FES Highlights

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November 5, 2020
Density peaking increases with decreasing collisionality (blue squares), with the largest increases linked to changes in electron transport (yellow triangles), not in core fueling (red circles).
DIII-D Scientists Identify New Peaks in Fusion Power
Transport effects raise the density in the plasma core.
September 30, 2020
Composite image of a white dwarf star inside a tiny, gold canister (hohlraum) at the National Ignition Facility. Compression of the material inside the target was measured by time-resolved X-ray radiography.
Shedding Light on Stellar Evolution
Experiments reveal relationship between density of matter & extreme pressure in stellar objects, putting constraints on models of white dwarf stars.
September 4, 2020
An example from the DOE DIII-D facility of the perturbation to the edge region of a tokamak’s magnetic field due to resonant magnetic fields.
An Innovation for Fusion Device Walls May Have Unexpected Benefits for the Core
A technique that suppresses damaging instabilities also improves the exhaust of helium ‘ash’ in the DIII-D tokamak, improving conditions for fusion.
September 2, 2020
The AI DefectSegNet models outperform human experts at perceiving radiation defects in advanced microscopy images, helping to design materials for nuclear reactors.
AI Helps Scientists Quantify Irradiation Effects
Novel Convolutional Neural Network combined with advanced microscopy offers a path to automated and reliable radiation defect analysis.
August 18, 2020
The novel method focuses laser light by sending an optical pulse (yellow lines) to the right to reflect from a radial echelon (rightmost element); the pulse then reflects from an axiparabola (leftmost element) to control when each ring comes to focus.
Controlling Light to Accelerate Electrons in Just Meters
A novel paradigm for pushing energy in a particle accelerator method could dramatically shrink future accelerators.
July 31, 2020
Laser-driven experiments and numerical simulations now show that small-scale turbulence produced at the shock can be key in the initial acceleration of electrons from supernovas.
Lab-Created Shock Waves Mimic Supernova Particle Accelerators
New laser-driven experiments and numerical simulations reveal an electron acceleration mechanism relevant to young supernova shock waves.
July 15, 2020
This image shows an instability (the ring-like structure at the center) caused by a runaway electron beam inside the DIII-D tokamak. These instabilities suggest methods for controlling these damaging electron beams.
Scientists Solve Key Challenge for Controlling “Runaway” Electrons in Fusion Plasmas
Discovery could help control potentially damaging bursts during plasma disruptions, another step toward fusion power production.
April 14, 2020
Researchers developed and tested a new top-launch configuration for injecting microwaves into the plasma in the DIII-D tokamak.
Moving on Up, to the Top for Fusion Power
New approach doubles the current driven by microwave heating at the DIII-D National Fusion Facility.
March 27, 2020
The radial wind created in the plasma stretches the magnet field out radially forming a current sheet and spiraling magnetic field. 3-axis Hall probe measurements are shown as an axisymmetric 3D field-line rendering.
Parker Spiral Created in the Laboratory for the First Time Ever
Scientists created the Parker spiral – the spiral magnetic field structure of the Sun due to its rotation – in the lab.
March 18, 2020
Simulations predict that when magnetic bubbles form at the edge of the plasma and allow some of the hot plasma to escape, they suppress intense bursts of heat and particles. The image shows the magnetic field structure near the plasma surface.
Magnetic Ripples Calm the Surface of Fusion Plasmas
3D magnetic fields can help control the plasma edge to prevent damaging bursts of heat and particles from fusion plasma.
March 18, 2020
By shooting pellets of frozen hydrogen into fusion plasma in a tokamak, scientists at the DIII-D National Fusion Facility have been able to control instabilities in the magnetic field that holds plasma together.
Island Retreat: Pellets Help Remove Magnetic Island Instabilities
Injecting pellets into fusion plasma helps repair tears in fusion reactors’ magnetic fields, improving prospects for fusion energy.
February 5, 2020
Plasma edge temperature profile showing staircase formation and higher core temperature during bursting mode activity (blue) compared to the quiescent case where the staircase does not form (red).
Climbing the Staircase to Fusion
Forming a staircase in the edge of the plasmas can boost the performance of a fusion reactor.
December 17, 2019
Image of measurements of the intensity of the line radiation emitted by tungsten atoms eroding from the region of highest heat and plasma flux on the tokamak wall, known as the divertor.
Unraveling how Tungsten Armor Erodes in Tokamak Walls
New high-resolution measurements of tokamaks’ tungsten walls may provide insight into how to better protect the armor material.
