Laser-Driven Collisionless Shocks in the Large Plasma Device

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

This award is made in response to a proposal submitted to and reviewed under the NSF/DoE Partnership in Basic Plasma Science and Engineering joint solicitation NSF 08-589. This award provides funds to support undergraduate participation in the overall research effort, which is being funded separately by DoE. The experimental high-energy laser-capability developed during the last two years at the Large Plasmas Device (LPD) will be used to create collisionless shocks in a controlled laboratory setting and study their structure, dissipation mechanisms, and effect on the particle velocity distribution in great detail. In addition, the dynamics of large diamagnetic cavities in the presence of an ambient plasma,will be studied, as well as their coupling to large amplitude shear Alfvén waves. Recent experiments with an energetic laser-produced plasma have already compressed the external magnetic field at the edge of a 20 cm large diamagnetic cavity by more than 50%. Ongoing upgrades to both the laser driver and the plasma source will extend the experiments to time-scales of the order of the ion-gyroperiod, providing enough time for a shock to form. Collisionless shocks are ubiquitous in space and influence energy transport and the particle distribution throughout the cosmos. These shocks are formed, for example, in supernova remnants, coronal mass ejections, or planetary bow-shocks, and are a source of cosmic rays. Unlike a hydrodynamic shock, which dissipates its energy through binary collisions, a collisionless shock forms in a tenuous plasma where the energy transfer proceeds through collective electromagnetic effects. The experiments will be modeled using a parallel, three-dimensional hybrid plasma code. The broader impacts of this work are that, with the addition of the large ambient plasma, these laser-experiments will fill an important gap that has limited the relevance of previous laser laboratory astrophysics experiments in vacuum. This project will also help to establish laser-laboratory astrophysics as an important area of research. In addition, the synergism between basic plasma science and high-energy density physics will lead to new findings important to a number of scientific disciplines. It is envisioned that a new generation of researchers will be trained who will acquire a solid background in both fields. The additional funding from NSF will permit increased student involvement, in this case specifically an undergraduate student, in this research.