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What would it take to meet global energy needs in a sustainable way in the foreseeable future? Maybe create energy like the sun, thanks to nuclear fusion.
Fission and fusion are very different nuclear reactions, according to Eugenio Schuster, professor of mechanical and mechanical engineering. The fission, which produces the type of nuclear energy created by the reactors on Earth since the 1950s, consists of splitting the nuclei of very heavy elements, such as uranium and plutonium, which triggers a chain reaction difficult to slow, among other reasons. to be dangerous.
Nuclear fusion, on the other hand, is a very difficult reaction to stimulate and maintain. The sun creates energy – in the form of light and heat – by fusing atoms of hydrogen, the lightest gas, using its mbadive gravitational force to confine the hydrogen gas long enough for the nuclear reaction takes place.
On Earth, many scientists believe that the most promising way to create energy through nuclear fusion is to use heat to provoke a similar reaction. This method combines two isotopes of hydrogen, deuterium and tritium, heating them up to 100 million Kelvin, about six times more than the heart of the sun. The kinetic energy of these isotopes is increased by heating, which allows them to overcome the repulsive force due to positive charges (protons) in the nuclei and to melt. Scientists use magnetic fields to confine the resulting substance, which is no longer a gas but a plasma. The "burning plasma", as it is called, is confined in a toroidal shaped apparatus: the tokamak, Russian acronym that translates as "toroidal chamber with magnetic coils".
Schuster, a nuclear fusion Expert in plasma control, he works on ways to control and stabilize heated plasma.
"We are plasma dynamics," says Schuster, describing the role of researchers like him on the path to achieving nuclear fusion energy. "What we do is try to understand plasma dynamics by proposing equations to model its behavior, especially in response to different types of actuators. But we do not stop there. We want to change the actuation to create the dynamics we want. We want the control and stability of the plasma in combustion.
Recent work by members of the Schuster-led Lehigh Plasma Control Laboratory will be presented this week at the 27th International Atomic Energy Agency (IAEA) Mergers Conference in Gandhinagar, India. Their first book, titled "Real-Time Optimization Based on a Physical Model for Developing DIII-D Equilibrium Scenarios", discusses recent experimental results that demonstrate the effectiveness of the DIII-D equilibrium scenarios. a real-time model-based optimization scheme to: systematically perform the desired advanced scenarios at predefined times. The work was done at the DIII-D national smelter, housed at General Atomics, a private technology company located in San Diego, California.
According to Schuster, the results suggest that model-based, control-oriented planning, real-time optimization can play a crucial role in exploring the stability limits of advanced steady-state scenarios.
Their second book, entitled "Robust Regulation of Burns in ITER under Variations in Deuterium-Tritium Concentration in Supply Lines", focuses on how to control the fusion power of a burning plasma when variations occur. measurable deuterium-tritium concentrations in the supply line are present
In this work, the modulation of the coil current in the tank is included in the control scheme, and used in conjunction with the auxiliary power modulation, the modulation of fuel flow and impurity injection to design a non-linear combustion controller robust to deuterium-tritium concentration variations
This controller addresses one of the most fundamental control problems flammable plasma tokamaks, ie regulating the temperature and density of the plasma to produce a determined amount of fusion power while avoiding possible thermal instabilities. A nonlinear simulation study is used to illustrate controller performance in a similar ITER scenario in which unknown variations in deuterium-tritium concentration in supply lines are simulated.
Schuster and his team participate in several national and international collaborations. and regularly conduct experiments on a number of tokamaks around the world. These include DIII-D at General Atomics, where one of his doctoral students and a postdoctoral researcher are stationed permanently; NSTX-U at the Princeton Plasma Physics Laboratory in Princeton, New Jersey, where one of his former PhD students is playing a leading role in plasma control; EST in China; KSTAR in South Korea; and ITER in France.
Schuster, a postdoctoral researcher and four of his PhD students. Students will attend the 60th Annual Meeting of the APS Plasma Physics Division in Portland, Oregon, in early November, where they will present the work resulting from these collaborations.
Schuster Named ITER Scientific Fellow
The International Thermonuclear Experimental Reactor (1965) ITER) is a nuclear fusion tokamak built in the South of France as a result of an unprecedented cooperative effort led by the governments around the world. This global collaboration aims to "build the world's largest tokamak, a magnetic fusion device designed to prove the feasibility of fusion as a large-scale, carbon-free energy source, based on the same principle." of the power of our Sun. and stars. "The ITER project is a collaboration of 35 countries, led by ITER members: China, the European Union, India, Japan, Korea, Russia and the United States .
Schuster, currently head of the Burning Plasma Organization (BPO) in the United States, recently joined the prestigious ITER Scientist Fellows Network, designed to strengthen the participation of the fusion community as ITER prepares for its operational phase. Members of the ITER Fellows Science Network work closely with ITER to solve key research and development issues.
The US Department of Energy has also appointed Schuster as a member of the ITER Thematic Group on Integrated Operational Scenarios within ITPA: International Tokamak Physics Activity (ITPA). The objective of the Integrated Operating Scenarios thematic group is to contribute to the establishment of operational scenarios for combustion plasma experiments, in particular candidate scenarios in ITER.
"Currently, nuclear fusion reactors do not produce energy," says Schuster. "The experiments conducted on tokamaks around the world are focused on the study of plasma physics."
ITER aims to be the first tokamak to produce enough net energy via nuclear fusion for the reaction can last a long time. – and become a reliable source of energy. According to Schuster, the goal is to produce ten times more energy than that injected into the tokamak.
Although researchers have been striving to realize the promises of nuclear fusion for more than sixty years, Schuster thinks they may be closer. The first ITER plasma is planned for 2025.
"Unlike fossil fuels, nuclear fusion does not produce air pollution or greenhouse gases," says Schuster. "Unlike nuclear fission, nuclear fusion poses no risk of nuclear accident, nuclear weapons material generation and low-level radioactive waste."
In other words, the work that Schuster and his colleagues are doing at ITER and other facilities could help us move closer to a future without carbon or combustion, where the energy needs are satisfied by an almost unlimited source – like the sun.
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