Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

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.

Field evaluation of a method for estimating gaseous fluxes from area sources using open-path Fourier transform infrared

This paper describes results from the first field experiment designed to evaluate a new approach for quantifying gaseous fugitive emissions of area air pollution sources. The approach combines path-integrated concentration data acquired with any path-integrated optical remote sensing (PI-ORS) technique and computed tomography (CT) technique. In this study, an open-path Fourier transform infrared (OP-FTIR) instrument sampled path-integrated concentrations along five radial beam paths in a vertical plane downwind from the source. A meteorological station collected measurements of wind direction and wind speed. Nitrous oxide (N2O) was released from a controlled area source simulator. The innovative CT technique, which applies the smooth basis function minimization method to the beam data in conjunction with measured wind data, was used to estimate the total flux from the simulated area source. The new approach estimates consistently underestimated the true emission rates in unstable atmospheric conditions and agreed with the true emission rate in neutral atmospheric conditions. This approach is applicable to many types of industrial areas or volume sources, given the use of an adequate PI-ORS system.

Application of standardized quality control procedures to open-path Fourier transform infrared data collected at a concentrated swine production facility

Open-path Fourier transform infrared (OP/FT-IR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gases at a concentrated swine production facility. A total of 2200 OP/FT-IR spectra were acquired along nine different monitoring paths during an 8-day period between January 11 and 22, 1999. Standardized quality control (QC) procedures were applied to the archived OP/FT-IR spectra to verify that the instrument was set up and operating properly during the field study and to identify outliers in the concentration data. These QC procedures included measuring the random baseline noise, the signal strength, and the relative single-beam intensity in selected wavenumber regions; inspecting the archived spectra for wavenumber shifts, changes in resolution, and evidence of detector saturation; and examining time series plots of the target gas concentrations and the uncertainty values reported by the classical least-squares (CLS) analysis. Application of these QC procedures to the archived spectra identified 252 potential outliers. After a careful review of the original spectra, 41 of the 252 suspected outliers were designated as actual outliers. Of the QC criteria used during this study, the uncertainty values reported by the CLS analysis were the most reliable indicators of actual outliers.

Comparison of the particle size distribution of heavy-duty diesel exhaust using a dilution tailpipe sampler and an in-plume sampler during on-road operation

Originally constructed to develop gaseous emission factors for heavy-duty diesel trucks, the U.S. Environmental Protection Agency's (EPA) On-Road Diesel Emissions Characterization Facility has been modified to incorporate particle measurement instrumentation. An electrical low-pressure impactor designed to continuously measure and record size distribution data was used to monitor the particle size distribution of heavy-duty diesel truck exhaust. For this study, which involved a high-mileage (900,000 mi) truck running at full load, samples were collected by two different methods. One sample was obtained directly from the exhaust stack using an adaptation of the University of Minnesota's air-ejector-based mini-dilution sampler. The second sample was pulled from the plume just above the enclosed trailer, at a point approximately 11 m from the exhaust discharge. Typical dilution ratios of about 300:1 were obtained for both the dilution and plume sampling systems. Hundreds of particle size distributions were obtained at each sampling location. These were compared both selectively and cumulatively to evaluate the performance of the dilution system in simulating real-world exhaust plumes. The data show that, in its current residence-time configuration, the dilution system imposes a statistically significant bias toward smaller particles, with substantially more nanoparticles being collected than from the plume sample.

Plasma ammonia and lactate responses using incremental and constant speed exercise tests

Plasma NH3, formed during intense exercise, results principally from the deamination of AMP in muscle. Its formation during exercise may be influenced both by the pool of fibres recruited and by changes in the intracellular environment affecting ADP homeostasis. This study compared incremental and constant speed exercise as possible protocols for the investigation of plasma NH3 accumulation with intense exercise. Six trained Thoroughbred horses, one of which had recently been operated on for recurrent laryngeal neuropathy, undertook a step-wise treadmill test with 1 min incremental steps of 6, 8, 10, 11 and 12 m/s (7.5% incline). Two and 4 weeks later horses performed a constant-speed, maximum-exercise tolerance test at 115% VO2max (7.5% incline). Blood samples from the jugular vein were drawn at 20 s intervals in all 3 tests, for plasma NH3 and lactate. There were marked differences between and within horses in their time dependant lactate and NH3 responses to exercise. Three of the 6 horses studied showed a distinct threshold for onset of plasma NH3 accumulation with incremental exercise. Distinct thresholds for the onset of NH3 accumulation were apparent also in 5 of the 6 horses during exercise at constant rate. The present study demonstrates clearly the practicality of measuring NH3 concentration curves, even during a short incremental step test which has the advantage that other measures relating to cardiovascular and respiratory functions can be measured simultaneously.