September 18, 2019
Atomic scale views of irradiation-induced defects in titanium diboride after irradiation at ~200 degrees Celsius.
Investigating Materials that Can Go the Distance in Fusion Reactors
A test of titanium diboride opens the door to a potential new class of materials for fusion reactor applications.
June 14, 2019
Cross sections of pressure profiles in two different tokamak plasma configurations (the center of the tokamak doughnut is to the left of these). The discharges have high pressure in the core (yellow) that decreases to low pressure (blue) at the edge.
Flipping the Script with Reverse D-Shaped Plasmas
Mirrored D shape demonstrates surprisingly high pressures in a tokamak, indicating a shape change may be in order for next-generation fusion reactors.
June 14, 2019
A boron-filled diamond shell (left). The process (right, a): (1) shell pellet hitting the boundary of the plasma, (2) continuing through the surface, and (3) ablating and releasing boron dust. (b) Expanded view, highlighting shell and dust.
A Trojan Horse for Fusion Disruptions
Thin-walled diamond shells carry payloads of boron dust; the dust mitigates destructive plasma disruptions in fusion confinement systems.
April 22, 2019
Princeton’s Fusion Recurrent Neural Network code uses convolutional & recurrent neural network components to integrate spatial & temporal information for predicting disruptions in tokamak (central structure) plasmas with unprecedented accuracy and speed.
Artificial Intelligence and Deep Learning Accelerate Efforts to Develop Clean, Virtually Limitless Fusion Energy
The Fusion Recurrent Neural Network reliably forecasts disruptive and destructive events in tokamaks.
April 18, 2019
In the regimes where classical theory breaks down for measuring heat flux in plasma, a team determined electron distribution functions — consistent with nonlocal thermal transport — use the measured collective Thomson-scattering spectrum.
Capturing Energy Flow in a Plasma by Measuring Scattered Light
First measurements of heat flux in plasmas experientially sheds light on models relying on classical thermal transport.
February 19, 2019
A team working at the DIII-D National Fusion Facility discovered that external 3-D magnetic fields drive strong distortions in high-pressure plasmas that help suppress bursts of heat in fusion reactors.
Steady as She Goes
Scientists tame damaging edge instabilities in steady-state conditions required in a fusion reactor.
February 19, 2019
Researchers used a novel transverse configuration to compress a silicon target with an optical laser (green). X-ray diffraction patterns are collected in transmission on Cornell–SLAC Pixel Array Detectors.
Silicon and a State of Shock
A novel experimental geometry at the Linac Coherent Light Source reveals how silicon responds to shocks similar to those in a planet's core.
February 19, 2019
A new approach collects light emitted by plasma due to interaction with an injected neutral deuterium beam and transmits the light to spectrometers, by tuning the spectrometers to the rest wavelength of a visible deuterium spectral line.
Not All Ions in Tokamaks Go with the Flow
Spectroscopic measurements reveal that main ions flow much faster than impurities at the edge of fusion-relevant plasmas.
February 17, 2019
Contour plot of a cross-section plane around the magnetic islands (depicted by dashed lines), showing the variation of the electrostatic potential associated with the magnetic island.
New Model Sheds Light on Key Physics of Magnetic Islands that Can Halt Fusion Reactions
Surprisingly, a magnetic island does not necessarily perturb the plasma current in a dangerous way and destroy fusion performance.
February 17, 2019
Rapidly accelerating kink instability (arch shape) of a plasma jet produces an effective gravity that causes “ripples” (seen on bottom of the arch). The ripples choke the jet at which time a burst of 6 kilovolt X-rays is observed.
High-Energy X-Ray Bursts from Low-Energy Plasma
Scientists discover why solar flares produce X-rays; a few electrons avoid collisions and accelerate to produce a microsecond burst.
December 6, 2018
The Biermann Battery Effect: Spontaneous Generation of Magnetic Fields and Their Severing
The Biermann Battery Effect: Spontaneous Generation of Magnetic Fields and Their Severing
Magnetic reconnection occurs when oppositely directed magnetic fields are forced together in plasmas, which are excellent electrical conductors. A
December 6, 2018
Drawn into a Whirlpool: A New Way to Stop Dangerous Fast Electrons in a Fusion Device
Drawn into a Whirlpool: A New Way to Stop Dangerous Fast Electrons in a Fusion Device
Just like when pushing a playground swing, energy is only transferred from the electron beam to the whistler wave when the “pushing”