November 2, 2009
Trident Laser Used To Accelerate Protons To Record Energies
Laser-particle acceleration is expected to contribute to future advances in modern cancer radiotherapy
An international team of physicists at Los Alamos National Laboratory has succeeded in using intense laser light to accelerate protons to energies never before achieved. Using this technique, scientists can now accelerate particles to extremely high velocities that would otherwise only be possible using large accelerator facilities. Physicists around the world are examining laser particle acceleration and laser produced radiation for potential future uses in cancer treatment.
The new record was achieved using specially shaped targets at Trident, the world's highest contrast high-intensity, high-energy laser. The scientists shot high-contrast ultrashort laser pulses lasting approximately 600 femtoseconds (600 quadrillionths of a second) and around 80 Joules directly into the cone-shaped structures, whose flat-top tips are covered with a thin film. The surfaces were created using nanotechnology, and produced by the company Nanolabz.
When the intense laser light collides with the inside of these anvil-like microstructures, electrons are liberated from the material. In contrast to flat-foils, the microstructures act as an electron guide to the tip. The electric field generated can then be used to accelerate the protons to energies that were previously unachievable. X-ray imaging was used as a diagnostic tool to help illustrate and clarify the laser-cone interaction. The precise interactions, however, must still be resolved by the scientists via computer simulations. Next, they will study the cones ability to efficiently convert laser light into high energy protons.
The record measurements will be presented at the annual APS Division of Plasma Physics meeting in November 2009 in Atlanta, GA.
Image Caption: This is an image of the infrared laser (not seen, entering from left-hand side) interacting with a flat target (center), and the associated plasma production from the interaction on the various diagnostic instruments in the chamber. This is a time integrated image over five seconds. Credit: Joe Cowan and Kirk Flippo, LANL
On the Net: