passage, the accuracy of the replacement was checked in terms of high loyalty, and if the surrogate does not result from the results in accordance with CGYRO, the portals were restarted to improve the replacement as long as it better imitates CGYRO results. “The advantage is that after building a well -trained (replacement) model, you can use it to predict various conditions, with a very reduced need for full complex runs.” After their fully trained surrogates, they were used to examine how various combinations of input data can affect the predicted efficiency of itter and how the basic scenario achieved. In particular, the substitute mileage took a split time and can be used in combination with CGYRO to get an increase and bring detailed results faster.
“I just came to see what my condition was in”
Howard's work with CGYRO, the portal and surrogates examined a specific combination of working conditions, which, as expected, will achieve the starting scenario. These conditions included the magnetic field used, the methods used to control the shape of the plasma, external heating used and many other variables. Using the 14th iteration of CGYRO, Howard was able to confirm that the current configuration of the starting scenario can reach 10 times more output power than the input data to the plasma. Howard talks about the results: “Modeling we have carried out is perhaps the highest possible loyalty at this time and almost certainly the highest published faithfulness.”
14 CGYRO iterations used to confirm the plasma performance included running portals for the construction of replacement models for input parameters, and then binding surrogates with CGYRO for more efficient work. Examination of an alternative scenario that predicted that itter could produce almost the same amount of energy at about half of the input power. The CGYRO model reinforced substantively revealed that the plasma core temperature, therefore, fusion reactions-had no excessive effect on a smaller power input; Smaller power introduction is more efficient. Howard's results are also a reminder that there may be other ways to improve the performance of itera; They just haven't discovered them yet.
Howard reflects: “The fact that we can use the results of this modeling to influence the planning of experiments such as itter is exciting. For years I have been saying that it was the goal of our research, and now, when we do it – it is an amazing bow and really satisfying.”
