Statistical Survey of Type III Radio Bursts at Long Wavelengths Observed by the Solar TErrestrial RElations Observatory (STEREO)/Waves Instruments: Radio Flux Density Variations with Frequency

We have performed a statistical study of $152$ Type III radio bursts observed by Solar TErrestrial RElations Observatory (STEREO)/Waves between May 2007 and February 2013. We have investigated the flux density between $125$kHz and $16$MHz. Both high- and low-frequency cutoffs have been observed in $60\,$ of events suggesting an important role of propagation. As already reported by previous authors, we observed that the maximum flux density occurs at $1$MHz on both spacecraft. We have developed a simplified analytical model of the flux density as a function of radial distance and compared it to the STEREO/Waves data.Comment: published in Solar Physic

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

Simple target models for ion beam fusion systems studies

Some of the target information required for reactor and systems studies is not readily available. In this paper we attempt to improve this situation by developing simple target models that give estimates of DT fuel mass, the masses of other target constituents, the DT burn fraction, and the fraction of energy in neutrons

Directions for Reactor Target Design Based on the U.S. Heavy Ion Fusion Systems Assessment

We studied areas of major uncertainty in target design using the cost of electricity as our figure of merit. Net electric power from the plant was fixed at 1000 MW to eliminate large effects due to economies of scale. The system is relatively insensitive to target gain. Factors of three changes in gain cause only 8 to 12% changes in electricity cost. An increase in the peak power needed to drive targets poses only a small cost risk, but requires many more beamlets be transported to the target. A shortening of the required ion range causes both cost and beamlet difficulties. A factor of 4 decrease in the required range at a fixed driver energy increases electricity cost by 44% and raises the number of beamlets to 240. Finally, the heavy ion fusion system can accommodate large increases in target costs. To address the major uncertainties, target design should concentrate on the understanding requirements for ion range and peak driver power

Between professional values, social regulations and patient preferences: medical doctors' perceptions of ethical dilemmas.

Background: We present and discuss the results of a Norwegian survey of medical doctors' views on potential ethical dilemmas in professional practice. Methods: The study was conducted in 2015 as a postal questionnaire to a representative sample of 1612 doctors, among which 1261 responded (78%). We provided a list of 41 potential ethical dilemmas and asked whether each was considered a dilemma, and whether the doctor would perform the task, if in a position to do so. Conceptually, dilemmas arise because of tensions between two or more of four doctor roles: the patient’s advocate, a steward of societal interests, a member of a profession, and a private individual. Results: 27 of the potential dilemmas were considered dilemmas by at least 50% of the respondents. For more than half of the dilemmas the anticipated course of action varied substantially within the professional group, with at least 20% choosing a different course than their colleagues, indicating low consensus in the profession. Conclusions: Doctors experience a large range of ethical dilemmas, of which many have been given little attention by academic medical ethics. The less discussed dilemmas are characterized by a low degree of consensus in the profession about how to handle them. There is a need for medical ethicists, medical education, postgraduate courses and clinical ethics support to address common dilemmas in clinical practice. Viewing dilemmas as role conflicts can be a fruitful approach to these discussions

Magnetic bunchers for the generation of high peak current, low emittance electron pulses at medium energy

In this paper, we will outline the various physical constraints and issues for magnetic buncher design. Discussion of achromatic design and dispersion and minimizing rf power will be presented. We will provide generic designs for positive and negative dispersion, and describe the effect of curvature in the energy-phase correlation due to the sinusoidal nature of the rf fields on the output pulse shape. Methods to remove the curvature will be examined. Finally this paper will cover simple nonlinear dispersion which can compensate for the curvature