General Atomics Scientists Achieve Key Requirement for Economic Fusion Energy
2024年6月18日 - 10:15PM
A team led by scientists from General Atomics (GA) has
demonstrated, for the first time, an operational approach that is
key to many tokamak-based fusion power plant (FPP) designs aiming
to generate economically attractive electricity.
The experiments at the DIII-D National Fusion Facility achieved
a combination of high density and high confinement of the fuel that
had never previously been achieved simultaneously. The results were
published in an article in Nature in late April.
“This is a landmark result,” said Dr. Siye Ding, the GA
scientist who led the team. “For the first time, we’ve been
able to demonstrate a model operational scenario that could be
employed by fusion power plants seeking to achieve economically
viable electricity generation.”
Advancing the Tokamak Approach to Fusion
Energy
The tokamak approach is considered by most experts to be the
most mature and promising method of generating fusion energy.
Tokamak-based FPPs will use powerful magnetic fields to confine a
fuel gas composed of hydrogen isotopes in a high-temperature state
known as a plasma. Delivering economically attractive fusion energy
will require these tokamaks to maintain very high density and
plasma confinement better than a current approach known as
“high-confinement mode” (H-mode).
The DIII-D National Fusion Facility is the largest research
tokamak in the United States. It is operated by GA on behalf of the
DOE’s Office of Science as a user facility for the U.S. fusion
research program. As a world-class laboratory, over 700 researchers
from more than 100 domestic and international institutions use
DIII-D to explore a wide range of topics from fundamental plasma
science to FPP operations.
Scientists have been able to create fusion in tokamaks for
decades. However, to produce economically attractive electricity,
FPPs will need to perform at substantially higher efficiencies than
current tokamaks can manage. Two key elements of this are the
confinement quality and the density of the plasma that a tokamak is
able to maintain during operation.
Confinement quality is best understood as the ability of a
tokamak to contain the energy of the fuel at specific conditions
long enough to generate a sufficient level of fusion power. High
confinement quality requires a low degree of turbulence in the
plasma because turbulence allows heat to escape the magnetic
fields. Confinement quality is a critical element in the
cost-effectiveness of a FPP, because it has a direct impact on the
necessary size of the tokamak and other systems of the plant.
H-mode plasmas are viewed as the most promising approach for
tokamaks and have been achieved for many years. However, generating
enough fusion power to be economically viable requires that the
plasma be confined at densities above an empirically defined level,
known as the Greenwald Limit.
Breaking Through the “Greenwald Limit”
Previous attempts to reach this point with H-mode plasmas have
struggled with high turbulence in the plasma core and instabilities
at the edge that disrupt confinement and can potentially damage the
tokamak, especially at FPP scale. The need to simultaneously
maintain a stable edge and a high-density core – something fusion
scientists refer to as “core-edge integration” – is one of the key
challenges for fusion energy.
For several years, work at DIII-D has explored methods to
suppress turbulence and instabilities while achieving high density
and confinement quality. During an experimental campaign in 2022,
researchers developed an approach in which the plasma can stabilize
itself into a magnetic configuration that achieves both
conditions.
This approach exploits a configuration known as “high-poloidal
beta” to create plasmas with densities that increase rapidly from
the edge to the core. The steep density profile helps suppress core
turbulence and enables the high density in the center of the plasma
that is necessary for fusion power.
The experiments on DIII-D achieved densities 20 percent above
the Greenwald Limit and confinement quality 50 percent better than
standard H-mode – the first time any fusion plasma at any facility
has reached these heights simultaneously. They also exhibited a
stable plasma edge, pointing to a potential solution to the
core-edge integration challenge.
“This work supports critical requirements in fusion reactor
designs all over the world,” Dr. Ding said.
“The physics we’ve demonstrated with these experiments can be
extrapolated to full-scale FPPs via integrated modeling, indicating
a path toward economic fusion energy.”
Accelerating Clean Fusion Energy
Fusion is the process that powers the stars, and it offers the
potential for nearly limitless clean, safe, and carbon-free
electricity. As a sustainable, high-output, and dispatchable energy
source, fusion would put the U.S. on a path to energy independence
and transform the global energy landscape.
As demand for energy grows, fusion is one of the best options
for meeting the world’s clean energy needs around the clock while
reducing emissions and growing the economy. Developing commercially
scalable fusion would ensure energy security while meeting
important environmental goals and delivering trillions of dollars
in economic benefits.
“These results are really exciting and demonstrate a real
roadmap for operating a tokamak in a way that is consistent with
the needs of a fusion pilot plant,” added
Dr. Wayne Solomon, Vice President of Magnetic Fusion Energy
at General Atomics. “The next step is to build on the
successes of these experiments by continuing to close remaining
scientific gaps as we look ahead to bringing fusion energy to the
grid.”
About General Atomics: Since the dawn of the atomic age,
General Atomics innovations have advanced the state of the art
across the full spectrum of science and technology – from nuclear
energy and defense to medicine and high-performance computing.
Behind a talented global team of scientists, engineers, and
professionals, GA’s unique experience and capabilities continue to
deliver safe, sustainable, economical, and innovative solutions to
meet growing global demands.
- General Atomics Scientists Achieve Key Requirement for Economic
Fusion Energy
Evan Polisar
General Atomics
619-538-2700
gregory.s.cunningham@ga.com