A major upgrade to the DIII-D tokamak fusion reactor operated by General Atomics in San Diego will enable it to develop fusion plasmas that can burn indefinitely.
This is a design drawing showing bus-sized beam injector tilted upward relative to the DIII-D tokamak chamber on the left. Credit: Richard J. Buttery and M.R. Wade, General Atomics
Researchers installed a movable, 30-ton particle-beam heating system that drives electric current over a broad cross section of the magnetically confined plasma inside the reactor's vacuum vessel. Precise aiming of this beamline allows scientists to vary the spatial distribution of the plasma current to maintain optimal conditions for sustaining the high temperature plasmas needed for fusion energy production.
"The ability to systematically adjust the aiming of such a particle beam to control the shape of the current profile is unique to DIII-D among the world's tokamak experi-ments," says Dr. Mickey Wade, Director of Experimental Science for the project. "It provides a timely opportunity for testing and improving our understanding of how internal current and pressure profiles will interact as future burning plasma experiments such as ITER approach steady-state conditions."
The capability to tailor the shape of the current profile is important for maximizing the energy content of the plasma while minimizing the power needed to maintain the large toroidal current that's key to achieving magnetic confinement. Using the beam to broaden the distribution of current across the plasma strengthens the magnetic field structure to support higher plasma pressures. This, in turn, leads to a self-driven "bootstrap" current* which effectively multiplies the original current drive, reducing the need for other external current sources. The will allow the DIII-D team to study the physics of fully self-sustaining plasmas to guide design and operation of future fusion experiments such as the ITER tokamak now under construction in France.
"The project was an enormous challenge, tilting a 30 ton high voltage beam system so that it can be injected at different angles into the plasma with millimeter accuracy," said Tim Scoville, Neutral Beam Systems Manager. "The beam system is nearly as large as the tokamak!"
Physics studies with the newly modified beam have begun, and the system has already been used to make a broader current profile than was previously possible.
"This represents a major step in DIII-D's capability for developing advanced 'steady state' fusion plasmas," said David Hill, DIII-D Deputy Program Director.
The 12 month, $7 million upgrade was completed on time, with the new system commissioned during the latest DIII D cam¬paign. The particle beam upgrade forms part of a larger package of developments underway at the facility, with increases in microwave electron heating to access more burning plasma relevant regimes, and new tools being implemented to develop materials and explore how to handle the hot plasma exhaust.
This work supported by U.S. Department of Energy under DE-FC02-04ER54698.
Saralyn Stewart | EurekAlert!
Unconventional superconductor may be used to create quantum computers of the future
19.02.2018 | Chalmers University of Technology
Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
19.02.2018 | Materials Sciences
19.02.2018 | Materials Sciences
19.02.2018 | Life Sciences