ATP loss with exercise in muscle fibres of the gluteus medius of the thoroughbred horse

Muscle ATP loss with exercise has implications both to the causes of fatigue and muscle damage. To study this at the single muscle fibre level, five trained thoroughbred horses performed consecutive 90 second gallops on an inclined treadmill followed by a final gallop to fatigue. Biopsies of the m. gluteus medius were taken at rest, post-exercise and during 24 hour recovery. Blood lactate was 20.0 mmol litre-1 or more, and plasma NH3 300-800 mumol litre-1, following the final gallop. Minimal changes occurred in the plasma markers, CK and AST. ATP loss with exercise was 32.2 (SD 12.2) per cent. Following exercise single fibre ATP contents showed a much broader distribution than at rest, with contents in some close to zero. Following five and 24 hour recovery, however, frequency distribution curves were close to those seen at rest. There was no difference in the ATP contents of types I, IIa and IIb at rest of with exercise or recovery. The results pointed to marked heterogeneity between individual fibres in their biochemical response with exercise, independent of fibre type.

The epidemiology of lung cancer in Xuan Wei, China: current progress, issues, and research strategies

In Xuan Wei, a rural Chinese county of about one million people, females' annual lung cancer mortality is China's highest, and males' is among China's highest. Xuan Wei's very high indoor air pollution levels (sometimes exceeding 20 mg/m3), residentially stable population, relatively uncomplicated lifestyle, and wide geographic variation in lung cancer mortality render it highly amenable to quantitative, interdisciplinary investigation of chemical carcinogens due to indoor air pollution. To date, epidemiologic findings reveal a closer association of lung cancer with the indoor burning of "smoky" coal (as opposed to "smokeless" coal or wood) than with tobacco use or occupation. Current aerometric, chemical, and toxicologic findings tend to confirm this association, though the specific carcinogenic constituents of Xuan Wei indoor air pollution have not yet been determined. Chinese and American investigators are conducting interdisciplinary field and laboratory investigations to quantify the lung cancer risk attendant on indoor air pollution relative to other factors, to measure and compare the characteristics of pollution from different Xuan Wei fuels, to determine the relative etiologic importance of pollution composition and concentration, and to develop quantitative relationships between air pollution dose and lung cancer risk.

Lung cancer and indoor air pollution in Xuan Wei, China

In Xuan Wei County, Yunnan Province, lung cancer mortality is among China's highest and, especially in females, is more closely associated with indoor burning of "smoky" coal, as opposed to wood or "smokeless" coal, than with tobacco smoking. Indoor air samples were collected during the burning of all three fuels. In contrast to wood and smokeless coal emissions, smoky coal emission has high concentrations of submicron particles containing mutagenic organics, especially in aromatic and polar fractions. These studies suggested an etiologic link between domestic smoky coal burning and lung cancer in Xuan Wei.

The goodenough-harris drawing test as a measure of intellectual maturity of youths 12-17 years, United States

This report presents data obtained from a modified version of the Goodenough-Harris Drawing Test administered to a national probability sample of youths 12-17 years of age in the United States in the Health Examination Survey of 1966-70. Information presented here is essentially a continuation of that reported for children ages 6-11 in a previous publication of the Vitul and Health Statistics series. This is the first report on test findings among adolescents and is limited to consideration of age and sex differentials. The Health Examination Survey is a program of the National Center for Health Statistics in which data are collected by direct examination of representative samples of the noninstitutionalized population of the United States. Since 1960 the Survey has been carried out in a series of separate programs (called "cycles") concerned with segments of the total population and focused on certain aspects of the health of that subpopulation. The data presented here were obtained in the third cycle, a survey of the Nation% youths aged 12-17 years. This program was a continuation of the previous cycle in which children 6-11 years old were given basically the same examination and which focused on health factors related to growth and development. Details regarding the surveys can be obtained in comprehensive reports on the children's program and that of the youths. Further information regarding the Cycle III survey design can be found in appendix I.