June 23, 2015

Lawrence Livermore able to scale antimatter production with more powerful lasers

Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such as black holes and gamma-ray bursts.

The current lasers are at 500-1000 joules.
The favorable scaling of electron-positron pairs with laser energy obtained in these experiments suggests that, at a laser intensity and pulse duration comparable to what is available, near-future 10-kilojoule-class lasers would provide 100 times higher antimatter yield.

This would be about 100 trillion positron pairs or 10^14.

There are many interesting applications that start becoming feasible if you can regularly and quickly generate 10^19 positrons in less than 1000 seconds.

A 1 gigawatt antimatter ignited nuclear fusion generator becomes possible. 10^19 positrons can be used to trigger deuterium tritium fusion.

Laser production of copious positrons from the vacuum occurs when the laser intensity gets higher than 10^23 Watts per cm squared.

Physical Review Letters - Scaling the Yield of Laser-Driven Electron-Positron Jets to Laboratory Astrophysical Applications

Abstract

Researchers report new experimental results obtained on three different laser facilities that show directed laser-driven relativistic electron-positron jets with up to 30 times larger yields than previously obtained and a quadratic (∼E2L) dependence of the positron yield on the laser energy. This favorable scaling stems from a combination of higher energy electrons due to increased laser intensity and the recirculation of MeV electrons in the mm-thick target. Based on this scaling, first principles simulations predict the possibility of using such electron-positron jets, produced at upcoming high-energy laser facilities, to probe the physics of relativistic collisionless shocks in the laboratory.

Dependence of the measured positron yield on the laser energy, EL, obtained at three different laser facilities: Omega EP, Orion, and Titan. The upper group is from shots with 1 ps laser pulse: (brown) triangles Titan and (green) diamonds Orion. The lower group is obtained with 10 ps laser pulse: (blue) squares Titan and (red) circles Omega EP.







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