Increased efficiency of short-pulse laser-generated proton beams from novel flat-top cone targets
- 1 May 2008
- journal article
- research article
- Published by AIP Publishing in Physics of Plasmas
- Vol. 15 (5), 056709
- https://doi.org/10.1063/1.2918125
Abstract
Ion-driven fast ignition (IFI) may have significant advantages over electron-driven FI due to the potentially large reduction in the amount of energy required for the ignition beam and the laser driver. Recent experiments at the Los Alamos National Laboratory’s Trident facility employing novel Au flat-top cone targets have produced a fourfold increase in laser-energy to ion-energy efficiency, a 13-fold increase in the number of ions above , and a few times increase in the maximum ion energy compared to Au flat-foil targets. Compared to recently published scaling laws, these gains are even greater. If the efficiency scales with intensity in accordance to flat-foil scaling, then, with little modification, these targets can be used to generate the pulse of ions needed to ignite thermonuclear fusion in the fast ignitor scheme. A proton energy of at least was measured from the flat-top cone targets, and particle-in-cell (PIC) simulations show that the maximum cutoff energy may be as high as at modest intensity of with in . Simulations indicate that the observed energy and efficiency increase can be attributed to the cone target’s ability to guide laser light into the neck to produce hot electrons and transport these electrons to the flat-top of the cone where they can be heated to much higher temperatures, creating a hotter, denser sheath. The PIC simulations also elucidate the critical parameters for obtaining superior proton acceleration such as the dependence on laser contrast/plasma prefill, as well as longitudinal and transverse laser pointing, and cone geometry. These novel cones have the potential to revolutionize inertial confinement fusion target design and fabrication via their ability to be mass produced. In addition, they could have an impact on the general physics community studying basic electron and radiation transport phenomena or as better sources of particle beams to study equations of state and warm dense matter, or for hadron therapy, as new radioisotope generators, or for compact proton radiography sources.
Keywords
This publication has 39 references indexed in Scilit:
- Reentrant cone angle dependence of the energetic electron slope temperature in high-intensity laser-plasma interactionsPhysics of Plasmas, 2007
- Laser prepulse dependency of proton-energy distributions in ultraintense laser-foil interactions with an online time-of-flight techniquePhysics of Plasmas, 2007
- Editorial from the Editor in Chief: The Start of a New YearLaser and Particle Beams, 2007
- Laser accelerated ions in ICF research prospects and experimentsPlasma Physics and Controlled Fusion, 2005
- Laser-ablation treatment of short-pulse laser targets: Toward an experimental program on energetic-ion interactions with dense plasmasLaser and Particle Beams, 2005
- Plasma devices to guide and collimate a high density of MeV electronsNature, 2004
- High power laser production of short-lived isotopes for positron emission tomographyJournal of Physics D: Applied Physics, 2004
- High-energy ion generation by short laser pulsesPlasma Physics Reports, 2004
- Effect of target heating on ion-induced reactions in high-intensity laser–plasma interactionsApplied Physics Letters, 2003
- Proton spectra from ultraintense laser–plasma interaction with thin foils: Experiments, theory, and simulationPhysics of Plasmas, 2003