Biomedical subjects

R S Craxton

Publications and source records attributed to R S Craxton.

3 recordsLinked to original sources

PubMed2005

The saturn target for polar direct drive on the national ignition facility.

A new target design concept is proposed for direct-drive implosions while the National Ignition Facility is in its initial, indirect-drive configuration. It differs from earlier "polar-direct-drive" designs by adding a low-Z ring around the capsule equator. Refraction in the plasma formed around this ring permits time-dependent tuning of the capsule drive uniformity. An optimized simulation shows an implosion-velocity nonuniformity at the end of the laser pulse of approximately 1% rms for a cryogenic deuterium-tritium shell, enhancing the prospects for an early direct-drive ignition demonstration on the National Ignition Facility.

Journal Article↗

PubMed2003

Multibeam effects on fast-electron generation from two-plasmon-decay instability.

Experiments with multiple laser beams have been carried out in both spherical and planar geometry to study two-plasmon-decay instability, the predominant source of suprathermal electrons in direct-drive inertial confinement fusion experiments. These electrons are observed using the hard x rays generated through electron-target interactions. The experiments show for the first time that the total overlapped intensity governs the scaling of the suprathermal-electron generation regardless of the number of overlapped beams, in contrast to conventional theories that are based on the single-beam approximation.

Journal Article↗

PubMed2002

Multibeam stimulated brillouin scattering from hot, solid-target plasmas.

We report on multibeam, laser-plasma interaction experiments in plasmas relevant to future direct-drive-ignition experiments. Six interaction beams are incident on preformed plasmas containing critical density. Stimulated Brillouin scattering (SBS) shows strong evidence of electromagnetic wave seeding of side- and backscattering. The data are also consistent with shared ion waves driven by the six symmetrically arranged interaction beams. Early SBS quenching is observed and attributed to the hydrodynamics of the plasma.

Journal Article↗