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

Pneumo-tronic Perturbator for the Study of Human Postural Responses

Abstract Author keywords Indexed keywords SciVal Topics Metrics Abstract This paper describes the design and operational principles of a device that imparts a well-controlled mechanical force or impulse, a so-called perturbation, to a pre-selected point on the surface of the human body. This perturbator will be integrated within a system aimed at measuring and evaluating human postural reaction in a clinically meaningful way. The ease of use and versatility of the device renders it suitable for manual operation but it can also be integrated in a robotized system. The hardware, control law and characterization of the perturbator are presented. Preliminary results indicate that the device is able to generate repeatable perturbations with characteristics appropriate to the intended application. Further improvements are discussed and proposed

Radio frequency spectral characterization and model parameters extraction of high Q optical resonators

International audienceA microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor