Synopsis

Nuclear Reactions in Lab Plasma

Physics 6, s113
Using powerful laser pulses, researchers are able to study nuclear reactions in a plasma without the screening effect of bound electrons.
Courtesy M. Barbui/Texas A&M University

Many low-energy nuclear reactions in astrophysics occur in plasmas, in which the nuclei are free of electrons. By contrast, most nuclear experiments involve neutral targets, whose bound electrons produce a “screening effect.” A new technique uses lasers to remove these unwanted electrons so that low-energy nuclear reactions can be studied directly in laboratory plasma. The authors demonstrate their approach in Physical Review Letters on the deuterium/helium-3 interaction that helped synthesize elements in the early Universe and could potentially be used to power a future nuclear fusion reactor.

In a typical nuclear reaction experiment, an ion beam is directed at a target containing neutral atoms. The bound electrons provide a screen that reduces the Coulomb repulsion between the positive nuclei. Therefore, laboratory measurements tend to predict higher reaction rates than would be expected between ionized nuclei. To obtain astrophysically relevant parameters, researchers try to correct their data by estimating the screening effect of the bound electrons.

Marina Barbui from Texas A&M University, College Station, and her colleagues have instead found a way to directly observe a reaction inside a plasma. In particular, they studied the interaction between deuterium and helium-3 that leads to helium-4 and a proton. The researchers used a high-powered petawatt laser to explode apart deuterium molecular clusters, producing low-energy deuterium ions. Some of the deuterium ions collided with slow-moving helium-3 nuclei, which were also nearly completely ionized by the laser pulse. The team measured the effective rate of helium-4 production inside their plasma and found it consistent with other measurements. The group plans to use their method to study other low-energy reactions, such as those involved in the CNO cycle of stars. – Michael Schirber


Subject Areas

AstrophysicsNuclear Physics

Related Articles

An Elusive Black Hole Comes into View
Astrophysics

An Elusive Black Hole Comes into View

Observations of seven fast-moving stars at the center of a dense star cluster in the Milky Way reveal the presence of an intermediate-mass black hole, perhaps the most puzzling class of these dark objects. Read More »

Dark Matter Could Bring Black Holes Together
Astrophysics

Dark Matter Could Bring Black Holes Together

Dark matter that interacts with itself could extract significant momentum from a binary supermassive black hole system, causing the black holes to merge. Read More »

Nuclear Decay Detected in the Recoil of a Levitating Bead
Nuclear Physics

Nuclear Decay Detected in the Recoil of a Levitating Bead

A levitating microparticle is observed to recoil when a nucleus embedded in the particle decays—opening the door to future searches of invisible decay products. Read More »

More Articles