(Photo by Elle
Starkman/PPPL; Lisa Petrillo/GA for Carlos Paz-Soldan and Raffi Nazikian)
From top left:
1.Magnetic island geometry revealing the mechanism for the density limit.
(Reprinted with
permission from Phys. Plasmas 22, 022514 2015);
2.Carlos
Paz-Soldan and Raffi Nazikian advanced understanding of the control of heat
bursts;
3.interior of the
NSTX-U showing the completed center stack; 4.W7-X stellarator in Greifswald,
Germany;
5.solar flare at
the peak of the cycle in October, 2014, with no observed eruptions. Background:
umbrella view of
the interior of the NSTX-U.
(January 13, 2016) From
launching the most powerful spherical tokamak on Earth to discovering a
mechanism that halts solar eruptions, scientists at the U.S. Department of
Energy’s Princeton Plasma Physics Laboratory advanced the boundaries of clean
energy and plasma science research in 2015. Here, in no particular order, are
our picks for the Top-5 developments of the year:
1.Starting up the
National Spherical Torus Experiment-Upgrade (NSTX-U)
PPPL completed construction of the NSTX-U (link is
external), the Laboratory’s flagship fusion facility, doubling its heating and
magnetic power and making it the most powerful spherical tokamak in the world.
The machine is shaped like a cored apple, unlike conventional donut-shaped
fusion facilities, and creates high plasma pressure with relatively low magnetic
fields — a highly cost-effective feature since magnetic fields are expensive to
produce. The upgrade creates a flexible research platform that will enable
physicists to directly address some of fusion’s most outstanding puzzles.
2. Discovering a
mechanism that halts solar eruptions
Solar eruptions are massive explosions of plasma and
radiation from the sun that can be deadly for space travelers and can disrupt
cell phone service and other crucial functions when they collide with the
magnetic field that surrounds Earth. Researchers working on the Magnetic
Reconnection Experiment (MRX), the world’s premier device for studying the
convergence and separation of magnetic fields in plasma, have discovered a
previously unknown mechanism that causes eruptions to fail. The findings could
prove highly valuable to NASA, which is eager to know when an eruption is
coming and when the start of an outburst is just a false alarm.
3. First plasma on
Germany’s Wendelstein 7-X
On December 10, 2015, the Wendelstein 7-X (W7-X) stellarator
produced its first plasma after 10 years of construction. PPPL, which leads the
United States’ collaboration in the German project and will conduct research on
it, joined the worldwide celebration of the achievement. The Laboratory
designed and delivered five barn-door size magnetic coils, together with power
supplies, that will help shape the plasma during W7-X experiments. The Lab also
designed and installed an X-ray diagnostic system that will collect vital data
from the plasma in the machine. Stellarators are fusion facilities that confine
plasma in twisty — or 3D — magnetic fields, compared with the symmetrical — or
2D — fields that tokamaks produce.