Rapid fabrication and characterization of sine wave targets

The effect of surface perturbations on Inertial Confinement Fusion target performance is currently being researched at Los Alamos National Laboratory (LANL). These perturbations can cause hydrodynamic instabilities which in turn reduce the targets` yield. To systematically measure the growth of these instabilities requires targets to be produced which have perturbations of a known amplitude and spatial frequency. The authors have recently assembled hardware onto one of their diamond turning lathes which enables them to machine and measure these sine waves in about 15 minutes. This is a significant reduction in time from the two and one half hours required by the previous method. This paper discusses the hardware, how it works, and how well the system is working for them to produce these targets

Translations of new public management: a decentred approach to school governance in four OECD countries

Despite the prevalence of corporate and performative models of school governance within and across different education systems, there are various cases of uneven, hybrid expressions of New Public Management (NPM) that reveal the contingency of global patterns of rule. Adopting a ‘decentred approach’ to governance (Bevir, M. 2010. “Rethinking Governmentality: Towards Genealogies of Governance.” European Journal of Social Theory 13 (4): 423–441), this paper compares the development of NPM in four OECD countries: Australia, England, Spain, and Switzerland. A focus of the paper is how certain policy instruments are created and sustained within highly differentiated geo-political settings and through different multi-scalar actors and authorities yet modified to reflect established traditions and practices

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Micromachining of inertial confinement fusion targets

Many experiments conducted on today`s largest inertial confinement fusion drive lasers require target components with sub-millimeter dimensions, precisions of a micron or less and surface finishes measured in nanometers. For metal and plastic, techniques using direct machining with diamond tools have been developed that yield the desired parts. New techniques that will be discussed include the quick-flip locator, a magnetically held kinematic mount that has allowed the direct machining of millimeter-sized beryllium hemishells whose inside and outside surface are concentric to within 0.25 micron, and an electronic version of a tracer lathe which has produced precise azimuthal variations of less than a micron

Current progress in NIF target concepts

Target concepts for the National Ignition Facility (NIF) require progress in the art and science of target fabrication. Three distinct issues are addressed: beryllium fuel capsules, foam-buffered direct drive, and high-density gas-filled hohlraums. In all cases experiments on the existing Nova laser at LLNL are either in progress or planned for the near future to test the various concepts. Consequently, target fabrication must be able to deliver targets appropriate for each