Starting Fluid for Laser Fusion

Physics 9, s133
A laser-based fusion experiment demonstrates that liquid fuel capsules could rectify problems encountered with ice-based fuel capsules.
Don Jedlovec/Lawrence Livermore National Laboratory

The strategy of inertial confinement fusion (ICF) is to use high-power lasers to rapidly heat and compress a hydrogen fuel capsule. The fuel is typically frozen, but new work suggests that a liquid state could be more successful at reaching fusion conditions. The experiments at the National Ignition Facility (NIF) in California achieve fusion temperatures with a liquid mixture of heavy hydrogen as starting material.

Nuclear fusion—obtained through inertial confinement or other techniques—could provide the world with a clean and abundant energy supply. In the case of ICF, hundreds of high-power lasers produce x rays that strike a hollow fuel capsule from all sides, causing the fuel to implode. If the compression is high enough in the center, the fuel nuclei will fuse together in a self-sustaining reaction.

During its initial campaign between 2009 and 2012, NIF utilized capsules containing an ice layer of heavy hydrogen. These experiments produced fusion but not at a self-sustaining rate, partly because asymmetry in the x-ray illumination prevented the high fuel compression that is needed. Rick Olson from Los Alamos National Laboratory, New Mexico, and his colleagues have opted for a liquid layer because it should require less compression than ice. To test this concept, the team used a special foam that absorbs the liquid fuel into a spherically symmetric layer along the capsule wall. When exposed to NIF’s lasers at reduced power, the imploding capsule reached temperatures sufficient to trigger fusion, as evident from a yield of neutrons comparable to ice-based experiments. Further work will test whether this liquid approach can achieve self-sustaining reactions at higher laser power.

This research is published in Physical Review Letters.

–Michael Schirber

Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.

Subject Areas

Energy ResearchNuclear PhysicsPlasma PhysicsOptics

Related Articles

Probing Majorana Neutrinos
Particles and Fields

Probing Majorana Neutrinos

Detecting neutrinoless double-beta decay would confirm that the neutrino is its own antiparticle. Data from the KamLAND-Zen experiment contain no strong evidence of such events, constraining neutrino properties. Read More »

Twinkling of a Shrinking Droplet Reveals Hidden Complexity
Atomic and Molecular Physics

Twinkling of a Shrinking Droplet Reveals Hidden Complexity

Captivating patterns found in the light scattered by an evaporating water droplet could be used to infer the properties of the droplet as it shrinks. Read More »

Air Waveguide from “Donut” Laser Beams

Air Waveguide from “Donut” Laser Beams

A waveguide sculpted in air with lasers transmits light over a distance of nearly 50 meters, which is 60 times farther than previous air-waveguide schemes. Read More »

More Articles