Electron-positron plasmas are a prominent feature of the high energy Universe. In the relativistic winds from pulsars and black holes it is thought that non-linear quantum electrodynamics (QED) processes cause electromagnetic energy to cascade into an e-e+ plasma. We show that next-generation 10PW lasers, available in the next few years, will generate such a high density of pairs that they create a micro-laboratory for the first experimental study of a similarly generated e-e+ plasma. In the first simulations of a 10PW laser striking a solid we demonstrate the production of a pure electron-positron plasma of density 10²⁶m^-3. This is seven orders of magnitude denser than currently achievable in the laboratory and is comparable to the critical density for commonly used lasers, marking a step change to collective e-e+ plasma behaviour. Furthermore, a new ultraefficient laser-absorption mechanism converts 35% of the laser energy to a burst of gamma-rays of intensity 10²²Wcm^-2, potentially the most intense gamma-ray source available in the laboratory. This absorption results in a strong feedback between both pair and gamma-ray production and classical plasma physics leading to a new physical regime of QED-plasma physics. In this new regime the standard particle-in-cell (PIC) simulation approach, which has been the dominant kinetic simulation tool in plasma physics for 50 years, is inadequate. We have developed a new approach (QED-PIC) which will provide a powerful new modelling tool essential to the future advancement of the field of high intensity laser-plasma interactions.

Date Published: 7 May 2013
PDF: 6 pages
Proc. SPIE 8780, High-Power, High-Energy, and High-Intensity Laser Technology; and Research Using Extreme Light: Entering New Frontiers with Petawatt-Class Lasers, 87801J (7 May 2013); doi: 10.1117/12.2016378

Published in SPIE Proceedings Vol. 8780:
High-Power, High-Energy, and High-Intensity Laser Technology; and Research Using Extreme Light: Entering New Frontiers with Petawatt-Class Lasers
Georg Korn; Joachim Hein; Luis Oliveira Silva, Editor(s)